81 GS650 Valve Shim Advice

[DaveP]

Just did a valve clearance check on my new to me 81 GS650. Here are my results:



I am planning to reuse one of the 2.60x shims on intake 2 to have that clearance a little less than 0.10mm.

What do you think about cylinder 3? I didn't see any 2.55x shims at Z1 Enterprises.

Any other comments on my adjustments?

Thanks,
Dave

[cowboyup3371]

Have you spoken with GhostGS1 yet to see if the Shim Club has any available? Look him up in the GS Services section of the forum.

[Sandro_916]

I'm having the same issue. Where do we find specific valve shims? Would it be worth it so get custom shims from a machine shop?

[Griffin]

I always use shims that get me in the .06 -.10 range. A little looser than .08 doesn't hurt anything. I'd leave them where they are listed on your chart and call it good.

Don't sweat a .01 or .02 difference. Your just want there to be enough clearance so that you don't have to worry about them for another 4,000 miles or so.

Don't forget to sync your carbs after you set clearances and button her all up. the carbs will probably need a bit of tweaking once the clearances change.

[Griffin]

I'm having the same issue. Where do we find specific valve shims? Would it be worth it so get custom shims from a machine shop?

No, it wouldn't. See my post above about clearances. They don't all have to be identical.

This guy sells shims for $7 each and always has an excellent selection in stock:

http://newmotorcycleparts.com/motor_parts/valve_shims.html

[Steve]

This guy sells shims for $7 each and always has an excellent selection in stock:

http://newmotorcycleparts.com/motor_...lve_shims.html

Z1 sells most of their shims for $4.82, but some are more expensive.

Wherever you shop for shims, make sure you get 29.5mm diameter.
Some Yamaha and Kawasaki shims are 29.0.

The only place you can order "X" shims is from the GSR Shim Club.

.

[tom203]

Be warned that some markings are in error- best to get an inexpensive micrometer and measure them, rather than assume.

[DaveP]

Thanks for the advice/comments. I will go with what I have in the chart and check the clearances again after installing the new shims.

Thanks,
Dave

[tkent02]

Be warned that some markings are in error- best to get an inexpensive micrometer and measure them, rather than assume.

Sometimes they wear a little thinner, sometimes they wear unevenly. Sometimes people put them in upside down and the numbers get worn off on the cam. It's really not all that critical, the only important thing is that the clearances are not too tight when all is done.

[Old guy]

Off topic, but anyone know the diameter of the bucket off hand, not just the shim? Nissan uses a lot of buckets/shims on their motors.

[tom203]

.. It's really not all that critical, the only important thing is that the clearances are not too tight when all is done.

I agree but when you take a shim out, you're best to measure it and not rely on number to decide what you need- I found about 30% of my shims marked incorrectly- a micrometer lets you know and offers a nice way to compare the ingoing shim to outgoing one.

[tom203]

Off topic, but anyone know the diameter of the bucket off hand, not just the shim? Nissan uses a lot of buckets/shims on their motors.

With vernier, it measures 33.5 mm diameter

[DaveP]

Just to close this out, here are my final numbers after the adjustments:


Initially I ordered 4 new shims form Z1 and rearranged 4 existing shims, but it turned out that Exhaust #1 and Intake #4 were tighter than the assumed 0.02mm since I could only measure 0.03mm and above. Both would still be in spec at 0.04mm, but at the opposite end of the desired clearance range than the other valves.

On Intake #4 I had a shim left over that improved the clearance to 0.09mm, but I had to order one more shim to improve the Exhaust #1 clearance to 0.09mm. Both ended up dropping two shim sizes while everything else dropped one shim size.

I like how the final numbers came out. All right around 0.08mm with a few at 0.10mm.

Dave