There are many reasons why an early 4 valve K bike may rough when it gets warmed up but a fairly common one is an overheating ignition amp. What happens is that the heat sink compound between the ignition amp and its mounting breaks down over time, exposure and many heat cycles. This causes the ignition amp to overheat and not perform optimally.

Since this is usually overlooked during a bike's lifetime, even if this isn't causing your issue then it doesn't hurt to do this anyway as a maintenance task. It is a simple and easy task. Getting the battery out of the way is the hardest part.

Remediation:

The ignition amp is located on the front left of the battery tray.

All you need to do is remove it (2 M4 bolts), use sand paper or steel wool to remove the old dried up heat sink compound, and then apply a new coat of heat sink compound.

Any heat sink compound (a.k.a. thermal paste), like that used for computers and circuit boards, should work well. I used to get mine at Radio Shack before they nose-dived.

© 2024 Drake Smith - Please do not use or reproduce this elsewhere.  Feel free to link to it though.