Changing Piston Compression Ratios

I was wondering what all needs to be done when changing compression ratios. I have an 05 CRF250R and it has the 12.5:1 piston in it now and i want to put something like a 12.8:1 or 12.9:1 in. What else should I do to accommodate the change or is just leaving it at 12.5:1 the smartest thing to do? I race competitively and want the extra power but don't want to have to worry about blowing the motor up. Any and all help would be much appreciated. 

Buying a High-Compression piston isn't bad for the engine at all, it just gives it more power and it makes it harder to kicked over tho because of the more compression but not that much harder. Go to weisco pistons website and select your year make and model bike and then look up piston kits then select a high compression piston. The only engine mod that would harm your bike would be a big bore kit, because big bore kits are just a new cylinder, and you can melt your heads on bore kits. But yeah, high compression pistons are a great way to increase power and won't hurt your engine at all.

Buying a High-Compression piston isn't bad for the engine at all, it just gives it more power and it makes it harder to kicked over tho because of the more compression but not that much harder. Go to weisco pistons website and select your year make and model bike and then look up piston kits then select a high compression piston. The only engine mod that would harm your bike would be a big bore kit, because big bore kits are just a new cylinder, and you can melt your heads on bore kits. But yeah, high compression pistons are a great way to increase power and won't hurt your engine at all.

Along with what I said above, when using a high compression piston it is also then required to run high octane fuel (premium 93 and higher) because of the compression increase for the combustion process.

Put in a 13.5:1 piston, it works fine will all stock parts, will add power from idle all the way to the rev limiter. And it is still 91 pump fuel safe.

 

The 04-09 crf250 motor is pretty much the same. And by the time 2009 hit the crf250 came stock with a 13.1:1 compression ratio.

 

13.5:1 is what you are looking for. If you have the money find a hot cams stage 2 cam, or a stock cam from a 2008-2009 crf250.  A 2008-2009 cdi box would also help. With the few simple parts you would have a much faster motor across the rpm range, and a much higher rev limiter.

Buying a High-Compression piston isn't bad for the engine at all, it just gives it more power and it makes it harder to kicked over tho because of the more compression but not that much harder. Go to weisco pistons website and select your year make and model bike and then look up piston kits then select a high compression piston. The only engine mod that would harm your bike would be a big bore kit, because big bore kits are just a new cylinder, and you can melt your heads on bore kits. But yeah, high compression pistons are a great way to increase power and won't hurt your engine at all.

I have ran big bore kits with higher than stock compression from 2005 to the present time and I have never melted a head or piston???

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