Bones25

Yes I was asking about a 68x68 because that is the closest to 500cc You cannot run a smaller engine in a larger class The target HP for the 500 class will go 170mph naked. I'm guessing 120hp. The record was set with a TZ750 with 250 cylinders= 500cc. Early 250's make about 60hp Thanks Sleeper I am only looking for infomation because changing the capacity by nearly 50% is outside what I have done. So from what you guys have said I will not attempt this with a banshee engine Cheers Bones

I have heard that a TZ 250 A -- 1990. The last reverse cylinder, parallel twin will make 90HP. @ 12k But I think these are Japanese HP. Probably measured at the crank-- no water pump-- no oil pump. I recon 80 would be more realistic Maybe make a little more with different pipes. They make more than the next model, a V twin, but are not as rideable. I think the last of the Aprillia 250 GP bikes were making 100hp. cheers Bones

Thanks every one.. It looks like there will be huge amount of development and then it may not make the required HP. I was trying not to do so much development to not get the reliability and power needed. I will go with the TZ250 which I have which I know. Again --- Thanks for your help Bones

Yes, 250 singles will go 10000 but they have been designed as a 250-- crank life would not be like a MXer. Remember a banshee engine was designed No point going smaller with a banshee. I have a TZ250 I can do that with. I have read they make 90hp-- I think Japanese ones :-) How often do you drag race guys need to replace the pistons and rings and cranks When the GP sidecars ran 2strokes at one stage they would put in cranks EVERY meeting. Practice on the last meeting's race cranks and fit new ones for the race. I would like to get a few meetings out of an engine. cheers Bones

Thanks Guys The reversed cylinder is not to make any more HP it is for packaging in the bike. The chassis has 4" ground clearance and the steering head is only 2'6''. Frontal area is everything in Land Speed I was thinking of a 68x68 engine but it looks like a 68 stroke will not go into Yamaha cases. Rules say motorcycle engine- not sure if the billet cases are legal or I want to spend that much. I can use ANY fuel I like- race gas-- gas class. Nitro,methanol-- fuel class. I will start with gas. Torque is very important. If the gearbox does not suite the power band the change into top gear may be useless. It will still have a road type gearbox and if the powerband is narrow the revs will drop too far and not pull. I'm chasing 170mph naked. I think the record was set on a TZ750 with 250 cylinders 10000rpm is a lot for a long stroke especially for 3 miles at full throttle. My experience is with early TZ's-- similar crank to banshees-- is that 10500 is enough for road racing. My mate logs his bike at Bonneville and it is WOT for over 1 minuite. Its a turbo GSXR 750--- 235mph Land Speed Racing is HARD on engines cheers Bones

Hi Guys I am a Land Speed racer and thinking of a new project. I would like to run in the 500 class with a 2stroke. So I think a Banshee/ RZ350 based engine would be a good option. I do all my own work-- fabricate frames, engines, pipes. I've messed around with TZ's on and off for a long time -- road racing and LSR I have found many combinations for bore and stroke to give close to 500cc but I like 68x68 . Have anyone had experience with this combination? Or something similar. What sort of HP can I expect with road racing port timing? Has anyone reversed the cylinders? I did this on a TZ350 (141mph, naked) and it worked very well and made the pipes much easier to make and package. Any help would be appreciated Bones25