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(Date Posted:06/02/2008 4:55 PM)
G'day, I'm from down under in New Zealand and I race a honda CB250RS which is the same motor as the XL250 I believe. It's the lateish model engine with the twin port heads. It goes quite well at the moment, running mid to from pack and beating a lot of bigger bikes like 500 brit's and 500 ducattis and stuff like that, but I want it to be a bit more up the front. The motor is standard except from no airbox, and a two into one exhaust which consists of two pipes going down to a collector then going into foot long hotdog muffler under the motor with a wee pipe sticking out the right side. What can I do to make this motor really sing? More capacity? Cams? Porting work? Compression? The ring gap is slightly over specification but it doesn't seem to effect it, as it's just as fast if not slightly faster than all of the other CB250RS's out there. The gearbox jumps out of first every time when taking off too and sometimes out of 4th into a false neutral or 3rd which gets pretty interesting when you are up in the redline doing about 10500 RPM!!!!! What could cause that? Worn selectors? I have another shitty looking bottom end hwere which I had to get the generator out of when my one packed up. Maybe I should just nick the gearbox out of that? What do I need to look for to make sure this gearbox isn't doing it too? How about those balance shafts? I know you need them as the engine vibrated VERY badly without them, or can I just take them out then re-balance the crank to suit? Cheers, Sam
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