Thread: Yamaha XT500
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Old 01-08-2013, 09:02 AM   #568
Sidecar Jockey
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Joined: Aug 2012
Location: MD
Oddometer: 484
More info on my smokey 1878 xt500:

It does not smoke at idle, or if it does its VERY little.

When I give it any gas at all, it starts smoking. More throttle = more smoke.

When I'm cruising or riding with the RPM's up and snap the throttle shut it smokes more. (The bike is constantly spewing smoke when I ride it or give it gas, but snapping the throttle closed makes the cloud get even bigger).

After returning to idle, the smoke stops within about 10-20 seconds.

I have put about 100 miles on it so far... and noticed no change in the smoke. I even poured some of that No-smoke magic stuff into the oil for the last 20 miles. No change in smoke. I'm usually afraid of that stuff causing more damage, but I figured i was going to tear the motor down anyway...

When I got the bike, it had 40 psi compression. After a good soak with ATF+ Sea Foam in the cylinder and in the valve inspection covers and a bunch of good kicks, the compression returned. Now its about 130-150, depending on how hot it is and how mant times I kick it. (3 kicks gets 130 lbs, 5 or 6 kicks gets 150 on a warm motor).

So, yeah, it had stuck rings. I'm tearing into the motor this weekend. Its already pulled and sitting on my bench. I will definitely replace the valve stem seals, and lap the valves. I'm also thinking that hitting the cylinder with a hone is a good idea to get rid of any glaze.

I ahve used a 3 stone hone for an electric drill on MANY motorcycle motors. I understand that is it just for de-glazing. I will of course be measuringt he bore and roundness of both the cylinder and piston first... but at only 1,200 original miles I really doubt that my cylinder or piston are past tolerances...

Thoughts? Advice?
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