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07 CRF450R valve clearance

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Ok, I could not be more new to riding dirt bikes, I recently thought I sholud check my vavle clearance, bike is running great, starts easy when cold maybe 3 kids, 1 kick everytime when warmed up, I just wanted to check. Anyways the intake right side was .005 and exuast were both .011 (good to go) but the left intake was real tight, .006 is spec +/-.001 and I could hardly get a .003 into it. What does this mean and should I do anything to fix it?

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should probably shim it before it gets hard to start.

So... take your valve clearance (.003 you said) and subtract what its supposed to be .006 so you get (negative) -.003 then add the size of the existing shim and that number is the number of the size shim you need.

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Again, new to riding, and maybe this should have been the first question, but won't the valve wear more towards the .006 than further towards .002?

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No, the valves themselves dont wear much if at all, its the valve seat that wears. So as the valve gets pounded into the seat the valve clearance will get tighter and tighter until it "zeros out" and there will be no clearance at all and the bike will not start.

p.s. where in az you live? im in tucson

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I am in Yuma, stones throw away from California border, the valve seat thing makes since, would you say that I am also loosing power the closer it gets to .000 and is it better to shim to .007, to the high end?

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No, the valves themselves dont wear much if at all, its the valve seat that wears. So as the valve gets pounded into the seat the valve clearance will get tighter and tighter until it "zeros out" and there will be no clearance at all and the bike will not start.

p.s. where in az you live? im in tucson

that is not 100% true.. it is the valve that wears way faster than the heads valve seat. Yes, the head's valve seat does wear, but the valve will wear till the edge of the valve is actually sharpened, no longer a multi sided valve face. The valve goes up into the seat, and the stem pushes on the valve shim closing the clearance between the bucket and the camshaft.

Yes, you may want to change your valve shim now to get it back to spec. If you "zero out" you have a harder time re-shimming.

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I am in Yuma, stones throw away from California border, the valve seat thing makes since, would you say that I am also loosing power the closer it gets to .000 and is it better to shim to .007, to the high end?

Nice, I love yuma, I usually ride glamis a few times a year.

Well, depends who you ask. Ive heard some people say that when its a bit tight the bike actually runs better and has more power until it zeros out n wont start but I dont know how true that is. I personally never notice a difference and I shim as soon as I see its getting tight because im always afraid of it getting too tight and a valve hitting the piston and blowing my top end (even though thats pretty rare for that to happen)

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that is not 100% true.. it is the valve that wears way faster than the heads valve seat. Yes, the head's valve seat does wear, but the valve will wear till the edge of the valve is actually sharpened, no longer a multi sided valve face. The valve goes up into the seat, and the stem pushes on the valve shim closing the clearance between the bucket and the camshaft.

Yes, you may want to change your valve shim now to get it back to spec. If you "zero out" you have a harder time re-shimming.

Hahaha duh, when I re-read what I typed I couldnt even believe I typed it lol. Ive rebuilt a few dozen heads and know how it goes, BRAIN FART lol. No more typing while running out the door, my bad

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your valves wear much faster than the seats. they get "cupped" the valves edge changes from

/ to | the valve face is actually pulled and extruded through the valve seat over time.

| - /

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Hahaha duh, when I re-read what I typed I couldnt even believe I typed it lol. Ive rebuilt a few dozen heads and know how it goes, BRAIN FART lol. No more typing while running out the door, my bad

no worries. thought that might have been the case .. :bonk:

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well thanks for the information, looks like i will be buying a shim kit and putting both left and right side intake back to .006. thanks again for all the help, any pointers when doing this would be appreciated.

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No, the valves themselves dont wear much if at all, its the valve seat that wears. So as the valve gets pounded into the seat the valve clearance will get tighter and tighter until it "zeros out" and there will be no clearance at all and the bike will not start.

p.s. where in az you live? im in tucson

Negative, its the valves...

that is not 100% true.. it is the valve that wears way faster than the heads valve seat. Yes, the head's valve seat does wear, but the valve will wear till the edge of the valve is actually sharpened, no longer a multi sided valve face. The valve goes up into the seat, and the stem pushes on the valve shim closing the clearance between the bucket and the camshaft.

Yes, you may want to change your valve shim now to get it back to spec. If you "zero out" you have a harder time re-shimming.

Yes ^^^^

Nice, I love yuma, I usually ride glamis a few times a year.

Well, depends who you ask. Ive heard some people say that when its a bit tight the bike actually runs better and has more power until it zeros out n wont start but I dont know how true that is. I personally never notice a difference and I shim as soon as I see its getting tight because im always afraid of it getting too tight and a valve hitting the piston and blowing my top end (even though thats pretty rare for that to happen)

This is true, but barely noticeable, when your valve specs are tighter the valve will open a little bit more, but .002 isnt much to notice really.

To the OP, if you go to You Tube and search "Honda CRF valve adjustment" there are several very good walkthrough videos to help you. Makes it almost idiotproof! Good luck and take your time, it isnt really that hard, the first time is the most difficult, after that you will be able to do a valve adjustment in about 30 minutes!

Also go and buy yourself a shim kit from hotcams so you have shims to adjust with, they cost about $80, but just one valve adjustment from a shop will be more than that so its a necessary investment IMO,

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well thanks for the information, looks like i will be buying a shim kit and putting both left and right side intake back to .006. thanks again for all the help, any pointers when doing this would be appreciated.

IF youve got time to wait...you can save some money

You probably dont need an entire kit. If you can wait, go figure out what shim you need and then just order the refill kit from TT for the HotCams reshim kit for quite a bit less money.

You want the 9.48mm shim diameter. Some smaller shops will "trade" you shims for a couple bucks too.

TT shows OEM shims at roughly 8 bucks a piece. Look at the thickness of all your shims before you go buy anything too. You may be able to swap one from one place to another, which is ok.

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at .003 i would re-shim. You can usually buy individual shims at a dealership or at a shop. every shop and dealer in my town sells individual shims. I buy single shims at my fav shop and they charge me $2 per shim so it costs me $8 to do a valve shim job. Most big dealerships will sell single shims also buy they are $5-6 each. still, $20 to make your bike in spec aint too shabby.

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