# BMW R7 Motorcycle Engine



## gbravo (May 9, 2011)

I introduce my engine, is replica of BMW R7 Motorcycle engine in 1/4 scale.
The two cylinders boxer engine with bore 20 mm, stroke 18 mm, spark plug.


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## dsquire (May 9, 2011)

gbravo 

This looks like an interesting little engine. I will be following along as you bring it to life.  :bow:

Cheers 

Don


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## gbravo (May 9, 2011)

This is the first set of pictures
The Crankcase


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## gbravo (May 9, 2011)

More crankcase


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## Chitownmachine (May 10, 2011)

Looks great!!! Can't wait to see it come along!


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## moanaman (May 10, 2011)

Will be following this with great interest. Love boxer engines. Drive a Subaru or my wife does. didn't realize it was was as simple as it seems in design. Did you make a casting or did you mill from a billet? 

Barry G


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## metalmad (May 10, 2011)

Mate this is just brilliant, I love it ,show me more :big:
Im thinking of doing a twin for my next engine ;D
will be following along for sure
Pete


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## BillC (May 10, 2011)

This is an excellent project!! - the photo may relate why I feel that it is... My favorite ride!


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## Dave G (May 10, 2011)

Very nice engine gbravo, can't wait to hear it run. Dave


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## gbravo (May 10, 2011)

BillC,
This bike is exactly the same engine, R1000/7.


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## gbravo (May 10, 2011)

Sorry R100/7


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## halvoric (May 10, 2011)

Awesome. I want to build a scale R60/2 or R69S engine--you have beat me to it. Watching with great interest.


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## RManley (May 10, 2011)

Yey, another motorbike engine  Looking very nice so far!

Bookmarked and will follow with interest.

Rob.


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## steamer (May 10, 2011)

That's a great looking bit of machine work!  Keep it coming!

I think this was asked...is that from billet or from a casting?

Tool marks seem to indicate billet....but I could be wrong.

Dave
 :bow:


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## metalmad (May 10, 2011)

Looks like a nice big block of alli in a CNC to me 
great work 
Pete


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## Brass_Machine (May 10, 2011)

That is my question... carved from a solid chunk??

Very nice btw!

Eric


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## gbravo (May 10, 2011)

Yes, is machined from solid bar in home made CNC machine with 4 axis.


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## gbravo (May 11, 2011)

Now the timing case


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## Brass_Machine (May 11, 2011)

Wow... that is coming along very nicely. Excellent work so far!




			
				gbravo  said:
			
		

> Yes, is machined from solid bar in home made CNC machine with 4 axis.



I would like to see what your CNC is about. Would you mind sharing some pictures/info on it?

Many Thanks!

Eric


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## gbravo (May 12, 2011)

Eric,
My machine is a Grizzly Mini Mill Sieg X2, modify to CNC with the following home made main upgrades:
Reinforced colum and new balance system.
Grinding Dovetails and taper Gibs
Ball screws with back to back ballnuts leadscrews in all axis.
Stepper motors, Keling Technologies KH23H2100 with 570 oz/plg
CNC software Mach3
Control Drives Gecko-Drive
4th axis with harmonic gear and stepper motor.
All of this has been made in my home with my own design.

I will take some picture for show my workshop.
German


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## gbravo (May 12, 2011)

Crankshaft


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## gbravo (May 12, 2011)

More Crankshaft


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## metalmad (May 12, 2011)

Thats lovely mate
Pete


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## gbravo (May 13, 2011)

Connecting rod


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## Brass_Machine (May 13, 2011)

Wow! Nice work.


Sent you PM...

Eric


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## RManley (May 13, 2011)

Its only when you see a photograph that it makes you realise how small 1/4 scale can be. Are there more parts already made or are you working like a mad man 

really nice


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## gbravo (May 14, 2011)

Yes, I have almost all parts finished.
I show one part each day.
German


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## gbravo (May 14, 2011)

Now Pistons


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## RManley (May 14, 2011)

gbravo  said:
			
		

> Yes, I have almost all parts finished.
> I show one part each day.
> German



Ha what a tease. cant wait for the next installment


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## Brian Thomas (May 14, 2011)

What a great project and super skills displayed.


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## gbravo (May 15, 2011)

Today Camshaft.
This is one of main differences, in the original motor the movement of camshaft is with chain and in my engine is with gears, for this reason the cams are in opposite way.
I don't know any small chain.


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## narrowgauger (May 15, 2011)

gbravo

I am in awe of your BMW engine. will be looing forward to the next episode.

noticed that you were looking for small roller chain. Perhaps this may help:

- 0.1475 inch pitch roller chain (3.75mm pitch) is available from Precision Scale Model Engineering [[email protected]]
- material stainless steel.
- sprockets available, although I normally cut my own.

Larry DeMilo is a great guy and will be happy to help if you need smaller pitch roller chain.

have fun
Bernard


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## gbravo (May 15, 2011)

Very interesting information.
I will consider in future proyects.


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## gbravo (May 15, 2011)

In my impresion the rockers was the most interesting parts made.
The black color is due to annealing.


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## gbravo (May 15, 2011)

More Rockers


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## BillC (May 16, 2011)

Now, you're going to need to expose how you made those rockers....They're pretty darned accurate and nicely shaped - beautiful.

BillC


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## gbravo (May 16, 2011)

I dont have pictures of the machining, but I will try to explain how I made rockers.
1. First I turn a stock cylinder of SAE 1045 steel to diameter 19 mm and long 38 mm.

2. Turn one of ends to dia. 17 mm with 24.5 mm long, this diameter is the center cylinder of the rocker with length increased in 20 mm for clamping.
(See rocker1 picture)

3. I place the stock in the CNC mill and I milling in Z axis (0 degrees) with horizontal milling in 3 axes
(See rocker2 picture)

4. Rotate in 90 degrees and mill
(See rocker3 picture)

5. Rotate to 180 degrees and mill
(See rocker4 picture)


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## gbravo (May 16, 2011)

6. Rotate to 270 degrees and mill
(See rocker5 picture)

7. I milling finishing in 4 axis with continuous rotation in axis A (around X axis)
(See rocker6 picture)

8. Finally I turn the inside hole (4 mm) and cut the center cylinder of the rocker to the finish length.


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## gbravo (May 16, 2011)

Cylinders


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## Brass_Machine (May 16, 2011)

errr... wow! those rockers are pretty cool!


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## gbravo (May 16, 2011)

More cylinders


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## cfellows (May 17, 2011)

Very nice project. Beautiful work and an interesting engine to model. Thanks for taking us along on the ride.

Chuck


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## gbravo (May 17, 2011)

Now another interesting part
The cylinder head ...


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## gbravo (May 17, 2011)

down side


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## mu38&Bg# (May 18, 2011)

Very nice! Which CAM software are you using?


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## ToniTD1490 (May 18, 2011)

German your are making a wonderful work! I would like seeing some pics of your CNC mill. I am jealous. ¡Bien hecho!.

ToniTD1490


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## gbravo (May 18, 2011)

This parts are made using VisualMill Cad software

My CNC mill is in Machine modifications

http://www.homemodelenginemachinist.com/index.php?topic=14490.msg149034


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## gbravo (May 26, 2011)

After some very intensive days of off road travel, with 2200 km. around the Uyuni Salar, who is the biggest salt flat in the world, located in Bolivia. This salt flat has 12.000 Km2, 160 km. length and 3650 meters of altitude.


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## gbravo (May 26, 2011)

Now I will continue with my engine show.
Cylinder and head together


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## dsquire (May 26, 2011)

gbravo  said:
			
		

> After some very intensive days of off road travel, with 2200 km. around the Uyuni Salar, who is the biggest salt flat in the world, located in Bolivia. This salt flat has 12.000 Km2, 160 km. length and 3650 meters of altitude.



This looks very interesting. Please tell us more about your adventures on the salt flat. I am sure many MadModder's would be interested to learn more.

I love the work that you are doing on the engine. :bow:

Cheers 

Don


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## gbravo (May 27, 2011)

I am very enthusiastic in off road trips and fortunately in my country we have many places for motorbike travels in dessert, mountains or very green places. 

This trip began in dessert in the north of Chile, then we up to the high plain in Bolivia, where the Andes are widest and extensive with a high plateau over 3500 meters, in some places exceed 4000 meters. In this condition with low temperatures deficit of oxygen you need to be very careful because any effort is very heavy.

After ride over bad roads with strong winds and sand wind, you arrive in the sunset to very comfortable hotel in the border of the salt flat. This Hotel is built completely in salt, inclusively the beds and sits are made in salt with comfortable cushions over it.

The Uyuni salar is very intensive and beautiful with low temperatures, high altitudes and in this opportunity the salt flat was covered in big extensions with about 50 mm (2 inches) of water, besides his impressive extension where you dont see his limits.


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## gbravo (May 27, 2011)

Now more engine parts.
Today, the front cover


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## dsquire (May 27, 2011)

gbravo

Thank you so much for telling us about your ride and the pictures of the hotel made from salt. That is the beauty of these forums, you get to learn about other peoples lives and pastimes as well as learn about their country. I would imagine that upon arriving back home a good wash down to remove salt would be one of the first priorities.  :bow: :bow:

Cheers 

Don


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## gbravo (May 27, 2011)

Really, we wash the bikes when exit the salt flat, before return to dirt road.
In this picture you can see the engine before wash.
German


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## kustomkb (May 27, 2011)

Beautiful work gbravo!!


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## gbravo (May 28, 2011)

The Upper engine cover


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## gbravo (May 28, 2011)

Rocker box cover


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## gbravo (May 28, 2011)

More


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## stevehuckss396 (May 29, 2011)

Bravo! Gbravo

I have been following along from the beginning. Great work. Will be following til the end.


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## gbravo (May 29, 2011)

Today I show the exhaust ...


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## gbravo (May 29, 2011)

and the exhaust nut


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## nfk (May 30, 2011)

Hi,
German, you`r making an exceptional work!
All those parts are reproduced with an incredible detail level! :bow:
Congratulations!

I went at the salt flats last January myself, following the rally Dakar and i must admit, i envy you so much for being able to ride in that incredible place!

Cheers,
Norberto


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## gbravo (May 30, 2011)

Norberto,
Is a great fortune to have the Dakar rally in south america.
I have followed the rally for three years.
German


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## coopertje (May 30, 2011)

Hi German,

Wonderfull work :bow: :bow: :bow:

Do you ever sleep? You are making parts so fast, incredible. Love the details and finishing.

Thanks for sharing!

Best regards Jeroen


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## gbravo (May 30, 2011)

I work, sleep and repose,
most parts showed was finished when I start this show.

German


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## gbravo (May 31, 2011)

Carburetors


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## agmachado (May 31, 2011)

Hi German,

Congratulations... the look is absolutely great !!!

Thank you for share with us...

Take care,

Alexandre


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## gbravo (Jun 1, 2011)

Now some external parts


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## Xlmyford (Jun 1, 2011)

gbravo  said:
			
		

> Carburetors



Hi,this is no miniature constant velocity BING carburetor.
You can´t cheat that way! 

I´m just joking.
Incredible work,my deep respect.
Cheers,Ralph


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## gbravo (Jun 1, 2011)

Really,
If you check in the previous posts, this is the only without comparison with the original.


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## krv3000 (Jun 2, 2011)

HI brill work :bow:


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## gbravo (Jun 3, 2011)

After 2 years of working, I finished the engine parts and start the assembly


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## gbritnell (Jun 3, 2011)

An outstanding piece of machining. Now comes the fun part, running and fine tuning.
gbritnell


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## dsquire (Jun 3, 2011)

German

Seeing all those parts laid out like that is certainly impressive. It is easy to see that a lot of time has been spent machining the individual parts to make the complete engine. I will be watching closely as you assemble this engine and turn it into a running engine. Thanks for allowing us to watch over your shoulder.

Cheers 

Don


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## ozzie46 (Jun 3, 2011)

*" FANTASTIC"* This is going to look great. :bow: :bow: :bow: :bow:

 Ron


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## gbravo (Jun 5, 2011)

Help ... ??? ??? ??? ???
I am having problems for upload more pictures, it show me the following
error:
"The attachments upload directory is not writable. Your attachment or avatar cannot be saved. "
I dont know why.

Regards,
German


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## gbravo (Jun 17, 2011)

Finally the update pictures problem was repaired. 
Now we can start assembling the engine.
The first stage is to assemble the crankcase with cranksaft, bearings and camshaft.


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## gbravo (Jun 17, 2011)

Continuing with timing case


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## gbritnell (Jun 17, 2011)

Elegant piece of work there gbravo. Having worked on a few of these (points models) I was wondering how you're going to set up your ignition?
gbritnell


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## gbravo (Jun 19, 2011)

I am testing different configurations because I have irregular sparks


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## gbravo (Jun 19, 2011)

Continuing with assembling I show the cylinders and head


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## RManley (Jun 20, 2011)

Absolutely stunning work. Its models like this that make me want to stop uni and just spend all my time in the workshop. Are you considering making the whole motorcycle or just the engine??

 Rob.


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## gbravo (Jun 21, 2011)

Rob,
I am considering making only the engine.
As I finishing this proyect, I am working in design and develop the following engine, it will be the Wright J5.
But I am thinking in a real Wrigt J5, not the design published in SIC, that have only the name of Wright J5.


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## gbravo (Jun 21, 2011)

More assembly


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## gbravo (Jun 21, 2011)

Continuing the assembly ...


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## ShedBoy (Jun 21, 2011)

That looks ready to go nearly, amazing looking engine :bow: looking forward to the video.

Brock


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## gbritnell (Jun 21, 2011)

gbravo, 
Excellent as ever. I see what is probably a vent on top of your crankcase. One of the issues I ran into with my V-twin was the pressure pulses in the crankcase. I had built a stubby vertical vent for mine which worked fine at slower rpm's but when I revved it up it would push oil out. I kept increasing the height of the breather until now I only get a trace of oil coming from it. 
gbritnell


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## gbravo (Jun 21, 2011)

The boxer twin engine is the most critical configuration in terms of crankcase internal pressure, beacause both cylinders go forward and backward together.
For this problem the more common solution is a vent valve for maintain negative pressure in crankcase.
If you see the first picture with the original motor in this thread, you can see the vent valve on top of the crankcase.  
German


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## gbravo (Jun 21, 2011)

If you compare the pictures 5 and 4 places before this post, named "Vent and cylinders" and "Hall sensor and exhaust pipes", you can see the magnet flywheel in the first picture made in aluminum and plastic material in the other. This change is due to recommendation of Roy Sholl fron CNC-engines about his CDI systems

This is copy of Roy information:
"One more thing. We have been working on hall sensor failure issues. These are very erratic and not too common just a pain in the tush. The one thing we've found is mounting the magnet/magnets in Delrin or other non electrically conductive material is best. For set ups already done we have found that gluing a .020-.025 plastic shim ( I use the fake credit cards that come in the mail ) onto the face of the hall sensor or if possible making a disk at least the same diameter as you magnet rotor will also eliminate the possibility of a sensor failure. If you glue a piece of plastic onto the face of the sensor it should be approximately 25% larger on all sides as the sensor body and I usually make it long enough to cover the leads also."

Regards,
German


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## gbravo (Jun 21, 2011)

This picture is the first complete engine assembly and I begin with the start engine intents.
After many intents, I observe that the engine is lack of compression. 
I made an adapter for apply compress air and determine where the leakage is, I concluded that the problem was in the valves.

Removing the cylinders head, grinding the valves with number 600 compound and made one new valve, I assembly newly, but the engine decline start. I was many hours trying to start the engine without success.

Reading in some web pages and forums, I read that the cylinder liner finishing recommended is mirror finish and my finish was with cross hatch pattern, then I decided to build new liners with mirror finish and with some minor diameter for readjust the tolerances with pistons. But the motor continues declining to start with the new liners and pistons and rings well adjusted (in my point of view). The engine continues with lack of compression


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## metalmad (Jun 22, 2011)

Keep after it German
your so close now 
Pete


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## gbritnell (Jun 22, 2011)

Hi German,
 When getting to this point in engine building it is very frustrating to know that you have done good work but can't get the engine to work. 
 From what you say you have tried to fix or fixed the problem areas, although having a mirror finish on the cylinder liners is not what I would recommend. They need a slight scratch pattern to hold oil and seat the rings in. 
 It's strange that both cylinders have no compression. If you remove the heads and put the heel of your hand onto the cylinder and turn the engine over does it feel like it has vacuum on the downstroke and compression on the upstroke? If so then it should have enough compression to start the engine. I'm assuming that when you reground the valves they are in fact sealing. 
 With these elements proven out maybe you should look at something else. Are your cams timed correctly? It's possible that a small error in cam timing can prevent the engine from building enough compression to start. 
 With the quality of your build I would think that this wouldn't be an issue but from what you say I don't have any other place to look. 
gbritnell


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## Lakc (Jun 22, 2011)

Sorry to hear about your troubles, its very excellent work so far. 
Take a close look at your camshaft, and compare it to the factory one in the picture you posted. Looks like the factory cam is IIEE and you made your IEIE.


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## Admiral_dk (Jun 22, 2011)

Your first finish with at cross hatch inside the cylinders are the correct way to do it, alternatively start with a mirror finish and use a hone to make the correct cross hatch pattern is even better when we're talking about an IC engine.

As stated, those "lines" are holding a small amount of oil in them + decreasing the friction ( a mirror finish gives the highest friction possible) and helps with bedding the rings.

It sounds like you're running into the same problems as most builders of small four stroke engines - getting the valves to seal correctly. Remember that the seat (the grey area you'll see on the valve and seat in the head) should be a tiny unbroken ring a few tenths of a millimeter in with on all the valves and seats.


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## gbravo (Jun 22, 2011)

Lakc  said:
			
		

> Sorry to hear about your troubles, its very excellent work so far.
> Take a close look at your camshaft, and compare it to the factory one in the picture you posted. Looks like the factory cam is IIEE and you made your IEIE.



What is IIEE and IEIE?


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## mu38&Bg# (Jun 22, 2011)

Cams look fine in the 3D model on the first page.

Edit:----------------------
Actually, I'm not sure. Something seems strange in the model, and I'm not sure which side is exhaust.


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## ozzie46 (Jun 22, 2011)

I= intake, E= exhaust. So IIEE = intake intake exhaust exhaust and IEIE= intake exhaust intake exhaust.


 Absolutely beautiful work by the way. :bow: :bow: :bow: :bow:

 Keep after it you'll get running.

 Ron


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## Lakc (Jun 22, 2011)

Or it could be EEII but Ron is correct, I meant intake and exhaust lobes. It looks like you swapped the center two lobes in the picture of your production one versus the picture of the factory one.


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## gbravo (Jun 22, 2011)

Right, in my engine is EIEI, starting with left cylinder and the original is EEII.
German


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## willburrrr2003 (Jun 22, 2011)

I have to say your engine is simply stunning!! I can see the care put into building it, and can't wait to see it running!! 

Regards,

    Will R.  Everett, WA


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## gbravo (Jun 23, 2011)

Sorry guys,
In this moment, the compression problem has been solved.

Continuing with my history, after the troubles with new liners, I recheck the compression with compress air, with that I can see that the cylinders continue leaking to the crankcase, not from valves.

As I have reading many posts about the difficult in to make good rings, I assumed the problem was in the rings, and make new rings, after assembly the engine as the problem continue, then I make more rings.

As the problem continued and the previous rings was made with Chaddok/Walshaw method, I decided change to the Trimble method and make more rings, but the compression not Up, even turning the engine with drill for obtain more adjustment between rings and cylinders, continues leaking.

At this point, the only part that I not have made new was the pistons, well, I make new pistons. With those new pistons, oh surprise, the compression raises magically with minimum leakage. But, what was the problem?

Investigating in the web I concluded that the problem was in the groves rings. When I made the groves I turn the grove with a tool more narrow respect to the grove and then I adjust the grove width with the same tool. With this method and so thin tool, the grove walls are not straight, they are some tapered and the seal between piston and ring is not right. In the new pistons the groves was turning with tool with the same grove width and with only one tool pass.

After those changes, I could hear by first time some explosions in the exhaust pipes.
Now, the engine should be start, but I discovered an ignition problem. Because I connected the CDI to one coil and then to both sparkplugs in parallel, with this configuration, I could start the engine with only one cylinder running and the other with the sparkplug removed. At this moment, at least the engine start with one cylinder but start 

Investigating this new problem, some persons tell me that this configuration with both sparkplugs in parallel and with waste spark, not work because the difference of conductivity in both compress chambers, weak the spark in the compressed chamber.

Then the solution is to buy another coil and connect each sparkplug with corresponding coil.  

In the following picture you can see the old cylinder liners a lot ot rings for different liners and with different methods.and pistons


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## Rayanth (Jun 23, 2011)

I am glad to hear you solved your compression problem! It's interesting how it often turns out to be something we never even thought of, and we were so SURE we knew what the problem was...

I am not sure if you would need a separate coil for each cylinder, that doesn't sound right for some reason to me, but i'm not the expert on ignitions... I am certain someon will be along to help you soon on that 

- Ryan


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## gbravo (Jun 23, 2011)

Ryan,
In this topic you can see the discussion about two coils,

http://www.homemodelenginemachinist.com/index.php?topic=14434.msg148516#msg148516


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## Rayanth (Jun 23, 2011)

just knew I'd be proven wrong, thanks


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## Admiral_dk (Jun 23, 2011)

You're in trouble with two plug in parallel .... Just as you discovered :

When you do it that way, you have a fast rising voltage when the system fires. At some point in time this voltage will be high enough for one (or the other) plug to create a ionizing path resulting in a spark. At this point, the plug goes from being a very high impedance (AC resistance) to a very low impedance. This reduces the voltage from the coil from several thousands to a few hundred volts and this effectively prevents the other plug from firing.
Since the voltage where the ionizing occurs need a higher voltage, the higher the pressure in cylinder is - you're effectively only firing the "waste" plug and never the one that needs to be fired - the one with a compressed gas :-\

That's why I suggested that you connected one end of the coil to one plug and the other end to the other plug - this is the way ALL four cylinder Japanese motorcycles worked before electronic ignition ...!
It might give you a lot of EMI problems - but if this is a stationary display model, it might not give you any problems - If it weren't for the fact that you use a Hall sensor as the trigger.

Looking forward to see a video of it running - You've done a work of art so far :bow:

Best wishes

Per


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## Lakc (Jun 23, 2011)

In order to use the single coil, you need a somewhat special kind without a grounded secondary. Many automobiles use these, often found in banks of two or three coils for waste spark. Each end of the secondary has its own coil terminal to run to a spark plug.


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## gbritnell (Jun 23, 2011)

When I built my V-twin engine I was lucky enough to have a coil with 2 high tension leads coming out of it. I had purchased it from Jerry Howell many years ago and wondered if I'd ever have a use for it. They discontinued making them a couple of years back. Shame! I don't know what I'll do if it burns out. I watching to see what kind of answers you get.
gbritnell


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## RonC9876 (Jun 23, 2011)

Guys: The single spark ignition system as sold by Roy Scholl can be wired to produce two sparks at once as used on a waste spark twin. I am using it to fire both plugs at once for my Hercules engine. The coil on this system usually has one end grounded to the engine block. You simply remove this ground wire and connect it to the second plug. This coil is double ended and isolated from ground in this configuration. Both plugs are now in series and they both HAVE to fire together. This set up really works well. Just remember to do away with the ground wire all together. Ron Colonna                       P.S. Ask Roy about it if you think I'm wrong. He had been selling a dual spark system with two coils but I think it was Doug Kelly that told him about this way to wire his single spark coil to produce dual sparks at the same time.


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## gbravo (Jun 23, 2011)

Ron,
When you used this system, your sensor was hall or mechanical contacts?

I asked Roy about this connection and his response was:

"I have recently had two modelers successfully use one of our single spark CDI systems on twin cylinder waste spark engines. What I did was leave the ground wire off from the secondary back to the ground on the board. They used 2 spark plug wires, 1 on each of the spark coil terminals ( this does not use a ground wire ) to each of the spark plugs. The ground path is through the engine from one spark plug to the other. In both cases this worked very well on their engines."

My only doubt about this connection is what happend with the hall sensor, while the sensor has a separate ground connection, it is glued to the crankcase, where have a high voltage and the hall signal wires are very thin not designed to work with high voltages, then could have an electric shock that burn this sensor, due to those wires are near to this high voltage surface.
Am I right or my doubt is exaggerated?

Regards,
German


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## nfk (Jun 23, 2011)

Hi,
Why not use an original BMW coil? 

Or maybe use any other wasted spark coil, my old kawasaki z650 has 2 double output coils in a wasted spark configuration and those where kept in use after upgrading to CDI ignition.
The link below ir for a couple of old Honda CB coils, if those fit an old CB600 then one of those should work for your engine/CDI.
http://articulo.mercadolibre.cl/MLC-34976742-bobinas-honda-cb-_JM

Another option could be to wire the sparks in "series".
Wire the live end of the coil to one of the plug and wire the ground terminal to the other coil.
Beware that way there is no ground reference on the engine and if your CDI is using any part of the engine for ground reference it wont work. (and you could burn the CDI)

Cheers,
Norberto


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## gbravo (Jun 23, 2011)

Because my plan is locate the coils below the upper engine cover as you can see in the picture showed in reply 89.
The coils from CNC-engines go in this place, even two coils.


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## Lakc (Jun 23, 2011)

gbravo  said:
			
		

> My only doubt about this connection is what happend with the hall sensor, while the sensor has a separate ground connection, it is glued to the crankcase, where have a high voltage and the hall signal wires are very thin not designed to work with high voltages, then could have an electric shock that burn this sensor, due to those wires are near to this high voltage surface.
> Am I right or my doubt is exaggerated?


German,
High voltage electricity can behave in funny ways, but if you understand whats happening you can take the proper precautions. Hall sensors are notorious for failing on these type of ignitions, and you are right to be careful, but understanding electricity in this case will show you how to be safe. 

 Your engine is probably ground potential, 0 volts, to the battery and ignition system. The ignition transformer turns the battery voltage to 300-500 volts and flows across the ignition coil primary windings. This sets up a magnetic field with the current flow that collapses when the ignition controller wants a spark. That magnetic field moving across the secondary coil creates a new voltage, say 20,000 volts, which is enough to jump the gap in the spark plug gap. This 20,000 volts is _only between the two ends of the coil secondary_, if you could measure the voltage to the coil primary or ground, it would be 0. Now when you take one end of the coil wire and go to the cyl 1 plug, and the other end to cyl 2 plug, your spark jumps from plug 1 ----shell>-->block--->shell of plug 2--->plug 2 electrode---> back to the coil secondary. 
Although the block is part of the path of the voltage, as long as the hall sensor is not near either plug electrode, it should be at 0 volts to the secondary 20,000 volts.
There are many variables that determine if you can blow a hall sensor, usually from the ignition board itself, or allowing the hall wiring too near the spark plug wires or coil wires, but you shouldnt blow the hall from a waste spark system like I just described.


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## RonC9876 (Jun 24, 2011)

Guys: My Hercules uses a Hall sensor to trigger the system. It is well isolated from any high voltages and I haven't had any problem with any burnouts. In fact I have never had a Hall sensor fail on any of my myriad of engines that use them. I take that back. One did fail due to vibration when one of the leads to it broke off. No problems due to high voltage spikes though. Best of luck. By the way the two modelers Roy spoke of were me and Doug Kelly. Ron Colonna


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## gbravo (Jun 28, 2011)

Finally my engine starts,

[ame]http://www.youtube.com/watch?v=K7UzI7dA8wc[/ame]

In this video, the engine is running with his two cilinders and two coils located below the engine.
German


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## willburrrr2003 (Jun 28, 2011)

WOW :bow: :bow: you did a hell of a job, It looks fantastic and sounds great too!!!

Regards,

  Will R.


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## steamer (Jun 28, 2011)

Outstanding job German! Well Done!

Dave

 :bow: :bow: :bow:


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## ozzie46 (Jun 28, 2011)

Way to go! I knew you would get it. :bow: :bow:
 Love the sound.

 Ron


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## RManley (Jun 28, 2011)

Very very nice and sounds great too! Those rockers are too nice to cover up ;D

Are you going to try the waste spark method? interested because thats probably what im going to do.  

There cant be much left to do to finish it now (except a motorcycle to put it in  ) 

I would love to see some models from this forum in person, shame I cant afford a round the world ticket!

Rob.


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## coopertje (Jun 28, 2011)

Congratulations with this beautiful engine, its a true state of (modelling) art :bow: :bow: :bow:

I hope to see this engine soon on top if this site as project of the month, it does not deserve less!

Regards Jeroen


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## nfk (Jun 28, 2011)

Very nice engine!
Congratulations! :bow:


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## dsquire (Jun 28, 2011)

German

This is a beautiful engine that you have so carefully constructed. I am sure that it will be a good runner for you when you have it broken in and fine tuned. Thanks for providing the many photos of your progress as you built this fine engine. It was my pleasure to watch this engine come to life. :bow: :bow:

Cheers *beer*

Don


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## Lakc (Jun 28, 2011)

Good going! :bow:


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## gbravo (Jun 29, 2011)

Thank for your inspirit mails, now I am seeing the exit of tunnel.
In this moment (when I have free time) I am working in repair some few oil leakage in the timing case, adjusting the external covers, finding the best ignition configuration for locate the coils in his place (under the upper engine cover) and obviously tuning the engine.
German


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## Groomengineering (Jun 29, 2011)

Very nice work German!  Thm:

Cheers

Jeff


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## dgjessing (Jun 29, 2011)

It's a beauty! I can only hope to someday do an IC engine (let alone such a nice one) .


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## gbravo (Jun 29, 2011)

You only need propose you and work with enthusiasm and lot of patience.
This is my first engine and I am so satisfied with this proyect, that I am working in design my next engine.


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## gbravo (Jul 3, 2011)

When I built the engine for the first time I connected the two spark plugs in parallel with a single coil and as I explained in some previous messages, this system does not work due to the difference in conductivity within compressed combustion chamber and the chamber with lost spark. Then when I got a second coil, I fabricated a new bracket to place both coils at the top of the engine, trying to start the engine with this configuration I was not successful and noticed that the spark plugs had both a lower intensity, so remove coils from that position and put them out of the engine, starting immediately the engine, as seen in the video shown last week. 

Now, I try to reassemble the two coils over the engine but be noticed that with the two coils together, exist interference between the magnetic fields, affecting the intensity of the spark. To try to solve this problem, both coils was rotated 90 degrees in order to place both in parallel but had no success, even tried to place a non-magnetic metal plate between the two coils, increasing the electrical isolate in both coils, etc, but none worked. 

Finally, although I had some fear of the electrical insulation, I connected a coil over the engine with the plugs in serial, finally achieving an excellent result with the engine running very well with the coil in his place. For this connection, I increase the isolation in all wires from the hall sensor and the primary coil.

I've done several tests with this configuration with very good results, even I have reviewed the effect of electrical noise generated by this configuration, without noticing any interference. I have therefore decided to keep this setting.

German


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## gbritnell (Jul 4, 2011)

Hi German,
It looks like a nice compact installation. So to go over what you are using. It's an S&S ignition with the coil and circuit board separated. The coil is then tapped off of the other ground connection for the second plug. Your Hall wires go to the circuit board which you have mounted remotely. Is that about right?
gbritnell


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## gbravo (Jul 4, 2011)

George,
Yes, is an S&S CDI with separate coil (actually, originally had the coil attached, but I removed it and cut the diagonal ground link, anyway are equal).

 The coil was rotated by 90 degrees from the first position so that the primary terminals are at the rear and secondary terminals to the front.

From the CDI card three wires go to the Hall sensor and two wires to the coil. For the wires to the hall sensor I used an old mouse wire, in which I removed the outer cover, leaving the screen to view. This cable, together with a common two leads wire, was introduced in a heat shrink tubing in order to form a single electrical cord with the hall sensor signal electrically isolated from the signal to the coil. This is the wire that you see in the lower right corner of the last photo. Arriving at the rear of the coil, both wires to the primary leave the cord and the shielded continue inside heat shrink tubing to the right side of the coil and connect to the Hall sensor with Futaba connector.

From the secondary each terminal is connected directly to each spark plug.

I also like this solution because it is very clean and compact.

Regards,
German


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## Admiral_dk (Jul 4, 2011)

Your final solution is VERY similar to a full size bike of yesterday and the R7 model range are from yesterday (my youth) - I love it !

I'm very impressed and even more by the fact that this is your first :bow:


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## Lakc (Jul 4, 2011)

gbravo  said:
			
		

> Finally, although I had some fear of the electrical insulation, I connected a coil over the engine with the plugs in serial, finally achieving an excellent result with the engine running very well with the coil in his place. For this connection, I increase the isolation in all wires from the hall sensor and the primary coil.



Thats the way to do it! Those systems are hard on hall sensors anyway, so there is no guarantee they will last forever, but as long as the plug wires dont fall off or ground out any failure wont be because of the serial plug connection.


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## gbravo (Jul 4, 2011)

I covered all wires with Nomex (special insulator paper used in high tension transformers and electrical engines) and over this I apply heat shrink tubing.


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## Lakc (Jul 4, 2011)

Thats fine, its about all you can do. I think some of the hall sensor failures occur at board level, not necessarily the wiring. From what I can tell, the commercial and diy designs seem to lack a bunch of components that contribute to circuit "robustness".


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## gbravo (Jul 4, 2011)

OK, I will cross my fingers


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## gbravo (Jul 18, 2011)

Gentelmans,
Finally my engine is finish,

This is the original BMW R100 with R7 engine





and my engine,





From upper left side,









And front view









German


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## gbravo (Jul 18, 2011)

More pictures,























































German


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## gbravo (Jul 18, 2011)

And the engine running ....

[ame]http://www.youtube.com/watch?v=2ByWEupWAZU[/ame]


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## ShedBoy (Jul 18, 2011)

Great runner well done :bow: :bow:
Brock


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## metalmad (Jul 18, 2011)

That is just gorgeous!!
Pete


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## steamer (Jul 18, 2011)

metalmad  said:
			
		

> That is just gorgeous!!
> Pete



Isn't it!  :bow: :bow:

Dave


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## gbritnell (Jul 18, 2011)

Congratulations on a superb build. This is the type of work I enjoy doing and really appreciate it when others do it. Now that you have this finished what is your next project?
gbritnell


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## dgjessing (Jul 18, 2011)

Fantastic! Now how about the rest of the bike? ;D


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## gbravo (Jul 18, 2011)

gbritnell  said:
			
		

> Now that you have this finished what is your next project?



Now I am finishing the design of my next proyect, It will be replica of the Wright J5.

German


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## kustomkb (Jul 18, 2011)

Outstanding!

Beautiful work, I look forward to following the Wright build.


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## gbravo (Jul 18, 2011)

I will make a new video with another camera because the sound is not good.


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## mu38&Bg# (Jul 18, 2011)

The engine is excellent!

Regarding the sound in the video. I notice many videos here have noise on video recordings due to unshielded spark ignition leads. I'm not sure if some cameras are better than others at rejecting this noise, but the camera is usually close to the engine in any case.


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## gbravo (Jul 18, 2011)

dieselpilot  said:
			
		

> Regarding the sound in the video. I notice many videos here have noise on video recordings due to unshielded spark ignition leads. I'm not sure if some cameras are better than others at rejecting this noise, but the camera is usually close to the engine in any case.



Is very possible,because this engine have both spark plugs in serial and all engine make noise.


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## Lakc (Jul 18, 2011)

EMI/RFI rejection is another problem with the commercial ignition systems, especially CDI with onboard voltage converters. 
With it running, grab a handheld AM radio and tune through the dial to see if you can hear the ignition system working.


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## gbravo (Jul 18, 2011)

As this is a stationary engine, and made to more similar possible to the original, this noise is an assume issue.
The ignition coil is locate as the original position (upper the engine) and the spark plugs wires cross the upper case at front . For minimize this noise, the coils would be outside the engine and place more wires leaving the engine, dirtying the general appearance.

If you compare those pictures with previous, you can see that I removed and arranged many wires and hoses.


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## agmachado (Jul 18, 2011)

Very cool... congratulations!!!

Cheers,

Alexandre


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## kcmillin (Jul 18, 2011)

Truly and Awesome Job! :bow:

Well Done

Kel


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## IronKid (Oct 10, 2012)

man, my respects!!!


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## Herbiev (Oct 10, 2012)

I too would like to know if you made the castings or machined from stock


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## Charly82 (Jun 29, 2013)

Hello.  First of all, awesome job, it looks and sounds fantastic.
The reason why I joined, is to get in touch with you to see if it's possible for you to send me the blueprints of this engine.  I'm trying to make a 3d model of it and I haven't been able to find anything acurate so far.
If it's not possible I'll understand, I know this is something you've put a lot of time in to, and some people won't just give it away.
Thank you for your time.


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## vmo (May 26, 2014)

Planes for download, please?
(In Solidworks format helps).
Good job. Congratiualtions.


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## Peter M (Jun 13, 2018)

Amazing job!!! What about rebuilding the R7 itself? 






gbravo said:


> More pictures,
> 
> 
> 
> ...


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## kuhncw (Jun 13, 2018)

German,

You've done very nice work on a challenging project.

I'm also interested in some photos of your CNC mill and shop.

Chuck


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## kuhncw (Jun 13, 2018)

Oh, sorry.  I didn't realize I'd posted in a thread from several years ago.  
I'll go back and read through the thread.

Chuck


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## e.picler (Jun 14, 2018)

Congratulations Gbravo!
Very nice/amazing  work. I will be following with great interest. What CAM are you using?

Edi


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## AdvenJack (Jun 15, 2018)

Extraordinary!!! Outright Extraordinary!!! Many congratulations to you!!!


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## Cymro77 (Jun 16, 2018)

Why am I getting all of this outdated stuff?  I see why one other fellow thought he was watching a current build or for sale item,  only to be told it was a posting from years earlier!!  Where are our up to date postings???"  I do NOT like this new website.  I am also tired of all the advertising I get thrown at me when I open the site.  At least bring the Daily Activity Report I get in my e-mail up to date!!!


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## Cogsy (Jun 16, 2018)

Cymro77 said:


> Why am I getting all of this outdated stuff?  I see why one other fellow thought he was watching a current build or for sale item,  only to be told it was a posting from years earlier!!  Where are our up to date postings???"  I do NOT like this new website.


This thread is from a very long time ago. It is only active again because a brand new member, likely brought here from a google search, joined up just to post on the thread. To be fair to him, he likely didn't realise the thread was years old. However, once the thread was reactivated, each new post showed up in the 'new posts' menu and people didn't realise it was an old thread. While we might not get any more new info on this model, the info that is there is still good to read...


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## Sabud (Jun 16, 2018)

Hello,

I am new to this forum  Got the thread from HMEM and liked it a lot. In 1967 I owned a similar BMW, a 1960 R69S with sidecar-racing tuned engine.


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## Peter M (Jun 18, 2018)

I have one too 







Sabud said:


> Hello,
> 
> I am new to this forum  Got the thread from HMEM and liked it a lot. In 1967 I owned a similar BMW, a 1960 R69S with sidecar-racing tuned engine.


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## Peter M (Jun 18, 2018)

im sorry - I didn't mean to cause trouble 




Cymro77 said:


> Why am I getting all of this outdated stuff?  I see why one other fellow thought he was watching a current build or for sale item,  only to be told it was a posting from years earlier!!  Where are our up to date postings???"  I do NOT like this new website.  I am also tired of all the advertising I get thrown at me when I open the site.  At least bring the Daily Activity Report I get in my e-mail up to date!!!


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## Peter M (Jun 18, 2018)

ok well actually I did some research since I got you guys into this Old threads and I found this sketch that seems pretty recent to me


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## Cogsy (Jun 18, 2018)

Peter M said:


> im sorry - I didn't mean to cause trouble


No worries Peter - this thread was finished before I even joined the site so I've never seen it before and it was an interesting and informative read, which is why we're all here after all...


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## Peter M (Jun 19, 2018)

Thank you for staying positive! Plus as you can see I found some new info on it. There s a company that is planning on launching massive production of this bike...at least it seems like it


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## bazmak (Jun 19, 2018)

I too found the post interesting and even though i did not know it was old i will still follow it
Sometimes ressurecting old threads is good for newcomers that may have missed it


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## Daniel McDowel (Jul 6, 2018)

Awesome! I was dreaming to have at least a replica of the 1934 BMW inspired Motor.


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## BillC (Jul 6, 2018)

Old? What's 'old' have to do with it....? We all like new and trendy stuff but when we get serious about it, we love the 'old stuff' just as much if not more.

I have the bike with this engine -R100/7 - on post #8. I build miniature engines as a hobby but it never occurred to me to take my bike apart to duplicate the engine....that is a very serious modeler to say the least. And what a beautiful job! gbravo is bravo!

BTW: I use Artsoft Mach3 operating system on a converted Enco 8x36 knee mill that is programmed using KeyCreator CAD/CAM.

BillC


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## Peter M (Jul 16, 2018)

Daniel McDowel said:


> Awesome! I was dreaming to have at least a replica of the 1934 BMW inspired Motor.


if its for real how much would you pay for it?


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