Need Advice

[JDaniel]

Adjusting my valves. Intakes all measure 0.004 The 0.005 feeler gauge will not fit. Should I leave them alone or try to get closer to 0.006

[bongobobny]

IMHO leave them be as the cleasrance should open with age but others might give another opinion. Unless the bike is hard starting you probably don't need to adjust the valves...

[Freebird]

I may be wrong but I THINK the valves get tiger with age. As the shims wear, the valves get tighter. If I am correct in that, then I would recommend adjusting them a bit.

[Flyinfool]

You are close Don.

They do get tighter with age.

But it is not from shim or cam wear, that would open them up more.

The reason they get tighter is that the valve to head surfaces wear causing the valve to seat deeper into the head. As this surface wears you can get to the point of zero clearance where the valve will no longer close completely. This can burn up the valve.

 

So bigger clearance is better.

[bongobobny]

Jeff is right! I stand corrected...

[djh3]

Yup as a general rule for the valves error on the bigger clearence side. A fellow once put it to me as the valve springs are trying to pull the valve thru the head so if the clearence on the shim/cam is small it will not close eventually.

[wes0778]

You are close Don.

They do get tighter with age.

But it is not from shim or cam wear, that would open them up more.

The reason they get tighter is that the valve to head surfaces wear causing the valve to seat deeper into the head. As this surface wears you can get to the point of zero clearance where the valve will no longer close completely. This can burn up the valve.

 

So bigger clearance is better.

 

But too big and the cam "slaps" the shim instead of meeting it with the ramp up and it "slams" the valve against the seat, as it closes, as opposed to letting it close gently as it comes down the ramp on the cam lobe.

[djh3]

OK so within reason. If the spec is .004 to .007 Aim for the higher end of spec. I had a couple that were at the minmums. I had some spare shims, although within the limits I figured it was better to adjust them now and not have to worry about being out of spec before next adjustment time.