Quality parts from Mike Coe Show

Coe Show's 250 12.5 to 1 piston kit with pin, clips, and rings actually weighs less than a stock 230 piston, rings, pin and clips

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How to make an 16mm stroker crankshaft for a 02-05 CRF150f weigh less than ImageUploadedByThumper Talk1377466597.128780.jpgImageUploadedByThumper Talk1377466615.226649.jpgstock CRF 203f crankshaft?

How to make an 16mm stroker crankshaft for a 02-05 CRF150f weigh less than stock CRF 203f crankshaft?

OK, I don't understand the 16mm reference.  The rod ends/pins are 15mm standard.  You can't stroke a crank an additional 16mm??  66mm piston right?

Edited by Swiss

Sorry, a play on words. (Intentional attempt at humor)

Simply; a 230 crank in a 150 has (rounded off) 16 mm more stroke than a 150.

Basically, that is the main difference in the engine size of the two engines (as well as a couple of mm in the piston size)

So your pic is a 150 piston in a 230 barrel.

Close but it's a stock 230 piston in a cylinder modified to make a stock 223 cc 230 into a 247 cc.

A Larger sleeve and a larger piston is required to make a CRF 230 into a 250.

The catch is you must split the cases to bore the cases to fit the larger sleeve into them.

I'm doing all of this to an 05 CRF150f

So to make a 150 into a 250 you also need a 230 crankshaft as well as some Mike Coe Show kick start gears, or a complete 230 electric start system.

Stock kick start gears would just crumble.

Close but it's a stock 230 piston in a cylinder modified to make a stock 223 cc 230 into a 247 cc. A Larger sleeve and a larger piston is required to make a CRF 230 into a 250. The catch is you must split the cases to bore the cases to fit the larger sleeve into them. I'm doing all of this to an 05 CRF150fSo to make a 150 into a 250 you also need a 230 crankshaft as well as some Mike Coe Show kick start gears, or a complete 230 electric start system. Stock kick start gears would just crumble.[/

Ah, I hand bored my 230 cases without splitting the cases. Never again.

Nice build !

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