It seems that when you order a new head for a 2002 to 2006 that its been superceded to the 07-08 head .in any case i now have a super cnc ported head for the 07-08 casting.
crf 450 head
Started by Ron Hamp, Feb 03 2012 05:11 PM
10 replies to this topic
Posted 03 February 2012 - 05:11 PM
It seems that when you order a new head for a 2002 to 2006 that its been superceded to the 07-08 head .in any case i now have a super cnc ported head for the 07-08 casting.
Posted 03 February 2012 - 05:19 PM
Ron Hamp, on 03 February 2012 - 05:11 PM, said:
It seems that when you order a new head for a 2002 to 2006 that its been superceded to the 07-08 head .in any case i now have a super cnc ported head for the 07-08 casting.
this is a PROBLEM for anyone still running 02-06 intake valves. they are 1mm wider and will NOT fit up into the valve pocket as far as they should, thus reducing the mating surface and if a mechanic isn't paying attention, will stick in HUGE shims to get spec clearances.
Posted 03 February 2012 - 07:05 PM
MELK-MAN, on 03 February 2012 - 05:19 PM, said:
this is a PROBLEM for anyone still running 02-06 intake valves. they are 1mm wider and will NOT fit up into the valve pocket as far as they should, thus reducing the mating surface and if a mechanic isn't paying attention, will stick in HUGE shims to get spec clearances.
Posted 03 February 2012 - 07:52 PM
mrmoto35, on 03 February 2012 - 07:05 PM, said:
I will remember this when it comes time to do mine. The local shops around here would have failed this test. I will be doing my own now minus the stuff that has to be done at a machine shop.
as long as ya order 07-08 intake valves with that new head, it won't be an issue. problem will be (if as Ron says) when you order say an 06 head and 06 valves.. and they send ya 07-08 head with 06 valves. I'm hoping they superced valves to 08 like they do the head.
Sorry to get this off track of Ron's cnc head post, but it's important.
Posted 04 February 2012 - 02:46 PM
the intake valves are the same the exhaust valves are 1 mm smaller on the 07-08 head and yes could cause some confusion and a big problem with valve to piston as the piston and exhaust valves are coming @ each other while the piston is actually chasing the intake valve when its closing this is why more valve to piston clearance is required on the exhaust valves .
Posted 04 February 2012 - 05:05 PM
Ron Hamp, on 04 February 2012 - 02:46 PM, said:
the intake valves are the same the exhaust valves are 1 mm smaller on the 07-08 head and yes could cause some confusion and a big problem with valve to piston as the piston and exhaust valves are coming @ each other while the piston is actually chasing the intake valve when its closing this is why more valve to piston clearance is required on the exhaust valves .
my bad.. knew it was one or the other just forgot it was the ex that were 1mm smaller than 02-06. good to get that cleared up.
Posted 05 February 2012 - 08:51 AM
MELK-MAN, on 03 February 2012 - 07:52 PM, said:
as long as ya order 07-08 intake valves with that new head, it won't be an issue. problem will be (if as Ron says) when you order say an 06 head and 06 valves.. and they send ya 07-08 head with 06 valves. I'm hoping they superced valves to 08 like they do the head.
Sorry to get this off track of Ron's cnc head post, but it's important.
Sorry to get this off track of Ron's cnc head post, but it's important.
Posted 05 February 2012 - 01:47 PM
Ron, how does the 07 08 head compare with the 02 06 head as far as tuning goes. Do the smaller exhaust valves restrict the potential of the head in any way? Which year head do you consider to be the best?
Posted 06 February 2012 - 02:42 PM
the smaller exhaust valves do not hurt the power theres a little less volume in the intake port giving the bike better response the 07-08 heads that i have done in the past have made 62 hp the most resent head flows the same as the efi heads i sell and have made 65 hp.
Posted 06 February 2012 - 07:07 PM
Ron Hamp, on 06 February 2012 - 02:42 PM, said:
the smaller exhaust valves do not hurt the power theres a little less volume in the intake port giving the bike better response the 07-08 heads that i have done in the past have made 62 hp the most resent head flows the same as the efi heads i sell and have made 65 hp.
