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jaggley

I checked my valve clearance yesterday!!

26 posts in this topic

I checked my valves yesterday for the first time. I got my bike last June and put 320 miles on it before the weather went bad, and my wife had our third duaghter. Over the winter I cleaned everything, installed fatbars, new twin air and oil filters, changed the oil(not the first time), greased the axles, tore apart and greased the swing arm, installed a trail tech computer, and installed new renthal dual layer grips.IMG_0337.jpg

Yesterday I finally got up the courage to tear into the motor and check the valves. I almost bought another XR when I read last year that this had to be done regularly. :p It was no big deal. It took me awhile to figure out where TDC was, the pictures in the manual did not explain it well.

My clearances were dead on. :) Now I can forget about it till next winter. :D It was so easy now I am thinking about that YZ cam. :)

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... I am thinking about that YZ cam. :)

I just happen to have a YZ450F camshaft on hand. PM me if your interested. :)

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congrates :) I cant understand why people go on about four strokes being too labour intensive and too complicated for the average punter as long as you follow the manual and take care you nearly always get it right.

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I just examined Math's engine internals and I was amazed to see so little wear on the engine. He has more than 10000km on it going from street do mx riding. He only noticed that the valve clearance was may be a bit tighter. Aside from that, everything looked great.

I read a few times in the past about the tightening of the valve clearance. Anyone have a theory about this ? I always tought it should loosen instead of the opposit.

Thanks for your infos :)

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the way these valves are set up...tightening is how they get out of spec...YOU DO NOT WANT THEM TO TIGHTEN UP. This is when you need to do your adjustment....they will not loosen. :)

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I have the YZ exhaust cam and love it, never go back!! Doesn't seem like alot more power just more response and more fun in the trails. Well worth it.

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I just finished checking the valve clearance on my wr. After near 6000 km the intake are .11 mm and the exhaust are .22 mm. I didn't check the valve when I first bought it. I should have done it. Because now I'm wondering about the rate of going out of spec. :)

There was no apparent wear on the head assembly. These engine are superbly well built :)

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There was no apparent wear on the head assembly. These engine are superbly well built :)

Absolutley the best fourstroke dirt bike engine in the world! :)

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I just examined Math's engine internals and I was amazed to see so little wear on the engine. He has more than 10000km on it going from street do mx riding. He only noticed that the valve clearance was may be a bit tighter. Aside from that, everything looked great.

I read a few times in the past about the tightening of the valve clearance. Anyone have a theory about this ? I always tought it should loosen instead of the opposit.

Thanks for your infos :)

I have a theory, probably wrong, but here it is anyway.

As the valve and housing wear, the valves retract further upward toward the cam, so the clearance between the cam and the valve/lifter/shim/thing becomes smaller.

Am I close?

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I have a theory, probably wrong, but here it is anyway.

As the valve and housing wear, the valves retract further upward toward the cam, so the clearance between the cam and the valve/lifter/shim/thing becomes smaller.

Am I close?

Its not a theory, but its fact! :) Valves will change the quickest when new as the angles between seat and valve face are differentr by 1 degree. Once the agles match (worn together) then it remains prety constant from there forward. Valve stems can also stretch, especially if you spinning it all real fast. A putter in the trails may never see thsi kind of wear. (that would be like me) Yes, tight is normal wear, loose means excess wear somewhere.

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Its not a theory, but its fact! :) Valves will change the quickest when new as the angles between seat and valve face are differentr by 1 degree. Once the agles match (worn together) then it remains prety constant from there forward. Valve stems can also stretch, especially if you spinning it all real fast. A putter in the trails may never see thsi kind of wear. (that would be like me) Yes, tight is normal wear, loose means excess wear somewhere.

Whoo-hoo!

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Yeah my valves happened to be tighter but then I'm not sure because I'm not that certain that I put the caps in their original position when I unmounted the head and rebuilt it... :) But I think they are thighter because they all seem tighter than the specs. So moving the caps from one position to the other won't help probably...

I'm happy to read that this is a sign of normal wear...

I'll be buying various size of shims so I can adjust it to perfection :)

This engine is sooooooo well built. A real dream!

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Toy mech is right, the same caps should go back in the same holes. But not the end of the world, it's just going to take a little longer to set the lash.

There really isn't a wear pattern between the two parts to worry about like a cam and a cam follower in a V-8. :)

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I'm tempted to think like Oasis...

Would somebody explain to me why it would be so important to put them back in their original place like the manual says.

If it is so important, does it mean you can't replace them with new ones?

All the caps are identical on my WR. They all have the same color spots on the inside (blue) and it matches with the color mark on the head. (like they explain they should in the manual)

So if the lash is in the spec at the end, then I suppose it's OK. :)

If I'm wrong, we'll discover it this spring cause I have no idea where each one was.

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Math, its because the caps are installed, torqued then the cam bore is machined. And yes, you can not buy a cam cap, it only comes with a new entire cylinder head! You can remove them and look for "fingerprints" ie hone marks to get them back in their original spot, cant even be flipped over either!. If they are in the wrong spot, you could end up with galling of the journal/camshaft which can destroy the head. In the automotive end, you can find a machine shop who could bore it to an oversize and add inserts (called bearings sometimes) but I doubt there is such a thing for motorcycles. Get them back where they belong. :)

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I recently adjusted all of my valves. Each valve was approximately half a thousandths too tight! I guess five thousand miles will do that to a motor... :):p

Yes, Indy already lectured me about it.... :)

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As hard as you ride David that is a testement to the Yamaha 450 motor! :p Best off road four stoke motor built! :)

I really lug my motor a lot and I still cant get more than 3,500 miles before getting tight. Intakes tighten quicker than the exhaust valves for me. :)

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