# Parksy's single cylinder four stroke



## Parksy (Apr 3, 2016)

Gday all

I have started a new project and would like to document it here for future reference and others to see.
I want to build a single cylinder air cooled four stroke engine which I could one day convert to hit and miss.
I don't have any plans so will be working with my own thoughts and copy a few things I've seen.
First thing made is the crankshaft. After having a crank that was made in sections fail I decided to try and make a one piece crankshaft. This wasn't as difficult as I thought and I'm happy with how it turned out. Made from 4140 rod.
The shafts and throw are 10mm in diameter with a 28mm stroke. Haven't decided on bore size yet, this will depend on material availability. The crank will run in ball bearings.







That's it for now. Next will be a base to mount it and the cylinder. Plan to make the cylinder out of cast iron then nickel plate it for corrosion protection. 

Cheers


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## Herbiev (Apr 3, 2016)

Are you planning on doing your own nickel plating ?


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## Parksy (Apr 3, 2016)

Yes. I have made my own nickel acetate using vinegar, nickel and a 12v power source and have plated a number of things with good success. My previous project (v8 nitro engine) I've plated the rocker arms and cylinder liners.


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## gbritnell (Apr 3, 2016)

That's a really nice looking crankshaft! I'm glad the 4140 worked out for you.
gbritnell


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## Parksy (Apr 8, 2016)

Thanks George. 

Made the cylinder this arvo out of cast iron. 50mm outer diameter, 26mm bore. Was able to achieve nice even fins. The new DRO that I fitted to the lathe is just wonderful. Was getting sick of counting the hand control rotations. Bore looks good too. Will mount the cylinder on the mill and drill the required mounting holes, then nickel plate it. I want to avoid plating the bore, does anyone have any suggestions on how I could do this?







Cheers

Andy


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## Parksy (Apr 15, 2016)

Working on the housing at the moment. Machined from a solid block of 6061. Chosen to use large bearings to support the crankshaft. One thing that is apparent is that I may not have made the crankshaft long enough to add the hit and miss components at a later stage. I will have to work something out. 



Soon I'll make the conrod and piston. Have got some 7075 aluminium which I intend to use for the piston.
I'm curious about the gudgen pin location. Have seen some drill in the centre (in relation to the height) vs some drill at the bottom. Is there any significance to this? 

Cheers

Andy


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## gbritnell (Apr 15, 2016)

Hi Andy,
If worse comes to worse you could set the crank back up in the lathe and turn down a section of it then make an extension and press and Loctite it in place. If you go that route I would make the extension shaft a little larger than the finished diameter of the crank and drill a center hole in the end. Once pressed in place you could use the center and then turn the shaft to the finished diameter. 
gbritnell


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## Parksy (Apr 15, 2016)

Thanks George. I like that idea.

Made the piston today. Have worked a lot with 7075 sheet metal on aircraft but have never machined it before and it is just wonderful stuff. Pity about the price tag.

Two ring groves which I'll soon make some cast iron rings.


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## Parksy (Apr 16, 2016)

Ringed it. Made heaps of spares which I never needed. It so easy when it's only one cylinder.




Currently working on the conrod. Found some 431 stainless. This stuff isn't that bad to machine and has very good strength characteristics.


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## Parksy (Apr 17, 2016)

Conrod is well under way. Just a few small milling operations to do then will clean it up and polish it.


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## 10K Pete (Apr 17, 2016)

Looks really good! At this rate it should be running soon.

Pete


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## Parksy (Apr 18, 2016)

Thanks Pete. That's the plan. 
Loosely put together for a quick pic. I need to make some split bushes for the big end. I have heard how people cut the material in half then soldier it together and turn on the lathe to required dimensions. Does this method present issues with regards to having both halves of equal size?


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## 10K Pete (Apr 18, 2016)

I don't think it matters how the two halves are held together and it's my experience that if the split is within 10 or 15 thou of actual center it's good.

Solder, glue or in some configurations nothing but holding the pieces in the chuck
or collet, whatever gets it done.

That's a great looking engine!

Pete


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## petertha (Apr 18, 2016)

Parksy said:


> I need to make some split bushes for the big end. I have heard how people cut the material in half then soldier it together and turn on the lathe to required dimensions. Does this method present issues with regards to having both halves of equal size?


 I made some finicky split lap clamshells using this technique which probably amounts to similar shape you are contemplating. One of the experiments was aluminum so soldering wasn't an option. Crazy glue & Locktite seemed to hold things together. Joint parted with some gentle torch heat. You cant get too aggressive with cuts, but that's probably more a function of how things are being held in the chuck/collet.

ps, some guys are using silver sheet for this application which are clamped between the split rod segments. Silver is apparently available through jewelry making suppliers. I guess this method can yield a very thin bushing equivalent & saves you a separate OD/ID split bushing which might be a finicky little bugger depending on the size. I've also heard  of bronze sheet but never really explored this option in terms of stock thickness & cost etc.


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## deverett (Apr 21, 2016)

petertha said:


> I made some finicky split lap clamshells using this technique which probably amounts to similar shape you are contemplating. One of the experiments was aluminum so soldering wasn't an option. Crazy glue & Locktite seemed to hold things together. Joint parted with some gentle torch heat. You cant get too aggressive with cuts, but that's probably more a function of how things are being held in the chuck/collet.
> 
> ps, some guys are using silver sheet for this application which are clamped between the split rod segments. Silver is apparently available through jewelry making suppliers. I guess this method can yield a very thin bushing equivalent & saves you a separate OD/ID split bushing which might be a finicky little bugger depending on the size. I've also heard  of bronze sheet but never really explored this option in terms of stock thickness & cost etc.



Would copper be a substitute for bronze?  It is available in 0.1 mm (0.004") thickness from our favourite online auction house. eBay item number:
311450892213.

Dave
The Emerald Isle


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## Parksy (Apr 22, 2016)

Almost completed one flywheel. Need to mount it to the rotary table and drill some holes to remove some mass from the center and make it look nicer. Also had a go at making a taper lock. Not too difficult at all and works very well.
Will make a second one.









The flywheel is 100mm in diameter which is quite large for the mini lathe. Getting a bit of chatter which I'll clean up later.


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## Parksy (Apr 23, 2016)

Half way through another flywheel. The drive belt on the lathe isn't coping too well with the steel and the large diameter so I'll need to replace it before I break it.



Have made big and small end bearings for the rod and have started on the head. The split bearings for the big ends was very straight forward. Ended up soldering two halves of LG2 bronze together and turning it to required dimensions. 
Here's a quick pic of what it will eventually look like. The flywheels are not completed nor attached.



Similar to the "tiny" engines but larger.


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## goldstar31 (Apr 23, 2016)

I'm not into this now but I would have thought that recovering the bearing metal from scrap car shell bearings would stand up better than silver.  Silver really needs to alloyed to get durability.

Bearing metal once recovered, can be 'tinned' onto  steel and then machined.  I tinned and whatever the worn out feed screw nuts on an old Pools Major lathe and the lead indium bearings came from the worn out shell bearings on my old Mini Cooper.  You can do it all in decent baked bean can and then a bit of fireclay as a mould.

Which brings me to my question. I have a rather large stock of silver amalgam. It came out of a lot teeth. The gold platinum alloy, my late wife re-cycled into a jewellery ingot. Any bright ideas about the amalgam recovery? 

Regards

N


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## mayhugh1 (Apr 23, 2016)

I think if you're going to use silver you want to use pure soft silver. An alloy like Sterling is too hard. You want a metal that is very soft and will easily conform to the shape of the journal. I used silver for the shell bearings in my Merlin, but that was really an exercise in novelty. I machined press dies to form the shells which was a lot more work than the more common method of soldering/unsoldering bronze half shells. The alloys used on the surfaces of automotive bearings are even softer than silver, but their embedding properties (ability to embed grit and reduce journal scratching) are superior and probably one of the reasons silver isn't more commonly used in high performance applications. Ron Colonna used very thin pure silver sheet as an overlay to the bearings in his Offy, and that seems to have worked out well fir him. My advice for a first effort is to stick to one of the common modeler's techniques for making them and to use bearing bronze. Lot's of single cylinder model engines even get along well without separate bearings. - Terry


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## petertha (Apr 23, 2016)

Some silver bearing discussion here.
http://www.modelenginemaker.com/index.php?topic=5123.0

and here post #139 onward
http://www.homemodelenginemachinist.com/showthread.php?t=24153&page=14
George mentions down the thread, Ron's Offy engine apparently uses this method

* you beat me by a nanosecond Terry, thanks for more qualified reply *


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## Parksy (Apr 24, 2016)

Thanks all for your input. More knowledge the better.

Finished the crankshaft and pressed in the small end bearing. 



Made a base for the engine to sit on. 



Drilled some holes into the head where I'll press fit some valve cages. 
Ran the bottom end assembly in the lathe to run the rings in. 
Getting there. Starting to get to the nitty gritty stuff


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## Parksy (Apr 29, 2016)

Gday all

Just a quick question, what sort of duration should I go for with regards to the exhaust cam?

Cheers

Andy


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## Parksy (May 1, 2016)

Flywheels are almost completed. They are quite a time consuming part, and I only drilled the mass out of the centre. Would hate to imagine how long it takes for those who mill the spokes. Anyway, I've made the taper locks for both and the intent is to fit it to a dialled in shaft fitted to the lathe and true up the flywheels if need be, then clean them up and plate in nickel. 




Cheers


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## Parksy (May 6, 2016)

I did a lot of research on gear cutting and have purchased the necessary cutters for the job. Unfortunately they are coming from China and I'll be waiting weeks, so I got impatient and bought some gears off eBay. They came hardened so I annealed them and modified them somewhat to suit my application. I milled a cam onto the large spur gear and this will operate the exhaust valve. 



Made and pressed some valve cages into the head and drilled the intake and exhaust ports. Valve seat angle was cut at 45 degrees. 



I've decided to go with a Hall effect style ignition. I've noticed in some builds that people install a magnet into the flywheel and not off a cam gear/drive.  Is there any reason for this? My flywheels are steel, is this a bad material to install a magnet into?

Cheers and thanks for reading.

Andy


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## GailInNM (May 6, 2016)

Looking FINE Andy.
Cam versus flywheel for the magnet mounting?  Each has its advantages so it comes down to personal choice. If the magnet is mounted in the cam you have to make the Hall effect mount adjustable to set the timing and if it is mounted in the flywheel you can fix the Hall effect mount and adjust the flywheel to set the timing. When mounted in the flywheel you will have a wasted spark but if you're using a CDI ignition systems such as from S/S machine than the current is so low that this is not a particular disadvantage.

On my engines I kind of like the flywheel mounting for two reasons. One for the simplicity of the mount and second I can hear the spark through the open exhaust valve in the wasted spark position of the flywheel. This lets me know the ignition is working and the plug is not fouled as well is it is a convenient way to set the spark timing. The timing thing is not too critical because I normally add a LED indicator to the ignition circuit. It only takes one resistor plus the LED and convenient for timing and to know that my battery is not dead.

Mounting the magnet in steel, you need to have a sleeve around the magnet to prevent tje stee from "shorting out" the magnetic flux. Any nonmagnetic material will work such as aluminum, brass or plastic. It should have a fairly thick wall but is not critical. For convenience, I have used a 3/16 OD sleeve for `1\8 inch diameter magnets. The magnet can touch the bottom of the pocket or not - your choice.
Gail in NM


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## petertha (May 6, 2016)

Parksy said:


> , so I got impatient and bought some gears off eBay. They came hardened so I annealed them and modified them somewhat to suit my application. Andy


 
I might find myself going down this same path. Can you elaborate on what the purchased gears were described as material/hardening state wise & your procedure for annealing? Then after your mod machining, will they stay in this state in the engine, or can you re-harden?

Thx - Peter


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## Parksy (May 6, 2016)

Thanks Gail in NM. That helps a lot!

Peter, here's a link to the seller I used for the gears
http://www.ebay.com.au/itm/MOD-1-0-...CNC-MACHINE-/290782258796?hash=item43b3f9266c
I'm not sure what metal they used to make the gears but the teeth came case hardened and were very tough. Wasn't very nice to cut on the lathe even with carbide.
There wasn't any thing technical about how I annealed it. I positioned some bricks around the gear to retain the heat, heated it cherry red and left it till the next day. It cut wonderfully after this. I will harden it again.


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## Parksy (May 8, 2016)

Made an exhaust out of stainless. I didn't like the look of a curved pipe so I cut it and brazed it back together.
I tried to polish it but the black stuff on the surface is hard to remove. Even with a file! Any tips on that one?


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## Parksy (May 9, 2016)

Ok so persistence is required to remove the black crap from brazing. Most of it is removed and I'm happy. Havent done much brazing before and I found the process quite simple and satisfying. I look forward to making more difficult parts next time.


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## Brian Rupnow (May 9, 2016)

Parksy--You may have trouble getting a good valve seal with such a deep chamfer on the valve seats. I have built  a number of i.c. engines, and find that the best results for valve sealing come from a seat that has a 45 degree chamfer of only .015" to .020" deep. that way, when using a steel valve in a brass seat it only requires a bit of lapping with 600 grit for a good "line contact" seal. I have never been able to get the valves to seal properly on a chamfer as deep as you show in the picture.---Brian


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## Parksy (May 10, 2016)

Thanks for the tip Brian! I have heard about making the valve seats with a very thin contact line, but Ive used the same method as I did with my previous engine. Mind you, the valve and seat had a difference of 5 degrees between the two and after a 10min lap I was able to get a good seal. The previous engine had the stems of the valves tapped and a nut installed, so when the springs and washers were installed, a drop of oil onto the stem and some lapping paste onto the seat, a socket installed into the chuck on the mill and I was able to lap as much as I needed until I was happy. And just using the force applied from the valve spring was more than enough.

Cheers


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## Parksy (May 13, 2016)

Couple a valves knocked up today out of 316 stainless. Not too many dramas with these. 10mm stainless rod prodruding just enough from the chuck and turned down to almost final dimension in 10mm lots to avoid the stem deflecting the cutting tip. Once the stem length was achieved then some wet and dry backed with a file to finish to final dimension and remove and ridges. Worked well and this is the method I was advised by several members on this site. Thank you!


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## Parksy (May 20, 2016)

Drilled and tapped a spark plug hole. I cheated with the spark plug and purchased a 1/4 32 plug off eBay.


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## Brian Rupnow (May 20, 2016)

Nice work Parksy--I'm still following.---Brian


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## Parksy (May 22, 2016)

Thanks Brian.

Progress has been good this weekend. Holes have been drilled and tapped into the head to support what will soon be the carburettor on the bottom. Rocker gear is mostly complete apart from a few small pins. I've made the rocker out of mild steel which I've nickel plated for that added protection. The cam tappet is a roller bearing which operates nice and smoothly. Do I need to harden the cam if I use the roller bearing?

Thanks for looking

Andy


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## 10K Pete (May 22, 2016)

That's a beautiful engine, Andy!

Pete


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## Barnbikes (May 22, 2016)

Let me second the beautiful engine comment. 

Just wondering if you should put a cooling fan on it. Rather large head and smaller gaps between cooling fins on cylinder are going to retain the heat and it is going to get rather hot after a very time of running. Just a thought.


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## Parksy (May 22, 2016)

Thanks guys and cheers for the heads up Barnbikes. I may have to run it with a desk fan blowing into it.

Cheers

Andy


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## Brian Rupnow (May 22, 2016)

I never hardened any of my cams. Unless your engine is going to run 24/7, it simply isn't necessary. Engine looks very nice.--Brian


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## gus (May 24, 2016)

That was a very beautifully made Engine. Will be hard to match your workmanship.


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## Brian Rupnow (May 25, 2016)

If it runs---Then it is beautiful. If it runs in hit and miss mode, it won't need a cooling fan, because during the miss cycles it pumps ambient temperature air thru the cylinder which will cool it adequately. If it doesn't run, then it is simply a beautiful piece of art.


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## Parksy (May 27, 2016)

Thanks all. These comments mean a lot to me as I haven't been machining for very long at all. But my interest and motivation is very high.

Anyway, I lapped the valves into their respective seats today and Brian, your comments about having issues with sealing were on my mind the entire time. But I got them sealing well. Because I have used a nut on the end of the stem it is easy to spin the valve with a socket in the milling machine using only Spring pressure. A drop of oil on the stem and fine valve lapping paste onto the seat, then cleaned up thoroughly then repeat with metal polish, then cleaned thoroughly again and then done with wd40. Strangely enough, the wd40 at the end just makes thing work better. Maybe it cleans the contact surface at a micro level, I'm not sure, but I find this step crucial and recommend it to everyone who has trouble sealing valves. When the wd40 doesn't turn black anymore, it's a good indication that it's nice and clean.


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## petertha (May 27, 2016)

Good luck, look forward to the run. The WD-40 comment is interesting. When I was mucking about with lapping compound I found WD-40 to be one of the better things to wash the lapping compound off for some reason. Acetone or methanol or alcohol dilutes the greasy carrier goop but WD40 seemed to make it shiny & clean with very little effort. I'm starting to think WD40 is good for mosquito bites & arthritis  Anyway your 'black' might either be highly diluted micro polish left over, or no polish & simply metal on metal lapping?

I wrote about this in some other post but when I was testing valve seal against my vac gauge I think the best results came from polishing the valve face, but maybe for the wrong reasons in my case. I feel like yes my 1200 paper was indeed making it super shiny, but maybe putting an ever so slight radius to what is supposed to be a linear 45-deg face. And the nice seal was occurring because it was finding a tangent contact point as a result of this arc. Just a hunch, could be off base.


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## Parksy (May 28, 2016)

Cheers Petertha. Not far from attempting a start. Ignition is set up and working nicely, the valve train is completed and linked together with bronze pins. Gave the flywheels a spray with paint. And the carby is about half way there. 
I have a question about Spring pressure with compression springs. I need the intake valve to open with less pressure than the exhaust. If I use the same Spring, but have the exhaust under more tension than the intake, then should this setup be ok? I hope this question makes sense. It seems obvious, but I could be overlooking something.


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## Brian Rupnow (May 28, 2016)

The atmospheric intake spring needs to be the lightest possible spring you can get that will still pull the valve closed once you have opened it by pressure on the end of the stem with your finger. Something with .010" to .013" wire size. The Exhaust spring can be much more robust, as it not only has to be capable of pulling the valve tightly shut, but must also ensure that it rocks the rocker arm and holds the end of the push-rod firmly in place against the cam at all times (except when the cam is not influencing the push-rod bearing at all--then it needs about .005 to .009" clearance between cam and bearing to allow the valve to seat tightly) . The exhaust spring also has the mechanical cam to compress it. It can be .022" to .025" wire size. The intake valve is depending on  "ambient" air pressure only to open the intake valve against the spring pressure, it so must be very light.


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## Parksy (May 29, 2016)

Well today has been a very exciting day. I finished off the carburettor. I've never made one before and I only went off a few pictures I quickly googled to get a basic idea. I remember seeing a picture of a sewing needle used as a metering valve so I used this method. 






Installed the carby then realised that the engine could possibly run. So I hooked up the ignition components and gave it a spin. No luck by hand. Tried a Dremel with a rubber wheel and this worked well. Except that it ruined the paint job on the flywheels. Never mind, easily fixed. Got lots of pops and smoke and a bit of frustration. But then an hour or two later of tinkering and I found the sweet spot!! It runs!! I remember reading about the satisfaction that is felt when an engine first roars into life by other members and now I know the feeling. Truly satisfying!
https://youtu.be/TFNfYNB3k7k
[ame]http://www.youtube.com/watch?v=TFNfYNB3k7k[/ame]
I will make a wooden base to house the electronics and make a nice looking fuel tank to rest on top somewhere. 

Cheers all!


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## Brian Rupnow (May 29, 2016)

Congratulaions--If you send your "real" email address to brupnow @rogers.com, I will send you plans for a carburetor with a throttle and for a carburetor without a throttle which is suitable for hit and miss operation.---Brian rupnow


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## Parksy (May 29, 2016)

Thank you Brian, I appreciate this a lot. I tried that email (without the space of course) but it doesn't seem to work for me.
My email address is apthegreatis at hotmail.com. Don't judge me on the email, I've had it since I was 15 years old.


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## Brian Rupnow (May 30, 2016)

Did you get the emails I sent you?---Brian


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## Parksy (May 30, 2016)

Sure did. Thank you very much! They will come in handy.


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## gbritnell (May 30, 2016)

Great job Parksy. I know the feeling when you first get them running.
gbritnell


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## mayhugh1 (May 31, 2016)

Your workmanship and attention to detail is top notch. It's a really good looking model. Congratulations! - Terry


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## Parksy (May 31, 2016)

Thanks George and Terry. I appreciate the kind words.


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## Parksy (Jun 4, 2016)

Have got it mounted to a wooden base which houses the electronics and a fuel tank. Made out of brass and soft soldered the caps and filler onto.


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## Parksy (Jun 5, 2016)

I didn't like the painted flywheels so i sandblasted them back to bare metal and polished the outer rim. I then nickel plated them and i'm happy with how they turned out. The inside part of the flywheel also has plating on it, but because of the rough surface, it doesn't appear the same as the outer rim.


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## 10K Pete (Jun 5, 2016)

Looks great Andy! But then I'm a big fan of satin nickle.

Pete


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## Barnbikes (Jun 5, 2016)

New base = new video.


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## el gringo (Jun 5, 2016)

Hi Parksey;

I haven't participated in this forum in a while, but as I got ready to start a thread on a build I started in 2014 and have since completed, your current build caught my attention. 
My build is amazingly similar to yours although the quality of my work pales in comparison. I built mine as a hit and miss and I can show detail pics of the governor I devised for it if you are interested...I will post the relative build thread soon.


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## Parksy (Jun 6, 2016)

Thank you all.

El gringo, that is strangely familiar. I like it. Usually I'll see something and build something similar based on what I've seen, but this one I just plucked from thin air. I'm thinking about a separate governor that won't use the crankshaft, but I'll have to think about it.


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## Parksy (Jun 7, 2016)

Here's another quick video. I haven't tuned it and it's not running at its best but the flywheels look good. I still can't hand start it. It has good compression and this may be the cause.
https://youtu.be/npNY9Xn30us
[ame]http://www.youtube.com/watch?v=npNY9Xn30us[/ame]


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## Parksy (Jun 10, 2016)

Couple of questions. The engine has a lot of kick. I have a quick video of myself holding the engine while running.
https://youtu.be/mSJpisyhHuQ
Will lowering compression help reduce this?

The carby doesn't appear to draw fuel and requires the fuel tank to sit higher than the carby inlet. It's a very basic carby with a Venturi and metering valve. Is this a normal thing?

Cheers

Andy


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## Brian Rupnow (Jun 10, 2016)

Parksy said:


> Couple of questions. The engine has a lot of kick. I have a quick video of myself holding the engine while running.
> https://youtu.be/mSJpisyhHuQ
> Will lowering compression help reduce this?
> 
> ...


Compression should be about 5 or 6 to 1  Carb should suck fuel up at least 3/4" if it is working right. tank above carb is a no-no--causes flooding and potential fires.


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## Parksy (Jun 11, 2016)

Thank you Brian. Turns out the carb works just fine, I just needed to play around with it. It even self primes itself. I will change the fuel tank mounts and set it lower. For some reason I was under the impression that the tank needed gravity to assist. 
Runs better with the tank sitting lower also.

Cheers


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## Brian Rupnow (Jun 11, 2016)

You asked the other day about hand starting your engine. If the engine sets for a while, gravity will make the fuel flow back into the tank, and your wrist will fall off before you get it to hand start. To prevent the fuel flowing back into the tank, a great solution is a little ball valve setting vertically in the gas line. Something about 5/32" diameter. The suction caused by venturi effect in your carb will lift the ball off it's seat and suck the gas up to the carburetor, but when the  engine is not on the intake stroke or is setting idle, gravity pulls the valve back into it's seat and prevents the gas from backflowing into the tank. This makes hand starting (or any kind of starting) much easier. 
http://www.homemodelenginemachinist.com/showthread.php?t=24778&highlight=ball+valve


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## Parksy (Jun 11, 2016)

Thank you again Brian! That is perfect!!


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