CRF 450 maintainance ?

Tom,

About the CRF 450
- Remember, this bike is sold as a "race ready" bike. No pro rider would think of running more than 1 event without tearing down to find out what's going on in there. That being said, here's what I've seen and heard about the 450:

Honda uses titanium intake valves against a hard alloy intake seat- not a good mix. When you pull the head off for the inevitable loss of compression due to intake valve face recession, have the machine shop install some nickel-bronze intake seats. Kibblewhite makes them, and your shop can get them. They should help strtch the time betwen top end part replacement. However, remember that titanium does have a finite life span...

(Other than that, the head (in my humble opinion) is a well executed piece.) I belive Honda has a suggested interval for "top end service". You might call the local dealer and find out what they suggest. That will give you an idea on cost vs. running time.

As far as routine maintainance on the head, check the adjustment early and often, it will give you an idea how things are wearing, and keep things from going south any faster than they should.

-Initial observations are showing fairly high rates of oil consumption. At least compared to what you might be used to. It may be that it's taking the rings a while to seat. However, no smoke and no fouled plugs. At any rate, initially you'll want to check the oil level after every couple of hours of hard riding. Desert riders take note...

The piston is a light weight (but not weak) small slipper skirt design that is obviously "a race piece"

-Tranny bolt/sight hole shouldn't be used to check oil level. It's too low. When you drain the oil fill it with the factory suggested amount. You'll be hating life otherwise, and so will your clutch.

Everyone I've talked to who has ridden one of these has raved about the instant torque and overall performance of this powerplant. Any time you squeeze a lot of performance from a given displacement you are going to make some longevity compromises. There are already new/stronger aftermarket components being made for this bike. Just like every other bike that's ever been made. There are a couple of things that might have been done differently, but we aren't privy to the entire thought process that goes on at Honda R&D. Their history has been pretty darn good in this area.

The good news is, when you feel like you are faster than the bike, you'll be able to put a combination with a big bore/ stroker kit, with more cam, a ported head and O/S valves, and put the spurs to that thing on the mile. Whew!
MP

Originally posted by mike perry
Tom,

The good news is, when you feel like you are faster than the bike, you'll be able to put a combination with a big bore/ stroker kit, with more cam, a ported head and O/S valves, and put the spurs to that thing on the mile. Whew!
MP

Click to expand...

Is this the Woody Kile approach?
Hey Mike! Thanks for all the help, you are the friggin man.
The 250f head is on the way.

Hello Mike! It is neat to see you post on this great site. I know I'm late returning info on the project XR300, but it is coming. I owe both you and SFO, your work and patience has been outstanding. Thanx

Regard's
Mark Ochs

Originally posted by mike perry
Tom,

About the CRF 450
Honda uses titanium intake valves against a hard alloy intake seat- not a good mix. When you pull the head off for the inevitable loss of compression due to intake valve face recession, have the machine shop install some nickel-bronze intake seats. Kibblewhite makes them, and your shop can get them. They should help strtch the time betwen top end part replacement. However, remember that titanium does have a finite life span...

(MP

Click to expand...

Hey Mike,
How is the honda ti head different than the yamaha?
Does the honda have harder seats than the yamaha?
Is the honda valve face errosion similiar to what the well used yamaha valve face errosion?
What about putting stainless valves in the honda instead of ti?
Thanks, Bill

The CRF does use a coating on the intake valve. It looks very much like one of the newer coatings I've seen on other titanium components. However, at this time I do not know that it is, and rather than speculate and have someone take it as "gospel" I'll wait until I have a definite answer.

Bill- The recession on the CRF intakes is very much like what we saw on your YZ pieces.

At this time we have not chemically seperated and compared the seat and valve materials from the 2 different models, and right now, I don't really see the need to. (That may change later)We know that the nickel bronze seat is an excellent material for use with the ti valve, and we will suggest that people who want to continue to use the ti valves convert to these seats.

As far as after-market valve materials, we will make a stainless valve in standard and 1.0mm O/S and offer the option of a custom made ti valve for those who want to continue to run that material.

The CRF spring kit will offer the experienced builder some latitude in applied force, so if he or she feels a need to make some additional increases based on cam profile, component material, and RPM he or she will be able to do so.
Regards,
Mike

Originally posted by mike perry
The CRF does use a coating on the intake valve. It looks very much like one of the newer coatings I've seen on other titanium components. However, at this time I do not know that it is, and rather than speculate and have someone take it as "gospel" I'll wait until I have a definite answer.

Bill- The recession on the CRF intakes is very much like what we saw on your YZ pieces.

At this time we have not chemically seperated and compared the seat and valve materials from the 2 different models, and right now, I don't really see the need to. (That may change later)We know that the nickel bronze seat is an excellent material for use with the ti valve, and we will suggest that people who want to continue to use the ti valves convert to these seats.

Click to expand...

I am just curious Mike as to why when you first saw the post baja valve face errosion you thought it was valve float caused and now it appears you are calling it soft valve~hard seat.
I don't intend to corner you I have just been running around saying VALVE FLOAT to every one who would listen and now it is a materials issue.
I defer to you and your viewpoints, just wondering... :think: :think:

Bill,

The valve spring pressure on the 2 bikes is substantially different. The result is the same. However, you raise a good point as to my initial observations about the Yamaha. I did not mention anything about seat materials. I do believe that the nickel bronze seat would be more forgiving on the ti valve in the Yamaha. And I would make that change if it were my bike. However, it too will beat the face up if the spring pressure is not enough to control valve motion.

Mike

mike, it is my pleasure to have a first name relationship with you.

inconel is very stable at high heat levels.
way past ti and ss.
check out spider man Mcbride or any of the fuel h-d's.

I build hot rod Harleys for a living and PM's valves are the best in the biz.Seen them last four seasons in a pro-stock bike.Tough with a capital T.The only valves I reccomend.So when are we gonna see some valves for the CRF???

they are already in some of the fastest cr-f's there are right now.
KMPI is the tuners little secret.
and they like being that way instead of being the white brothers of valves we have a real company that delivers the "trick" stuff, on time.

Tell me more..Ti?Stainless??Intake or exhaust?Both?I'd like to know more please.