Valve adjustment advise

[Guest]

I am currently in the process of going through my 1979 GS850 with 61,800 miles on it.

In checking the valve clearances I've found that I can get a .003 in. feeler gauge under #4 intake with a little extra play. On the other 7, I can't even get a .002 in(the thinnest I have) under the lobes. I can rotate the buckets on these which, from reading another post, means I DO have some clearance. My question is; should I 1) leave the shims that are currently in place or 2) replace the ones that are tight with the next thinner shim?
I am going to tear the motor down to replace all the seals/gaskets but I haven't done it yet. Wanted to figure where to go with the valve shims first.

Scott

[mike_of_bbg]

<.002" might still be in spec. The spec is 0.03mm-0.08mm - the lower end of which ends up being just above 0.001in. You'd probably be OK just to increase them all by one size (have you removed them and inventoried what sizes you have?). But the better route is to get one or two thin "reference" shims and take exact measurements with metric feeler gauges. You might even be able to take your thinnest shim and swap it into each position to measure - but be careful because you don't want to turn the cams past the buckets with no shim in there!

Find one of Steve's posts, pull up his profile and e-mail him for his spreadsheet.

[BassCliff]

Hi Mr. scotto58,

In inches the spec is .001" to .003".

In millimeters the spec is .03mm to .08mm. I would suggest picking up a metric feeler gauge set (they come in .01mm increments) so that you can make more resolute measurements.

Always re-measure after replacing a shim. Spin the motor a few times to seat the shim in the bucket, then measure. It's OK to run a little loose, but I would not recommend more than .02mm over (0.1mm max). Where possible, I run all of my clearances on the loose side of spec.

Just about everything you need to know about valve adjustments I've collected in a pictorial guide on my website. Please feel free to help yourself.


Thank you for your indulgence,

BassCliff

[Nessism]

I'd go smaller on the shims except for 4I. One size each may do it but you need to verify first, some of them may need two sizes.

[scotto58]

Thanks for the advise.

Mike: I haven't pulled the shims yet. That will be my next step. I do have a copy of Steve's spreadsheet.

BassCliff: I have a copy of your fine pictorial to follow. I'm going to try and find a good set of metric feeler gauges locally before I do anything else. As long as I'm in there I'd rather do it right the first time, even if it delays the start of my riding season a little more.

Nessism: I believe that is the route I'll end up taking. I will verify sizes first.

Scott