1981 XS850

[ekestle]

Just picked up a 1981 XS850. Runs fine but when it gets warm the idle will go up 3k rpm.
I am changing the cracked intake boots but also want to adjust the valves. Getting conflicting
info on what the intake and exhaust valves should be set at. Any help with the rpm problem
or valve setting would be appreciated!

 

[motormike]

Can't recall the " book ".... but I set mine at two on intakes and 4 on exhaust.. works fer me. Think the book is looser

 

[azman857]

I been using .003 Intake and .006 for Exhaust on the SG for years. No burned valves.
Update....XS850! Nuts. I gotta read these thread more carefully. Must be getting old or something....

 

[jetmechmarty]

Just picked up a 1981 XS850. Runs fine but when it gets warm the idle will go up 3k rpm.
I am changing the cracked intake boots but also want to adjust the valves. Getting conflicting
info on what the intake and exhaust valves should be set at. Any help with the rpm problem
or valve setting would be appreciated!

Is this the XS850 triple? Shim over bucket?

 

[ekestle]

Yes XS850 triple over bucket. The book said intake .16mm to .20mm. Another thread I read said .11mm to .15mm.
I was told that the 80 and 81 was changed to the .11mm to .15mm. Not sure which one is correct. Thanks,

 

[jetmechmarty]

The later spec is to make the engine quieter. You may use the earlier spec without reservation. You will hear more valve train noise. So, choose based upon that.
What book are you using?
My answer is based upon my experience with the XS1100, so keep that in mind.

 

[ekestle]

Clymer manual Yamaha XS750 & XS850 1977-1981.

 

[jetmechmarty]

Clymer manual Yamaha XS750 & XS850 1977-1981.

A factory book would be nice if you can get one. Go to the 80-81 spec because it went from 750 cc to 850 cc. So, in addition to valve train clatter, the engine had other changes. It appears the Triple forums have gone the way of the dodo bird.

 

[ekestle]

Thanks for your help

 

[650Skull]

Biker.net has the 80G owners manual
http://biker.net/owners_manual/xs850g_owners_manual.htm

More Biker.net XS750/850 info
http://www.biker.net/triple_parts_index.html

PDF for the parts manual below

 

[ekestle]

Thanks Skull!