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Big Bore back to stock questions..

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Hey guys I have an 07 crf250r with an Athena 280 big bore kit and i'm thinking of going back to stock for more top end. I'm just wondering if any different year cylinders will work with my 07 and if they are any better or not? One other question.. I heard CP high compression pistons are good but I'm wondering what is the highest compression I can run without having to run race gas.

Thanks.

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Was 07 13.5 stock or 08? I would say no more than 14.0 If the cam is not super radical.

07 stock compression - 12.9:1

08 stock compression - 13.1:1

13.5:1 is really the highest you can go on 91 pump without needing race gas.

:thumbsup::thumbsup:

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oh and yes any 04-09 cylinder will fit but stay away from the 04 cause they have some known problems of the skirt breaking.

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I have the 08 cam on it. Do you know if there is any benefit for getting a different (newer) year cylinder? And If I did I would obviously have to get the same year piston from CP.

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Do you really think the 280 has less top end than stock?? It doesn't make sense unless the 280 piston is grossly overweight.

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