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Has anyone tried BigBoreThumpers.com bolt on head?

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No but i just had my head redone by them and dang! the bolt on is a new thing for those guys. but the have been in the biz for over 30 years mostly in the street bike world. and they do awsome work.

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Not a bad deal for $575 if you don't want to deal with the downtime of having to get the seats re-cut and the new valves/springs installed.

I've already done a few valve jobs on CRFs and I could almost do them in my sleep, but being able to remove the old head and install a new one already set up would be tempting.

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Has anyone tried BigBoreThumpers.com bolt on head?

I have asked the same thing with no luck. Not sure if any one has went that route. I was wondering about the porting.

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I was wondering about the porting.

It's just a bowl blend job. It will help a little but it won't be something you can feel on the bike. You can save about $100 by assembling the head yourself. It only takes about ten minutes but there are details that are very important like spring and seal orientation.

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They do offer the 06 head, that's why it sounds interesting. Is the 06 head that much better than the 05?

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the 07 head is better because it has 30 mm exhaust valves instead of 31 mm valves

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It's just a bowl blend job. It will help a little but it won't be something you can feel on the bike. You can save about $100 by assembling the head yourself. It only takes about ten minutes but there are details that are very important like spring and seal orientation.

Yeah, I know it said the ports are matched to the valve seats. Did know if it would hurt performance or not. The simplicity of it is temping.lol

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07 and 08 heads in stock form are a good choice as a replacement head for all year models crf 450s .The smaller exhaust valve had really no efect in changing the performance the greater efect came from the reduced volume intake port.The 02-06 heads are still the heads to use for a performance build the 07 08 head can be ported to produce good flow and velocitys and is still caable of making a very powerfull crf.I had started selling complete new heads for all the crf models several years ago and continue to do so the difference is i was offering hi gh end steel valves and springs @ around $150 more than the previuos price mentioned a stock head with oem components could proball be purchased for around $530 .opening the throat area up to match the bowl usally ends up in a reduction of flow and velocity this area needs to be worked very carfully i have seen stock heads out perform ported heads because the id of the seat was opened to much .

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Not a bad deal for $575 if you don't want to deal with the downtime of having to get the seats re-cut and the new valves/springs installed.

I've already done a few valve jobs on CRFs and I could almost do them in my sleep, but being able to remove the old head and install a new one already set up would be tempting.

+1 The down time is killin me

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