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2007 compression vs 2006


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I have both an 07 and a 05 CRF450. The 07 has a high compression piston in it (about 3hrs on it) and the 05 has the stocker. The 05 has always seemed like it has more compression when kicking it through slowly. I'm aware that the 07's went to a totaly different compression release mechanisim than the earlier models. Is this why the 07 has always been easier to kick through?

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Clearences are dead on. I did however have to replace one of the intake valves when I put the high compression piston in last summer. The valve was completely wore out, it had the clearences zeroed out and I couldnt get a small enough shim to get even 1 or 2 thousands clearence. I put a new valve in and it was easily shimmed to the correct lash. Perhaps my seats are trashed? But the bike starts first kick every time. Before i replaced the intake valve that was bad, i had to pump the throttle like 10 times before it would even try to start. Now I never have to touch the throttle. Just pull the choke, kick it once, and its running. The bike runs super hard to.

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05 Decompression arm is at .025

.006 on intake, .011 on exhaust

Motor is completely stock

07 Intake valves are .007 and .011,.010 on exhaust

I'm pretty sure the .007 is what the Hotcams III suggested

High compression piston, Hotcam III

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