hotrods crank into 90 kx250

[GMRaceworx]

Okay I have a few questions on the 1990 kx250 engine I am hoping someone can advise on. The engine I have is going to get a complete overhaul and in the process tuned specifically for woods use.
I want to bore up this engine as big as possible/practical also.
First big question is that I would like to replace the tired old crank and rod with a hotrods crank. I see they advertise the 92' onwards cranks with 2mm longer stroke than the 90 model engine which would suit what I am doing, as long as the crank can be made to work without major headaches.
Second the cylinder I have has been resleeved. The cylinder was bored under 74mm to fit the sleeve, so I am wondering if this year cylinder can be bored and plated to 74mm and made to work with the power valves used in this year?
Any advise most welcome.

 

[kawraper]

I dont think ur gonna find a hotrods complete crank. My 93 125 I couldnt get anything but a factory crank for the big bucks. The 250s are a little easier to get parts for but I wish you the best of luck.

What is the stock bore on that bike? Id say ur best bet would be to bore the sleeve .020 over and throw a wiesco piston in it. If you can bore the sleve

There is some kind of science to boring/stroking to get the power usable and at the disired rpm. And im definetly no expert. Check out the eric gorr page might have some good info on that kind of stuff.

Even just rebuilding to stock and then using a fmf gnarly pipe, reeds and a flywheel weight might give you the disired outcome with out extensive internal mods........just a thought.

Unfortunatly the older bikes are getting hard to find internal engine parts for.....

 

[GMRaceworx]

hence my question about the fitment of a 92 crank. This option is the cheapest, best for tuning outcome desired, and strong. As long as there are no major dimension differences introduced into 92 model cranks. I am unfamiliar with these model engines. I can soon enough spec the crank I have and seek out comparative info on the replacement cranks but always safer and quicker to find someone who actually knows.

 

[TRexRacing]

Look here