CRF Valve Seats

Smitty · Oct 21, 2002

Looking for the consensus from Mike Perry, Rich, SFO, Eric, etc, etc, etc…

I’ve decided to do the stainless valves and spring kit from Kibblewhite through Web Cams during the offseason, should I have the seats cleaned up? How should I determine this? Who can do the machining?

My CRF has around 120 hours on the stockers. I’m near the bottom of the shim range right now (1.55mm and 1.60mm. I believe the lowest are 1.2mm) and will be checking the tolerances weekly to avoid having them get down to zero again.

Are there any special tools required to do the valve replacement? I assume I need a valve spring compressor, are automotive types usable?

BTW, for the record I'm more than tired of reading posts bashing Honda for what I would consider a pretty expectable/predictable maintenance item when you consider the performance of these bikes. (Anyone ever notice that "competition use only" sticker, that means it's not a Buick to haul your family to Disneyland.)

marcusgunby · Oct 21, 2002

I havnt heard of one problem in the UK-i wonder if we can learn from it?different fuels??

Smitty · Oct 21, 2002

I'm sure that's a possiblity, I've heard some people discussing the effects of leaded race fuel, even lead substitutes. However, no one has presented an educated answer or test to prove they make a difference. Most of the wear is attributed to the inherent properties of titanium versus the allow seats. I guess you have to pick what will wear out and it was determined that the valves were more easily replaced............

biglou · Oct 21, 2002

Bill (SFO) gave me an educated lecture on it the other week over the phone, and the Kibblewhite stainless with a touch up to the seats was the way to go if I remember correctly. Of course, I can't remember exactly WHY that was the way to go. Hopefully it will wind up in print here shortly! :thumb:

Rich Rohrich · Oct 21, 2002

Originally posted by Smitty
I've heard some people discussing the effects of leaded race fuel, even lead substitutes.

Guys dumping CD2 and some of the other "lead substitute" products are kidding themselves. In talking to a number of people (Mike Perry and Eric included) none of us has seen any relationship between lead content (real or otherwise) and CRF valve wear.
I realize the lead cures all evils zealots will consider that a waste of ASCII but it seems like it needed to be said. :)

It's definitely worth having a competent machinst with the proper equipment cut the seats and blend the port throat. There's a bunch of airflow just waiting to be released and the long term relaibility of the SS valves will be improved by properly matching them to the seats.

At the risk of sounding like a schill I'd recommend having Kibblewhite do the valve machine work. They've done a few OS valve jobs for me and their work with the Serdi machine is art. Given the volume of work they do their turn-around time may be longer than some of the other places but the quality of the work is impeccable.

No special tools needed for the top-end. A standard import car sized valve compressor like they lend out at AutoZone will work fine. Eric's write up of the procedure along with the Honda service manual should cover you.

Have fun, it's a pretty cool engine to play around with.

Smitty · Oct 21, 2002

Originally posted by Rich Rohrich

Guys dumping CD2 and some of the other "lead substitute" products are kidding themselves. In talking to a number of people (Mike Perry and Eric included) none of us has seen any relationship between lead content (real or otherwise) and CRF valve wear.
I realize the lead cures all evils zealots will consider that a waste of ASCII but it seems like it needed to be said. :) ...............................
....Have fun, it's a pretty cool engine to play around with.

That's what I had gathered on the "lead" somehow I deduced that had the bike required lead (or Marvel Mystery Oil or Bailey's Irish Creme or Pigs Blood) Honda may have mentioned that somewhere.

It's definitely a cool engine! It's real easy to work on also. Nothing gave me fits and I have skin on my knuckles. I am curious if any of the other MX 4 strokes use anything besides the bucket and shim? Is the shim just so much simpler, accurate, reliable, and lighter than any type of screw adjustment?

When I talked to Kibblewhite it sounded like they did not sell direct to the public? Was I mistaken? I don't mind a two week turn around but anything over that could be a problem. Second options? (PM Me if easier)

:thumb:

Rich Rohrich · Oct 21, 2002

Originally posted by Smitty

That's what I had gathered on the "lead" somehow I deduced that had the bike required lead (or Marvel Mystery Oil or Bailey's Irish Creme or Pigs Blood) Honda may have mentioned that somewhere.

Wise thinking :thumb:

Originally posted by Smitty
Is the shim just so much simpler, accurate, reliable, and lighter than any type of screw adjustment?

I don't know that it's necessarily lighter using buckets but they are well understood, reliable, cheap, and make for fairly small cyclinder heads. So even though there may be superior designs (F1 uses finger followers) on the whole buckets are tough to beat in a cost sensitive design.

Originally posted by Smitty

When I talked to Kibblewhite it sounded like they did not sell direct to the public? Was I mistaken?

That may be true, I'm not sure.
Bill (SFO) will know. I'll ask him to follow up.

SFO · Oct 22, 2002

KMPI is a manufacturer first.
Due to the overwhellming response for the cr-f kit KMPI is selling it through their distributors, most notably web-cam.

http://www.webcaminc.net/

They (KMPI) are really not staffed or designed to support retail sales or machine work. Mike Perry is pretty much a one man band there (in the shop) and can't cover all the trade shows, head work, and technical calls that would be part of retail.

I hope I am explaining this well enough.
I am sure Eric could handle the conversion and requisite machine work, or another of my favorites is an old friend of Old 89'R, Mike Crowther at Engine Dynamics.

http://www.enginedynamics.com/

There is really no proven cause and effect for the cr-f valve train issues as of yet, it all appears to be hyperbole. Some do it some don't.

I would double check the stem diameters of the SS replacements as you might have to resize your guides for the proper stem to guide bore clearance.

Hopefully Mike Perry will pop up and straighten this all out....

Rich Rohrich · Oct 22, 2002

Originally posted by SFO
They (KMPI) are really not staffed or designed to support retail sales or machine work.

Thanks for clearing that up Bill. :thumb:

Any news from Mira. ;)

MxKid512 · Oct 22, 2002

I heard that the 03's have different part numbers for the cylinder heads. Could this mean Honda has changed something in the new bikes? Has anyone had an 03 apart to confirm this? Just asking because if something has changed in relation to the problem, it would be interesting to see what Honda thought was causing the valves to wear away. :think:

Offroadr · Oct 22, 2002

Originally posted by Rich Rohrich
Any news from Mira. ;)

Yea from what I have been reading those Mira machines are the $hit :p

SFO · Oct 22, 2002

Originally posted by Offroadr

Yea from what I have been reading those Mira machines are the $hit :p

Shoot, do I have a story for you...
Blast me an email
bill@mossmachine.com

What have you heard, BTW?
Ant published reports?
Do you know who has one?
I saw them in PRI magazine and am waiting for data...

truespode · Oct 23, 2002

Originally posted by MxKid512
I heard that the 03's have different part numbers for the cylinder heads. Could this mean Honda has changed something in the new bikes?

Is this true?

Ivan

CRF Valve Seats

Smitty

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