Quote:
Originally Posted by gasser
The 250 and 300 have the same stroke and there is no difference in the bottom end components. The 200 shares most of the parts with the bigger bikes but not all. A 250 can easily be made into a 300 by just replacing the top end (I've got an 01xc300 top end on my 07ec250).
There was talk in one of the forums about a "275" gasser. If I remember right it was one or more bikes modified by the French TEAM for racing in the ISDE.
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Good Day everyone!
You were quite correct in your 250-300 statement above.
Re: the "275" gasser.
We made several 274cc Gassers out of 250cc bikes. We would take a cylinder slated for repair, and send it, the head, and a 14th oversize Wiseco piston built for the TRX250R Honda quadracer to the cylinder repair business.
They would bore the cylinder to work with the oversized piston, and then coat the cylinder bore with their version of "nikasil" and hone the cylinder to match the piston for proper clearance.
They would build up and then machine down the head to match the new bore.
The piston kit we used was the Wiseco 526M06950. You can tell by the designation that it has a 69.5mm diameter, instead of the normal GG 250 size of 66.40 (minus a few hundreths) Wiseco kit #849M06640 Roughly 3.1 mm larger in diameter.
One more thing... the exhaust valve "flapper" had to be trimmed a bit to keep it away from the larger piston.
We also did this to several Honda CR250R bikes.
Good Riding!
Jim