valve inspection question

[WIRE-DOC]

I am checking my valves on my 07yz 450. I lined up the intake and exhaust cam with the cylinder head surface, but in the sight window on the crankcase cover it does not line up exactly one the line. There are 3 lines in the crankcase sight window and I am just passed the third one from left to right. Is it more important to line up the cams with the head or line up the lines in the crankshaft window? HELP! Thanks

[desert-rat660]

the cams lobe position is most important

[grayracer513]

Except for the fact that there are two TDC's in the Otto cycle, and both sets of valves are open on the wrong one, there's not much difference. The crank position is the more pertinent, however, especially in matters of timing. Line up the TDC mark (the one farthest to the right, or clockwise, looking at the flywheel), then check. The cam timing marks will rarely line up exactly, and for the purpose of checking valve clearances, 10 degrees either way won't change much.

[WIRE-DOC]

Thanks for the help.

[grayracer513]

I actually don't often open the timing plug when checking clearance. Just eyeballing the cams into position is fine, really. In fact, you can check the exhausts just short of TDC, and the intakes just past it, and be perfectly OK.

[swaldrop]

I actually don't often open the timing plug when checking clearance. Just eyeballing the cams into position is fine, really. In fact, you can check the exhausts just short of TDC, and the intakes just past it, and be perfectly OK.

Good info. While we're on the subject...

A couple months ago I rebuilt my top end after I dropped a valve. Everything went pretty smooth but now my intake valves are reading a bit high. I thought for sure that they were all right at .15mm when I got done (I even checked them again after the first ride), but now a couple are sitting at about .18mm.

If they did in fact fall out of adjustment, what would cause the clearance to increase? I just ordered a shim kit and will re-shim when I get it, but is that gap too much to risk riding until then?

My initial thoughts are that I may not have adjusted them properly in the first place although everything seemed fine at the time.

So is it better to have the valves clearances on the tight side or the loose side? What causes a valve to get loose/tight?

Sorry to jack the thread, but the title was too perfect to start another...

[WIRE-DOC]

I just finished checking my valve clearance. All good exept 1 intake .10-.15 is within range and I can fit a .20 into one of the intake lobes. This bike is an 07 with 10hours. ***? Why would only one be out of specs?

[grayracer513]

Riding it once or twice with it at .18mm should be OK. That's barely over .001".

The change was probably caused by not having the shims completely seated on the first check. You should strive to set the valve at the lower limit of clearance, alyjough the specified range is only .002" wide, so it's not truly critical.

[desert-rat660]

could of had some debris in between the shim and bucket that worked theyre way out after riding, just a thought

[bigred455]

Straight from the factory not even started by me, left intake on my 07 was .003in .I shimmed it and it hasn't budged or the others,DEAD ON.They are not perfect when leaving the factory.

[WIRE-DOC]

Should I just change the one shim and not even touch the other two? The others had a slight drag at .15

[desert-rat660]

i wouldnt worry about it, the cleareance will slowly decrease as the valvetrain wears

[swaldrop]

i wouldnt worry about it, the cleareance will slowly decrease as the valvetrain wears

So the tighter it gets, the more wear? That makes sense but I wanted to make sure...

[desert-rat660]

overtime the valves start to "tulip" they get pounded into the valve seats more causing the valve stem to get closer to the cam, decreasing the clearance between the valve bucket and cam shaft, u will have to reshim the head once the tolerance becomes too tight

[bigred455]

If the 0ne intake is .20mm that is a little over .007in. I would definetly shim WIREDOC.

[grayracer513]

Should I just change the one shim and not even touch the other two? The others had a slight drag at .15

If the other two are .15, they are within specification, and don't need a correction The other one is out, and must be shimmed.

So the tighter it gets, the more wear? That makes sense but I wanted to make sure...

It's the other way 'round; the more wear at the valve face and seat, the tighter they get.

However, other than some initial settling of parts, there should be little or no movement in the clearances for a very long time. Ti valves have an extremely thin hard coat on them, and pretty much any measurable wear at the face of the valve renders them unusable. Again, not counting early settling, or assembly errors, any YZF with Ti valves that needs a full .05mm smaller shim needs to be reinspected at short intervals. If it ever needs one .10mm smaller than the original, it needs a valve.

[BlackT5]

Do they offer .025mm shims? If the range is only .05 the you would be either on the verge tight or loose. Mine brand new were on the tight side from the factory and if I went down a size they would be loose.

[grayracer513]

Honda does list shims in .025mm increments, and they will fit the YZF, but when the spec says .10-.15, that means that both .10 and .15 are acceptable. The factory always builds to the tight side, and they use shims in .01mm increments to set the valves as near .10-.11 and .20-.21mm as they can get them.

[swaldrop]

It's the other way 'round; the more wear at the valve face and seat, the tighter they get.

Yeah, that's what I meant. I just wanted to make sure that the 'loosening' of the valves wasn't due to a valve or valve seat being worn. I am going to shim them up and try to get them on the tight side this time.

I actually had the same problem with the shims being in .05 increments. I had to choose the tight or loose side of the adjustment and it looks like I chose the wrong side.

Oh well. It's good practice... Thanks again for all the help.

Steve

[WIRE-DOC]

Just finished installing new shims. I installed a 185 and it is still out of spec. 175 is stock. I went up .10 and I can still fit a .20 in it with minimal drag. I even took everything apart and did it twice just to make sure that no dirt was around the bucket. What gives? Should I install a .190 or could there be a problem elsewhere?