Small bore 2 cycle engines.

[debgeo]

I am in process of building sidecar for the small engine class. I am looking for guidance on 125cc,250cc&350cc engines. What I specifically looking for is what manufacture [Honda Kawasaki etc] is best starting point for building into hi performance for Bonneville. I have searched on google and everyone seems to have a favorite. I am hopeing for information from builders that have experience in this area. As always THANKS in advance  GEORGE

[Nortonist 592]

Dave Minder ran a 350 Yamaha twin last year at El Mirage.  I think his best was 117 and the engine seemed to be reliable.  My choice would be a Yamaha from one of their quads.  Plenty of power, plenty of parts.  And from what little I know a fair bit of aftermarket parts. 


By weslake at 2010-04-21

[Jonny Hotnuts]

As far as the 125 & 250 goes I recommend the Aprila. They are modern engines, already designed to make HP and have the gearing. They race the poop out of them in europe and there is go fast stuff for them. Good luck getting your hands on one (they are around but not the easiest to find in the US).
An Aprila 50cc is what the Budfab guys are sporting with great results.


I think you can use the Banshee engine (yamaha 350 twin 2 stroke) but you have to call it an RZ350 (this is the bike it was used in). I am null in bike rules but I thought the engine had to be originally used in a bike, making an ATV motor illegal....however....I may be wrong about this.

~JH

[Dr Goggles]

I am null in bike rules but I thought the engine had to be originally used in a bike, making an ATV motor illegal....however....I may be wrong about this.
~JH

does the rule say "motorbike" or "motorcycle"? there would be the crack.....

The Colonel works( for only a little while longer) for an Aprilia dealer.... might have some ideas.... PM him on Grumm441

[John Burk]

How about a direct injection outboard engine .

[fredvance]

It has to be a motorcycle engine!!

[Anvil*]

The newer water-cooled engines start with a sizable advantage so your favorite flavor of small GP bike is a great starting point to look for an engine. That said, if you're budget is tight, one of the air-cooled Yamaha twins can be pressed into service and provide a very respectable ride (with reasonable parts availability).

[grumm441]

I  would use on one of the late model water cooled two stroke motorcycle engines
Some them make real good power reliably. and with any of the european ones you can get heaps of hot up parts as they still race 125
Don't use an outboard or quad motor. It would be a shame to set a record and then have it disputed beacuse the engine was never used in a bike when you probably could have similar power from a bike engine.

G

[Nortonist 592]

It has to be a motorcycle engine!!

One could argue the point that the Banshee is a motorcycle engine that is being used in a quad.  Man! I love this.  I feel like a roadster guy!

[bak189]

Is a "Westlake" a motorcycle engine?? Is a speedway bike a motorcycle?? No brakes, no headlight
no gearbox, no neutral, Ok....  OK you win ....it does have 2 wheels....so it must be legal in a 3 wheeler.
Love B.B.

[Nortonist 592]

Hey Bob, you forgot no right turn!!   If I may quote from the SCTA minutes of March 17, 1941.  "Vic Edlebrock attempted to define what is a roadster".  I they're still trying to work that out.    So don't worry about a Banshee engine!

[RichFox]

The Costella motorcycles went through this engine origin deal as his came from Go Karts but were built to be motorcycle engines and ATV with a few changes. But the parts affected had been replaced by aftermarket racing parts. So who was to say if it was a motorcycle engine or not?

[Glen LHeureux]

Jack Costella 5050 Honda CR250 S-G 53hp over 200mph @ SW.
Me 966 Honda RS250 A-G 92hp 148mph @ EM.

Just some numbers.

Singles are plentiful and simple to tune and simple to package.
Banshees are less plentiful and are a little bigger challenge.
MotoGP's make the most power, but there's a price to pay.

The correct answer, as usual, is proportionately linear to your power-to-budget ratio.

Write offline if you have any questions (jet at pistonsandrods dot com). I'll be glad to help where I can.

-The Other Glen
   SCTA 966B

[Dean Los Angeles]

The RS250 is a good choice for horsepower. I hear parts are hard to get and expensive.
The Yamaha TZ125 and TZ250 are built as race engines and are available and parts are somewhat reasonable. Both engines make huge amounts of power. The RZ and banshee engines were not built as race engines.

[RichFox]

i don't remember what brand of 125 it started out as but Jacks 'liner went 149.246 with 125cc on the dirt and 151.481 on the salt with Swede Tech power. Frontal area may have been the major factor