Jump to content
Sign in to follow this  

what parts are needed for new head?

Recommended Posts

I've got an 07 CRF450R and the head is not in the greatest of shape. the seats are wore and and are eating the valves up. Basically what I want to do is buy a new head. I'm looking at a 04-06 head, due to the larger exhaust valves than the 07-08 models. (I run hillclimbs so I dont want the smooth power of the 07-08 heads, I need explosive power and lots of it...that will come with the porting the head will recieve after purchasing it).

What I'm needing to know is what all is involved in setting up a new head? I know I'm gonna need to buy the valves, springs, and seals, but will the other parts such as the keepers, retainers, and valve spring seats work out of my 07 head?

Also, when instaling the valves do the valves need to be lapped or can you just throw the valves in the head and run em?...how do you seat the valve to the valve seat?

Share this post


Link to post
Share on other sites

Go to crfsonly.com They have a great store and will do all the work for you, so all you will need to do is bolt the head on and go.

Share this post


Link to post
Share on other sites

I dont mind doing the work myself. I do mind paying someone else $60hr to do the work I'm capable of doing. I've looked at the CRFonly deal, and I think I can get it done cheaper by doing it myself. I think they are wanting like $600 for the complete deal.

I've seen that Pro X is now offering a steel valve kit that comes with 2 valves, and 2 springs for less than $100. If I can use all my old hardware off the 07 head, I'll only be into the new head for around $450.

Share this post


Link to post
Share on other sites

The power differnece between the old heads 02 to 06 and the new head 07-08 aren't great and if anything the new head has a higher peak number,and for your application ie. hillclimbing the new head would be better.The reason I say better is this, when you have to let off the throttle say just a little the new head will still pull strong when the throttle is reapplied, with the old head you probably have to down shift. And as far as explosive power that is just a myth from someone that has never A-B'd these heads back to back.The difference in power feel is very minimal.

If it was my head I would find someone that could do a proper valve job on one of these even if I had to ship it elsewhere. You will for sure need all new valves intake and exhaust as well as new exhaust guides and seals for all,get new springs too as the do fatigue.cheers

Share this post


Link to post
Share on other sites

Well, the hills I ride are pretty much wide open hills. no letting off the throttle at all, the jumps are stacked to where you jump more out than up never letting off the throttle speeds at around 45-50mph and the farther up the hill the faster you go. The best way to describe it would be an up hill drag race. The more top end the better. Most of the really fast bikes usually have oversized valves installed in the intake and exhaust.

It seems to almost be cheaper to buy a new head for $250 than it is to have an old head redone

Share this post


Link to post
Share on other sites

The '06 head will make more peak power with the right porting and cam, if that's what you are after. Use the '06 because it's got improved intake valve seats. I wouldn't re-use any of the old parts, especially the exhaust manifold studs. I would sell the old head assembly on ebay and get about $100, which will cover the additional hardware and then some.

Share this post


Link to post
Share on other sites

i ride an 06 crf450r i just recently did my top end i asked and asked about the seats and if they had to be lapped in. and i got yes answers and no's. i went with no. what i did was put the new ones in turned the head upside down and pored gas on the bottom of the valves if it runs quickly through there not seated good if it takes a minute there fine. mine where okay and my bike is runnin great.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...