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CRF450 Head Question

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Hi All,

 

I'm getting ready to rebuild the engine on my 2005 CRF450R, and I will be buying a new complete head from Big Bore Thumpers. I'm hoping to get some feedback regarding switching to the 2008 head they sell (with the smaller valves). Would switching to this head provide an advantage over my 2005 head? I love the way the bike runs now, so my inclination is to stick with the stock head, but if there is good reason to change over to the newer head, I'd like to know since I'm going to replace it anyway. Any feedback with regard to this change or the results it is likely to produce would be greatly appreciated. Thanks,

 

Ian

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I put an 08 head on my 04 with ss valves. Runs fine. 1mm smaller exst valves are supposed to give a bit better low/mid. I don't think most of us would be able to tell but if you do switch, i would engrave on the side it's an 08 head. This way if you sell the bike, the next owner won't mistakenly order the 05 valves. they will fit, but you will end up with MASSIVE shims and some won't know why and run the bike anyway, as the valve won't go into the head as far as it should..

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I agree with koolaid. If anything I'd get that one ported. 08 head has smaller valves for a SMOOTHER power delivery to not wear you out as quick. If I was JUST racing motocross I'd consider that but I'm not and I prefer raw power. That's just me tho

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Stick with the original 05 head... if the bike runs great with the current head, don't mess with it.

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Good advice from all the members.  Stick with the 05 head as you won't notice much of a difference.   Had an 05 model & an 06 with the 08 head & couldn't feel much of a difference between them.  

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the 08 head is better because the intake is designed different, also add a 41mm carb and have it ported and polished. i talked to several different porters and everyone told me the 08 head was a better head, the valve pockets are smaller in the new style head

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the 08 head is better because the intake is designed different, also add a 41mm carb and have it ported and polished. i talked to several different porters and everyone told me the 08 head was a better head, the valve pockets are smaller in the new style head

...when matched to the '08 CDI, carb, and pipe.

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yeah it probably would be better to match the cdi and pipe also. but even if it i not matched i believe the valve seats are better material than the old heads, i have never had a issue with my seats and i have ti valves, stock seats

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I installed a fast heads 08 head with upgraded ti valves and springs on my 06. Added 13.5 comp piston. Dialed in the air screw. Love it. Test rode a 14 yz450f and was happy to get back on my old junk. 30 trouble free hours on it with one kick starts

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