# Ellery V-Twin 100cc Design & Build



## cbooth (Apr 12, 2020)

Hi all,
Thought I would put progress to date of my own design engine V-Twin,  all things going well she will be used for an RC plane I am building.
The engine specs so far are:
Type: V-Twin gas
Capacity: 100cc (2 x 50cc)
Stroke: 3.9cm
Bore: 4.0cm
Compression Ratio: 8.5
Ignition: Spark

I've been designing it in Autodesk Inventor which makes it really easy to take of plans and dimensions.


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## cbooth (Apr 12, 2020)

I've been working on this off and on for about 6 months  now and have most of the main casing elements done.


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## cbooth (Apr 12, 2020)

a few bits of it anodised


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## cbooth (Apr 12, 2020)




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## WOB (Apr 12, 2020)

Looks good, but I'm curious why you picked a 90 deg. twin instead of a 180 deg. twin considering that the vibration of the 90 will be considerable and the 180 would be zero( assuming a 180 deg. crank)?


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## cbooth (Apr 12, 2020)

WOB said:


> Looks good, but I'm curious why you picked a 90 deg. twin instead of a 180 deg. twin considering that the vibration of the 90 will be considerable and the 180 would be zero( assuming a 180 deg. crank)?


It's 90° V so technically has perfect primary balance, aka Ducati. Also I wanted a V to suit my plane design. The heads will stick out of the cowling.


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## awake (Apr 12, 2020)

Beautiful work! I'm curious about the needle bearing in the rod - what type (number) of bearing is it?


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## cbooth (Apr 13, 2020)

awake said:


> Beautiful work! I'm curious about the needle bearing in the rod - what type (number) of bearing is it?


Thanks Andy, they are HK1010 Drawn Cup Needle Bearings


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## Sprocket (Apr 13, 2020)

What is it going to power? 100 cc? That's like a small motorcycle engine!


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## bruski (Apr 13, 2020)

That engine and your skills are perfect. If you should put together a drawing package, I would like to purchase a set from you. Great work!
Thanks,
Bruski


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## cbooth (Apr 13, 2020)

Sprocket said:


> What is it going to power? 100 cc? That's like a small motorcycle engine!


my version of the Riley Model B. 100" wingspan


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## cbooth (Apr 13, 2020)

bruski said:


> That engine and your skills are perfect. If you should put together a drawing package, I would like to purchase a set from you. Great work!
> Thanks,
> Bruski


Thanks Bruski. Plans are pretty much finished, but wouldn't like to release until I have finished mine and get it running. I occasionally find bits when I am machining that I need to make alterations to on the drawings.


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## awake (Apr 13, 2020)

cbooth said:


> Thanks Andy, they are HK1010 Drawn Cup Needle Bearings



Thanks!

I think I recognize the pilot in the airplane - that's "Mini-me," isn't it? (From the otherwise forgettable Austin Powers movies.)


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## cbooth (Apr 13, 2020)

awake said:


> Thanks!
> 
> I think I recognize the pilot in the airplane - that's "Mini-me," isn't it? (From the otherwise forgettable Austin Powers movies.)


close, it's actually Bruce Willis. I downloaded the file and 3D printed him


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## awake (Apr 14, 2020)

Hmm ... I'm trying to think if I've ever seen Bruce Willis in a movie where he is in a plane like this ...


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## cbooth (Apr 19, 2020)

today I got the rear crank done. Found it really difficult to get a good finish on the EN16








Also got the first piston sleeve done from Cast Iron, much easier to machine. Made an error by rushing and gouged a mark withdrawing the work piece. Fortunately it'll be well below the piston rings so should not affect anything.


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## a41capt (Apr 20, 2020)

This is beautiful workmanship! Both engine and airplane are exquisitely executed. 

100cc?  FYI, I took a 3rd place in my first motorcycle race in 1967 on a 60cc bike.  I would’ve loved to have had those extra 40cc, not to mention having them in a V-Twin configuration!

You sir, are an artist!

John W


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## Peter Vivian (Apr 21, 2020)

Amazing work and I'm loving the 'plane, just back into aeromodelling after a 45 year gap!


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## bluejets (Apr 22, 2020)

cbooth said:


> Found it really difficult to get a good finish on the EN16



Have you tried a vertical sheer bit approach..??
Link.............
Vertical Shear Bit


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## bhouin (Apr 23, 2020)

Great stuff here. Just curious did you draw your on plans for the plane?


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## cbooth (Apr 23, 2020)

bhouin said:


> Great stuff here. Just curious did you draw your on plans for the plane?


Thanks, yes the plane is from my own plans also, however the style of design is not mine. The original is by the Gratner Brothers. I just loved the look of it so much I wanted one. Mine is not going to have the wood vaneer, but will be more classic racing red style.


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## cbooth (Apr 23, 2020)

Peter Vivian said:


> Amazing work and I'm loving the 'plane, just back into aeromodelling after a 45 year gap!


Thanks Peter. 45 years!, I've been flying and model engineering for about 4 years, a long way to catch up


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## cbooth (Apr 23, 2020)

a41capt said:


> This is beautiful workmanship! Both engine and airplane are exquisitely executed.
> 
> 100cc?  FYI, I took a 3rd place in my first motorcycle race in 1967 on a 60cc bike.  I would’ve loved to have had those extra 40cc, not to mention having them in a V-Twin configuration!
> 
> ...


Thanks John. I made the first piston yesterday and it made me realise how big the thing really is.


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## cbooth (Apr 23, 2020)

something like this....hopefully.


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## a41capt (Apr 23, 2020)

Well, as a retired firefighter, I’m pretty partial to red.  I think it’s the perfect color!


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## Cogsy (Apr 23, 2020)

bhouin said:


> Great stuff here. Just curious did you draw your on plans for the plane?


Do you not do this? I print out a workshop copy of my plans which I use to document changes, actual finished dimensions I've achieved, calculations or even just notes to myself as I go. At the end of the job my workshop plans are scrappy and sometimes barely readable but they've finished their job and can go in the bin (or saved in a pile for future reference if need be). I never use my 'good set' to work from.

Edit: I think I misread a typo in your post - I read "your on plans" as " on your plans"...disregard my rambling


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## a41capt (Apr 24, 2020)

Cogsy said:


> Do you not do this? I print out a workshop copy of my plans which I use to document changes, actual finished dimensions I've achieved, calculations or even just notes to myself as I go. At the end of the job my workshop plans are scrappy and sometimes barely readable but they've finished their job and can go in the bin (or saved in a pile for future reference if need be). I never use my 'good set' to work from.
> 
> Edit: I think I misread a typo in your post - I read "your on plans" as " on your plans"...disregard my rambling


Cogsy, I’m with you!  My plans, scribbled drawings and notes, are usually covered in greasy/oily fingerprints and smudges.  Usually only fit for the trash can, but they’re all there and, like a trail of bread crumbs, lead me back to where I’ve been!

John W


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## bhouin (Apr 24, 2020)

Good catch. That should have read “your own plans”


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## cbooth (May 26, 2020)

sorry, it has been a while since I posted. Have made some further progress.
Pistons, gudgeon pins done.





Crankshaft (EN16) done.





Was waiting for the pulley and gear until I designed the tensioner. Seems to work ok










Another part I was waiting for was the carb. After a lot of deliberation (found it really hard to find out much about carbs and Walbro numbers) I went with an OS GF40 carb which is also Walro.
Made a splitter and an inlet trumpet then anodised.





My original plans for the both the inlet and exhaust was S/S. but came across 2 problems. My tube bender will not give a tight enough bend radius, and I cannot silver solder. Tried a few times and just can't get success. I suspect my gas torch is not powerful enough. So have changed the strategy at least for the inlets. Made these out of 2 parts aluminium and brazed together. it took quite a while to design the parts due to the double angles, but thats where drawing it in Autodesk Inventor really helps.









A while back i also partially assembled it and let it out in the sun.


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## a41capt (May 26, 2020)

Wow, I sure am hoping you’re planning on a video of that monster running!  That is nothing short of impressive!!!

Thanks for sharing,
John


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## gdrhbb (Aug 6, 2020)

Hello
Is your plan going to be sold？


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## Brian Rupnow (Aug 6, 2020)

Nice machining and super nice cad work. I'm a Solidworks guy myself, but Your Inventor is doing a superb job.---Brian


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## cbooth (Aug 8, 2020)

gdrhbb said:


> Hello
> Is your plan going to be sold？


Hi, I am not sure yet. I need to get it working first. Not too much more to do. Cam shaft and rings.


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## cbooth (Aug 8, 2020)

Brian Rupnow said:


> Nice machining and super nice cad work. I'm a Solidworks guy myself, but Your Inventor is doing a superb job.---Brian


Thanks Brian, I only use Inventor as I have access to it through my work (although I understand it can also be downloaded freely for hobby use). I have also been playing with Fusion, which is similar in approach to Inventor. I have been using it to design parts for my RC plane and then cut out on my MPCNC.


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## SailplaneDriver (Aug 9, 2020)

Outstanding craftsmanship! My hats off to you.


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## PRiggs78 (Aug 9, 2020)

Very nice execution.  Those heads protruding from the cowl will look mean. 100cc is a whole lot of power for that plane!  

You running any CNC machines or is this all manual?


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## Monster_Robotics (Aug 10, 2020)

Very nice work


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## Moldmaker (Oct 22, 2020)

Love this!! Beautiful work!


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## bobden72 (Oct 23, 2020)

cbooth said:


> sorry, it has been a while since I posted. Have made some further progress.
> Pistons, gudgeon pins done.
> View attachment 116594
> 
> ...


Very nice workmanship looking real smart.  Am I right in thinking that Walbro carbs have a built in pump operated by the engine suction or am I completely wrong.  Just something in the back of my mind tells me so.


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## davidyat (Oct 23, 2020)

*a41capt, you say you raced motorcycles in the 60's. Did you race desert? I raced in sanctioned events in the early 70's in the California Mojave Desert. Here are a couple of pictures taken of me during a couple of events. I used 175 Yamaha's.






Grasshopper*


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## Roberto (Oct 24, 2020)

bhouin said:


> Good catch. That should have read “your own plans”


Awesome engine workmanship 
Where can I get the plans to make one too?
Keep up the great work


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## Werkstattkrabbe (Oct 25, 2020)

Hello, 
I join in, I am also enthusiastic about the work on the engine.
When everything is finished, I would also like to acquire a drawing.


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## SPOTTER (Oct 25, 2020)

Bravo, you did a great job, where is it possible to buy the project to build this engine?


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## cbooth (Nov 15, 2020)

Well it feels like an age since of worked on this. Think I lost a bit of interest and needed to work on other things. But there is not actually that much more to get this finished and so hope to get this finished over the next few months.

Today I did some heat treatment of silver steel parts. Rocker arm, rocker pin, and tappets. Got some fire bricks after learning the hard way last time and getting spat at by exploding brick. Heated parts to deep red then quenched in some light oil. I then tempered in an enclosed BBQ at around 250°C for 30-40mins.
I've now way of knowing if the process has done what it should have, guess I will find out if the parts wear or break.







I also started making rings for piston 1 ( I have a slight difference is size between cylinders). I know there are probably better ways to do the rings, but I used what I think is the simplest method. ID and OD of ring to match the depth of slot in piston, and ID of bore respectively. Part off about 0.03mm over width. Sand and polish to fit snug in slot using 600 then 1200 grit on a flat piece of glass. Snap the ring in vice with a crisp knock with a chisel. Hold in an expanded condition and heat until it relaxes into that position and drops.


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## SPOTTER (Nov 15, 2020)

Congratulations again for the outstanding work,
can i know where i can buy the project?
thanks


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## cbooth (Nov 15, 2020)

SPOTTER said:


> Congratulations again for the outstanding work,
> can i know where i can buy the project?
> thanks


Thanks Spotter. Not sure if I will release the drawings, some of which are a bit of a mess now. Also i'd want to make sure it actually works first


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## a41capt (Nov 15, 2020)

Your ring making technique is exactly the way I do it.  I have found that when I make the piston (only cast iron of course), I make the piston longer, and after turning to diameter, turn the last section to the OD of the ring groove depth.  I then use a very narrow fiber dremel grinding/cutting disc in my dremel tool mounted to the tool post, and cut the rings off the end of the piston.

I used to break the rings as you do, but found that cutting them with the same dremel cutting disc makes the edge straight and smooth, which makes them drop off the section of rod smoothly when hardening and setting the spring.

Since the edges are already cut smooth from the dremel/lathe cut off operation, it just takes a little polishing with some very fine paper on the edges and done!


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## Canyonman (Nov 15, 2020)

Hi cbooth. I sure hope you decide to offer the plans. Great Project!  I would like to build this one
Ken


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## cbooth (Nov 16, 2020)

Here's a bit on the cam profiles.
I've been using a "Cam with draw" excel spreadsheet that someone has very nicely shared, to work out a cam profile. 




I have drawn this in cad to work out the crank to cam relationships.
So I have a total working angle of 135° for each lobe. The exhaust leads the inlet by 105°, and there is a 30° overlap.
Cylinder 2 will be offset by 135° (cam angle)


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## cbooth (Nov 17, 2020)

Heres the part drawn up now. Lets hope I've got the lobe angles right.


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## cbooth (Nov 28, 2020)

Well, got the cam made. used the mill, and happy with the results, EXCEPT i've got the cylinder 2 lobes at the wrong angles. 
Not a machining error, a drawing error...so  thats for the junk bin, and start again. Fortunately have just enough silver steel for another go


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## a41capt (Nov 28, 2020)




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## teeleevs (Dec 4, 2020)

Congratulations on a great job, keep up the good work.


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## MattMac (Dec 5, 2020)

Wow , that really is a nice looking engine


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## cbooth (Dec 6, 2020)

thanks guys. Made a new cam blank and i'm now ready to machine the lobes again.





I have now also made all the individual sections for the inlet from stainless steel, ready for silver soldering together. My silver soldering ability leaves a lot to be desired so will need to practice first.










Started to get the get the engine mount box with ignition, battery, and fuel tank ready. Will also add a servo for the throttle control.


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## Werkstattkrabbe (Dec 6, 2020)

Good evening,
concerning the carburetor, do you have a link for me?
Thank you.
Other than that, really great work. 
Eric


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## cbooth (Dec 6, 2020)

Hi Eric, the carb is from an OS GF40


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## cbooth (Dec 30, 2020)

Very happy today. Got the engine running, and it started pretty much first attempt. I only ran it for a few minutes and did not attempt to rev it. Unfortunately the tacho was not working (found a loose wire) so I didn't get a reading.
I was thinking it may need a fuel pump, but it seemed to draw the fuel through without even the crankcase pressure tube connected. 
I plan now to strip it back and double check everything, then start on tuning it as I did not even attempt to adjust the carb needles today.
Link to video below:
*Video of first run*


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## CFLBob (Dec 30, 2020)

Fantastic!  Sounds great, ran fine - when I read that part about adjusting the carb needles, I expected it to run at the same RPM for the video, but it sounded like you were able to throttle it up and down.  

This engine is an inspiration.  Looks beautiful, runs great, sounds great, it's the real deal!


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## Blacksheep (Dec 31, 2020)

What a beauty!
Congratulations


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## propclock (Dec 31, 2020)

Fantastic !  A most impressive snow blower. ! 
Do you plan on making plans available? 
The wt40 carb seems to be un available, darn. 
Congratulations!


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## CFLBob (Dec 31, 2020)

Is that two 100cc cylinders or 100 between the two?


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## H. K. Barrows (Dec 31, 2020)

No question you are A model builder. Red


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## ACHiPo (Jan 1, 2021)

Hats off!  Fabulous build!


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## Werkstattkrabbe (Jan 1, 2021)

Super class.
Congratulations.


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## Voltar1 (Jan 1, 2021)

Beautiful work!!!!
Might say that a diaphragm carb can only get fuel by the impulses working the pump side of carb. If you can pull fuel through that carb then your needle/seat is leaking


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## cbooth (Jan 1, 2021)

CFLBob said:


> Is that two 100cc cylinders or 100 between the two?


Its 50cc per cylinder. (well 49cc swept volume actually, but 100cc sounds better than 98cc  )
Stroke 39mm
Bore 40mm
Compression ratio 8.5


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## cbooth (Jan 1, 2021)

propclock said:


> Fantastic !  A most impressive snow blower. !
> Do you plan on making plans available?
> The wt40 carb seems to be un available, darn.
> Congratulations!


thanks. yes thinking of how I can best do this. It would be nice to gets some funds so I can start the next one.


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## Charles Lamont (Jan 1, 2021)

Just seen this. Lovely job.


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## mu38&Bg# (Jan 1, 2021)

Wonderful engine!

The Walbro carb used on the GF40 is the WT-1024. It's unlikely you'd find one anywhere other than an OS dealer. Walbro will design a carb for a specific application if you can fund it, as OS and Saito have done. With some effort, one can track down a suitable carb, though Walbro doesn't make it easy. In the past their site was more searchable. Four strokes really like an accelerator pump in the carb. The trick is finding a carb model which is currently available with the specs required and there is no resource which lists venturi size and other features.



Voltar1 said:


> Might say that a diaphragm carb can only get fuel by the impulses working the pump side of carb. If you can pull fuel through that carb then your needle/seat is leaking



This is not how a Walbro works. If there is venturi suction, the diaphragm opens the inlet needle. Obviously, suction also has to be great enough to pull fuel through the inactive pump. I would not try to fly a model with the carb setup like this, and certainly needle settings will change if the pump is working. It's working, seems quite well, as the carb is probably on the smaller side for the displacement.


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## cbooth (Jan 5, 2021)

I really struggled and got lost looking for a suitable carb. Was ideally looking for a WT-225 which is what the Kolm engines use, but could not source. Decided to try my luck with the GF40.

Still playing with the setup and have only managed to run it for a few more minutes as I need to be a bit respectful to my neighbors with the noise.
With the 26x10 prop, the range was 1300-4800 rpm which i'm pretty happy with without making any adjustments to the carb needles.

If i'm happy enough to put it in a plane I will likely use a pump which is common in commercial models (Kolm/Valach) of this type. That should at least provide a neutral pressure on the postivie side and let the engine suck what it needs.

For now I need to find somewhere remote that I can test and play with it (once lockdown finishes).
I also plan on trying a 24x10 prop.


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## cbooth (Jan 13, 2021)

Over the weekend I got her running again (sorry no video this time). I ran a 24x10 prop and it was comfortably pulling 5500rpm. The low end is still pretty lumping and it does not yet sit well below 1300rpm. 
Still some breaking in to do, but have now stripped her down for inspection. A satisfying feeling seeing all the parts laid out.


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## petertha (Yesterday at 9:07 PM)

Sorry for reviving an old post. @cbooth if you are still there, can you mention what kind of ignition system you used for this engine? And generally how is the engine getting on, particularly if it saw 'air' time!


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## Steamchick (Today at 12:59 AM)

Excellent build! Obviously you can design stuff as well! Bravo!
I am very impressed by your work.
K2.


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