KH500 Lean Running Problems

[nevhunter]

Yes t does. Might be worth while checking the passage at the bottom of the float bowl too. Nev

[Les Carter]

Thanks fore your replies. I too had the polish filled fuel cap breather hole problem on my first ride after the rebuild it caused the bike to slow and stop and then refilled the float chamber in time for restarting and then repeated itself. Another problem I had when running in was the magneto drive gear came loose on the taper and it stopped. On refitting I noticed some play in the magneto drive end bearing and also in the ATD which when added up is quite alot. When I took the head off I checked the timing and found it to be reasonable at retard but when wedged on full advance one cylinder was all over the place much too far advanced. The mag was refurbished by Tony Cooper so I have no doubt it was OK when I first fitted it. Could it have been damaged when it came loose? The ATD was not provided byTC I got it off the Internet before I learnt of him. Am I a victim of the saying 50% off carb problems are ignition?

[Roger Gwynn]

Variation in timing between cylinders is a common problem on twins and is caused by a points cam that is no longer symmetrical or a housing that is not concentric with the shaft. All the other components such as the ATD are common to both cylinders. Magneto repairers do not usually address this problem, there is one guy that does but it aint cheap. I spent ages swapping housings and cams around on my KH and had some success but when I changed to electronic there was a noticeable reduction in vibration and even tick over, the main advantage of electronic is the even spark intervals.

[paul.jameson]

Play in the magneto bearing will give you uneven points gap as the armature waves about. Take the magneto back to Tony Cooper for inspection and get him to put it on his test rig which shows the variation between the two cylinders. The test rig came from Lucas, I believe but it certainly works for this problem and Tony is an ace at correcting imbalance between the sparks.

[nevhunter]

IF the "colour" on each exhaust pipe is even you are lucky on a vertical twin. Uneven muffler back pressure can cause differences. Retarded on one is worthwhile correcting at the beginning of your fine tuning. On the face cam type check everything for wear and leakage very carefully and time with a disc to 36 degrees full advance. Nev