35cc "V" Twin

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Ghosty

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Hi All,
Made a start on a V Twin today, first I scanned the plans into comp, and converted to pdf's so I can print working sheets with out damaging the originals, I need to order more material, as I don't have enough for the cylinders/ heads/ crankcase, machined the twin rods, Complete, still looking at changing it to a OHC from OHV engine, will look further as I get into the build, the rod is same as the single OHC that I just finished, except that the OD of the ends of the rod are larger.
Plans can be found at Baupläne Modellmotore - Online-Shop der Fa. CAD+Modelltechnik Jung
Cheers
Andrew
 

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Ghosty

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Cut a some of pieces from stock and machined up a couple of piston blanks, I have several things on this morning so will machine later.
Cheers
Andrew
 

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Ghosty

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Hi All,
Got the pistons done, weather closing in and started to rain, so I won't get as much done as I would like
Cheers
Andrew
 

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Jones

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Looking good mate!
Why not just add the extra relief to the pistons in the correct direction? I can't see any downside to having the side relief as well, most full size engines relieve the sides of the pistons to decrease friction.
 

Ghosty

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Looking good mate!
Why not just add the extra relief to the pistons in the correct direction? I can't see any downside to having the side relief as well, most full size engines relieve the sides of the pistons to decrease friction.
I have all ready machined the new pistons, so it was something that kept me going. I know about modded pistons, shown is a piston that I run in ASP 120 FS singles.
Cheers
Andrew
 

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Ghosty

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This looks veeeeery interesting. Hope you don't mind if I tag along for the ride.

Are you building something to power with it ???
No don't mind at all. No not powering anything with it, they are way too heavy and don't have the power of other engines. I just build them to keep active, walking or other exercise is difficult with the damage to my body from an MVA 40 odd years ago.
Cheers
Andrew
 

Ghosty

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Hi All,
Got the rear crankcase plate almost finished, now to swap the 4 jaw back to a 3 jaw and center, so that will be the end of the day.
Cheers
Andrew
 

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Ghosty

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Hi All,
Material turned up for the crankcase and cylinders, Got the pieces cut, and squared up one piece for the crankcase, then cut the crankcase block cut in half. Have to clean up and size the 2 crankcase half's, then the real fun starts.
Cheers
Andrew
 

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Ghosty

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Hi All,
Well, lots of different setups and machining, but have a basic crankcase block. The rear housing that I made the other day even lines up with it. Still have to drill for alignment pins, will do 2 on one side and only one on the other. The assy is still 4mm too long, will fix when machining the bores.
Cheers
Andrew
 

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Ghosty

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Well I can't bet the correct bearings from my bearing supplier for the cam, and my boring bars don't have enough offset to machine out the center of the crankcase. I have ordered some 3mm HSS to make tips for a boring bar, and ordered the bearings, looks like I start on the cylinders tomorrow, I have the material for them.
Cheers
Andrew
 

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stof

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Dear Cogsy

I have made this engine along with my mate. several problems we had and fixes and observations if you are interested were


1. the piston to cylinder fit as specified, tolerance is to tight . It seizes. So both of as had to increase the tolerances slightly.
2. the crank shaft pin needs to be a very tight fit preferably a press fit other wise it moves . I had to redo this several times.
3. there is significant wear from the roller bearings on this pin and needs to be hardened, use hardened drill pin perhaps.
4. the gudgeon pin also wears significantly for the same reason . The little end of the conrod deforms as well, my second conrods had phos. bronze inserts that solved this problem.
5 Be very careful to get a press fit on the valve sleeves , as the lip is to close to the cylinder head and mine leaked , so valves would not seal due to this. I changed the exhaust and inlet diameter to 9 mm to give more clearance on the second heads I had to make.
6. very nb. cut the m10 thread into the cylinder head for the exhaust and intake bushes before making the cooling fins as you will break the fins
if you attempt to thread them after .
7. I had problems with the propeller . The spiked pins stripped the bottom of the wooden prop and I need to solve the problem by using 3m screws from front to back of the prop through a washer avoiding the use of prop cowl ,going rather for a custom nut.. I am able to hand start this engine easily , so the cowl was not necessary for electric start. Runs at 7200 rpm. after above mods .
8. I used cast iron rings instead of steal [en 8 equivalent]. As my first set of steel rings did not work well.

So there are my thoughts on experiences with this engine for what they are worth

Regards.
 
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