How critical is lobe position when checking valve clearances?

[sacruickshank]

UPDATE - Thanks all for the guidance. I've now re-checked all the clearances using the pair technique and lobe positions described. Five are within spec, but three (1E, 3I, 4I) are <0.02mm. The buckets still spin freely, so at least they are not touching which should be good enough for a few test short starts. I'll re-check & adjust once Spring and test rides gets nearer.

[salty_monk]

You'd want to get those shims swapped out fairly quickly though, loss of compression, burnt valves etc

[red1100]

A degree wheel and dial indicator will get you spot on at every lobe. Not that hard to use.

[Nessism]

A degree wheel and dial indicator will get you spot on at every lobe. Not that hard to use.

And what would spot on be?

[red1100]

Spot on is finding exact tdc of cyl 1 with a degree wheel and dial indicator. It's the only way to know the piston is truly at the top. It is a little involved but dead nuts accurate.Make a wire pointer that points to the edge of your degree wheel. Screw in a positive stop bolt in the spark plug hole,bring the crank around by hand till it touches the stop,Mark down the number the pointer hits on the degree wheel. Now turn the crank the other direction slowly all the way around till the piston stops again,read the number.In the simplest terms if the degree wheel sez 20 going one way and 10 going the other TDC is at 15. Whatever the wheel reads it will be halfway between the two as noted on the degree wheel.

[Nessism]

Spot on is finding exact tdc of cyl 1 with a degree wheel and dial indicator. It's the only way to know the piston is truly at the top. It is a little involved but dead nuts accurate.Make a wire pointer that points to the edge of your degree wheel. Screw in a positive stop bolt in the spark plug hole,bring the crank around by hand till it touches the stop,Mark down the number the pointer hits on the degree wheel. Now turn the crank the other direction slowly all the way around till the piston stops again,read the number.In the simplest terms if the degree wheel sez 20 going one way and 10 going the other TDC is at 15. Whatever the wheel reads it will be halfway between the two as noted on the degree wheel.

Sorry, but I don't understand why you are wanting to put the cylinder at TDC? Does that correspond to the Suzuki cam positions described in the factory service manual? The valves are not supposed to be adjusted individually, they are to be adjusted in pairs for the reason previously described.

[Steve]

Spot on is finding exact tdc of cyl 1 with a degree wheel and dial indicator. It's the only way to know the piston is truly at the top.

Very true, but TDC is not where you want to be.

Someday I might bother to see what the angle might be, but you need to have the two adjacent cam lobes approximately equal-distance from the axis of their respective valves. Then measure the clearance on BOTH valves.

There is a bit of leeway in both directions, so the exact degree is not critical, just eyeball an approximate 'equal' and you will be good.

.

[sacruickshank]

You'd want to get those shims swapped out fairly quickly though, loss of compression, burnt valves etc

That's part of the plan for the next few weeks.