CRF 450 Valves

I poked around and noticed they offer different cams for the CRF. Anybody played with any of these?

Ive been using the SS valves with good results Ive been tightening up the intake springs for a bit higher seat pressure . Like .020" You could use Shock valving shims under the lower spring seat if you like. Stainless valves are a bit heavier than stock Ti Never saw a float problem .

The Black Diamond Valves are more than "a little heavier". They are about 40% heavier. That is why we don't like to sell the valves without the spring kit. I'd rather not sell the valves than have a guy run them with the stock springs. It's not worth fifty bucks to us to have some poor guy scatter his engine.

Rich- What do you hear about the new "black box" for these things? How much higher does it move the limiter?

MP

Sorry to go off the CRF subject.But how good are these blackdiamond valves?Are they direct drop in fit?
Black Diamond List replacements for Husky 410 & 610 are these still available?

Originally posted by Taliesin
Sorry to go off the CRF subject.But how good are these blackdiamond valves?Are they direct drop in fit?
Black Diamond List replacements for Husky 410 & 610 are these still available?

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Yes.

Hi Mike : That would probably be a good way to sell the valves : Buy each valve with a spring. What do you think about YZF 400s which originally has steel valves Id like to switch to TI Exh valves and go with the 03 exh cam but am wondering if the 400s stock springs may be too much for the Ti valves and may pound the valves into the seats too hard. Any Ideas on this or should I just buy new 426 springs. Or maybe KW has a set .Its a relatively new 400 motor with very very little time on it if any. If it was really used up Id just buy new springs . I probably should anyway as theyre cheap. I havent yet checked the closed and compressed seat pressures but was wondering if any of you folks have. Any help would be greatly appreciated . Let us know . Thanks DEAN

In regards to the Yamaha spring question-

The problem of recessed valve faces is 2 fold. #1 seat material vs. ti valve material. #2 not enough spring pressure. As discussed at length previously, ti is soft and doesn't like to be run against a hard seat material. The recession problem is accelerated by insufficient spring pressure allowing the valve to bounce on that hard seat. Running a nickel bronze seat in the head will help, it won't be as brutal on the valve face, particularly in situations where the valve is bouncing on the seat. Adding some spring pressure will also help. Low pressure on a hard seat is a problem.

As near as I can tell there have been 3 generations of intake springs for the 400/426. I'll have to go back and check my notes to see which is which.

I know that some folks are running exhaust springs on everything (In the 5 valve Yamahas) because the exhaust spring has a slightly higher rate. But I don't know off the top of my head which year/model is the best way to go. But, SFO has spent a good deal of time researching the parts history on those heads and has built some. He probably has an answer for what to do until some new designs are available.

We are currently looking at (and have been for a while) all the smaller 5 valve Yamaha stuff. 250, 400, 426, and the 450. Also the R1 and FZR which are now being used in the SCCA "D" sports racer class.

The 5 valve cylinder head package is a challenge. We would like to make a dual spring for it, but, it must fit in a tight package,give a little more pressure than stock, and it has to live at those high rpms. SFO, Eric, and Rich will be among the first to know when we have something that we're satisfied with.
Regards-
Mike