Race Kart questions

[dengieboy]

motor

Go careful running a two stroke that has been sat for a long time with out running. Two stroke rely on pressure the fuel/oil mix is drawn round the crankshaft here it lubes all the moving parts there will be two crankshaft seals on either side of the crankshaft these seal the crankcase from the outside air. Over time these seals will go hard if the motor is not used if you then go to start and run that motor it will run but the seals will not last long. And as they wear they let air in which then throws the fuel/oil air mix out which could lunch a piston if not noticed Another thing that will not help is if the motor had done a lot of hours (the seals do wear). Another thing to give some thought is that a two stroke has to be run on the correct mix of fuel and oil if this is not kept to you can trash it in seconds so do you know the history i would guess the answer is no so do you want to gamble that the motor is worn?. I would say if that was mine i would strip the motor down put a new set of crank seals in check the crank and big end bearing while i was there. I would then give the top end a check the small end bearings on two strokes can wear (again with lack of two stroke oil) they do suffer with carbon build up if cheap oil has been used this can happen behind the piston rings. Carbon build up on the cylinder head can cause hot spots which can pre ignite the mixture again which can lunch pistons.
I have worked on many many two stroke motorcycles any question you may have send me a message i will say nothing beats a two stroke i owned a 350 yamaha powervalve LC and the power band was like warp speed many many tricks can be used to get more out with out it going Bang!!!!........ Please don't kill it by not looking

 

[jbe24jg]

I'm well aware of how a two stroke works, I build vintage mopeds ranging from stock builds to variated bikes that rev well over 16k rpm. If I could find the parts to do an entire engine rebuild I would however the engine, a PCR, has next to no parts availability, especially this one, the tsv98 which is one of the later rotary valve induction models they made. I took all the proper precautions before starting, set the carb to factory specs, ran a slightly richer mix than the factory reccomended 16:1 rather that 20:1 so if there was an air leak from a bad seal the extra oil should prevent any possible bottom or top end damage. I also did compression tests before and after the first start, had a solid 175 before and after starting and warming it was a healthy 190 suggesting excellent top end health. Keep in mind I also only paid 100 bucks for the kart so I really had nothing to loose, I'd still make plenty of money selling just the frame alone. I took plenty of precautions and the results paid off.

 

[dengieboy]

motor

cool thank god some people that do not know how there engine works or what they should do i saw someone once use four stroke oil for two stroke it was quite a bang followed by a lot of smoke!!!

 

[jbe24jg]

jesus that must of been quite the sight. Yea it really is a shame people are starting to move away from 2 smokers. Honda discontinued all theirs. Yamaha, kawasaki and suzuki still make some, but they havent changed much since the mid 2000's. The only company that still actively develops 2 strokes is KTM, which is why i like them. I do also like yamaha though, since they still make their KT100 kart engine. I really wish more people knew about 2 strokes, their great fun, and not too bad to maintain. Great finding another 2 stroke guy in the forums!