CRF 450 Valve question

S

sandflyz

Member

Dec 10, 2004

71

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• Nov 28, 2006

• #1

I'm going to buy a left over 06 and i am wondering if i can replace the valves and springs with Kibblewhites before i even ride it. If i do this will i be able to swap in the new valve train without having to refinish the valve seats? Or should this be done regardless? Should i just ride it and wear out the stock valvetrain before changing over? Not sure what to do i've never owned a four stroke?

Thanks for the input

 

7

76GMC1500

Uhhh...

Oct 19, 2006

2,142

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• Nov 28, 2006

• #2

You have to lap the valve into the seat. All you need is some lapping compound and something to spin the valve with, usually a suction cup on the end of a stick.

 

Rich Rohrich

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• Nov 28, 2006

• #3

Production valve seats tend not to be concentric even on a new cylinder head. It's a big part of the reason that OEM titanium valves wear prematurely. If you are going to go to the expense of putting Kibblewhite parts it's in your best interest to have the valve seats cut to match the new valves and ensure the seats are concentric. You will also be sure that the seat is the appropriate width, and the seat center line has the correct relationship to the new valve. It's the only way you'll get long life out of the new valves.

Lapping won't help this situation.

 

7

76GMC1500

Uhhh...

Oct 19, 2006

2,142

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• Nov 28, 2006

• #4

Lapping will fix minor imperfections. When you do lap, it will show you the width of the contact area and whether or not it's concentric. I don't know if you can lap titanium valves because of special coatings and what not, but the stainless and inconel valves are ok to lap.

 

Rich Rohrich

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• Nov 28, 2006

• #5

76GMC1500 said:

Lapping will fix minor imperfections.

Click to expand...

It won't fix a seat that isn't concentric, and on a brand new head that tends to be a real issue. If the seat is too wide from the factory (also very common) lapping will only make it worse.

OEM titanium valves are coated and can't be lapped which is no great loss under the circumstances.

 

S

sp1tekiller

Member

Aug 23, 2004

74

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• Nov 29, 2006

• #6

Ride the bike until you wear out what's in there, no sense throwing away money. Sometimes you can get a lot of hours out of a set of valves.

 

7

76GMC1500

Uhhh...

Oct 19, 2006

2,142

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• Nov 29, 2006

• #7

But, if a valve or spring breaks, things get really expensive.

 

T

thorman75

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Dec 9, 1999

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• Nov 29, 2006

• #8

Do not go to the elves for advise for they will say both yes and no
-Gandalf

 

whenfoxforks-ruled

Old MX Racer

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Oct 19, 2006

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• Nov 29, 2006

• #9

Forwardmotion

Send it to Eric, niceeee!

 

Ol'89r

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• Dec 2, 2006

• #10

thorman75 said:

Do not go to the elves for advise for they will say both yes and no
-Gandalf

Click to expand...

That's because there are different ways of doing it, silly hobbit. ;)

You can do it the right way as Rich suggested. Since he does this for a living I would take his advice. :nod:

Or, you can save some money by running the bike with the stock valves until they start to recede in the head. Since it is a brand new bike, it will most likely go for a long time without needing anything. The stock springs, while not the best quality spring are suitable for use with the stock titanium valve.

IMO, if you want a bullet-proof system and money is not an issue. Install the Kibblewhite valves and spring set and have someone grind the seats.

 

SFO

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Feb 16, 2001

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• Dec 2, 2006

• #11

Ol'89r said:

"grind the seats."

Click to expand...

grinding a seat not be confused with lapping...