Setting the Valves

[BowlingSS]

On a 1980 XS1100 SG does everyone use the standard manual valve clearances? My manual has .004 to .006 on the intake and 8 to 10 on the exhaust. All my exhaust need changing after doing a valve job. Does ever one use the lower spec (.006)? I have one intake that I can not even get a .0015 under. Three intakes are at .0045 to .005.

That Yamaha tool is a pain to use. I have the write up but it does not want to catch the lip of the cup after I turn the cam off the lobe. I might just take the cams out.

Thanks.
Bill

[DiverRay]

You need to use the UPPER LIMIT, 0.006, if you just installed or refreshed the valves! The valve clearance tightens up with time, and it happens faster on "new" installs or a fresh engine.
If you need to replace all the shims on the exhaust, yes, remove the cam. It will make the job much easier.

[bikerphil]

The exhaust valves have a wider gap because they get hotter (expand more) than the intake side. I would not use the lower intake valve clearances on the exhaust valves if that is what you are asking.

[crazy steve]

There's pluses and minuses for using the upper and lower clearances. Now, keep in mind that once clearances go below the recommended minimums, you can start having tuning/running issues. Particularly on the exhaust valves, as that can accelerate wear on the valves/seat.

Running less clearance or 'tight': Pluses, maximum valve lift/duration for performance, less noise. Minus, more frequent valve adjustments.

Running more clearance or 'loose': Plus, less frequent valve adjustments. Minuses, more noise.

Specs: Exhaust, .008-.010" all years. Intake, .006-.008" '78-79, .004-.006" '80-82.

Many owners (myself included) prefer 'loose'. Adjusting the valves can be a PITA, and this lets you do it less often. And many run the 'early' '78-79 specs, which is the same for the exhaust but .002" looser yet on the intakes; Yamaha reduced the spec to cut down on valvetrain noise on the later bikes. In terms of performance, either spec will give pretty much the same power on the street; unless you're racing and looking for every last .001 of a second, you'll never know the difference. IMO it's more important that the valves be adjusted so all have the same clearance (within .001" +/-) as this promotes smoother running. Given the choice, if I had 3 valves that came in at a 'loose' .009" but not quite .010" and one at barely .008", I'd bump the tight valve up one shim and run it a bit over .010". As long as you don't go more .001" above the upper limit, it will 'wear in' and be fine. Each shim size change will change clearance by .002" (smaller shim more clearance, bigger less).

On every motor that I've ran into with poor compression numbers, they all improved (sometimes drastically) with a proper valve adjustment.

[BowlingSS]

Thanks everyone. Should I change the intakes that are .0045? I am going to take both cams out to change the shims.

Bill

[TADracer]

I do not disagree with what anyone above has stated. But call me different, I shoot for the middle of the range.

Having said that, if you are adjusting after a new valve job then go to the higher end of the tolerance because your valves will wear in fast at first closing the gap. I have found that after running awhile the valve seats seem to work harden on the surface because they are in a good heat range and are constantly getting hammered. But, even just lap your valves lightly and you are removing this work hardening layer and a fast wear-in will happen again. So, after lapping valves (which I try not to do unless really, really needed), go looser and let them wear to the middle of the range and then maintain that with regular valve checks/adjustments.

[Radioguylogs]

The available increments of shims usually give you only one choice that is within spec.

If I have one that straddles the spec, I choose to make it loose so it doesn't wear out of spec.

[motoman]

That Yamaha tool is a pain to use. I have the write up but it does not want to catch the lip of the cup after I turn the cam off the lobe. I might just take the cams out.

That it is........just as well box it and I'll PM you my mailing addy.......paying your postage cost/time/ fuel is NOT an issue....even in advance.

[jetmechmarty]

I pulled the cams last year, but I had a lot of shims and a chain and tensioner to replace. Last time, I used the MP tool. Piece of cake! I'll do it that way from now on. I'm a klutz and I made it work.