Twin engine??

[butre]

Ive run into a photo of a guy who used two china girls and made a parallel twin on anouther MB forum....dont have the link though. BikeBerry has a photo on their facebook of a twin engined bike with a frame mounted 2-stroke and a rack mounted 4-stroke.

Why not put two pistons in one cylinder? Its been done before and would be the best solution.....

two pistons in one cylinder? are you referring to a twingle? there's no advantage to twingles. they're heavier, more expensive, and more complicated.

 

[AutOtaku]

If you just wanted two pistons on one bike, that be feasible other than that your right

 

[Steve Best]

Ive run into a photo of a guy who used two china girls and made a parallel twin on anouther MB forum....dont have the link though. <SNIPPED>.

That would work with both going to 2 sprockets on a single jackshaft.

Steve

 

[AutOtaku]

Though wouldnt a big problem with that be having both pistons hit TDC at the same time? Ive seen that brought up.....

 

[Steve Best]

Though wouldnt a big problem with that be having both pistons hit TDC at the same time? Ive seen that brought up.....

With both sprockets feeding a jackshaft you would never have both engined sync'd in any way. It really would not matter much. Occasionally vibes would be bad and occasionally they would be better. 2 independent motors working side by side.

 

[HeadSmess]

twingle isnt the only type with...hang on...twingles still use two cylinders, dangnammit!

mmm, opposed piston like a doxford or napier deltic... sheesh. then you got two crankshafts to deal with...

biggest issue i believe the twingles had was the fixed conrod, always had to flex a bit... why they never tried a forked big end, god only knows...

but they do have good scavenging characteristics, as one cylinder has the exhaust, one has the transfers... bit of ingenious porting /synching and you can run (finally!) forced induction that actually works! (thinking about plans i have somewhere for a model boat...two contra-rotating engines in one case with a combined head... no torque reaction, and suited to twin propshafts... otherwise, silly...)

still, way too much effort for the gains... oh, they were mad, 50+ years ago when every guy had a lathe and tried out new ideas...

 

[Steve Best]

I didn't know about the Doxford or Napier Deltic, thanks. I worked on an Allstate Twingle when I took shop in the 70s.
I saw a Junkers Jumo 6 cylinder opposed piston diesel AIRCRAFT (!) engine in a museum in Ottawa.
800hp and light enough to fly. Wow.

These engines are cheap enough and virgin canvass for many ideas. Wonderful place to learn.

Steve