Rough Idle - Arching HT Caps

[ajaycad]

Got a bit of a problem...I have a 2003 Max 2500 miles on the clock and a real minter. Suffering the hot engine idle problem. Did a bit of research and was convinced it was the ususl HT caps leaking current. This was confirmed when returning from a ride I let the engine tickover and lo and be hold once really hot it started missing. I could also hear the arching when riding !!
A check of the HT caps revealed a nice little firework display. So I ordered a new set of NGK Caps, and fitted them. The plugs were changed last year, so are only 700 miles old. I did not change the leads. Now the arching is worse with the new caps

It is now arching on 3 caps where as before it was only doing it on two!!
Any ideas ??

 

[naughtyG]

I would change the leads if I were you.. You can buy HT cable by the length, simply cut it to size and replace. It is screwed into both the caps and coils.
Bit of a PITA to get to the front coils - they're hidden under the TCI box. Also notice that the FL coil feeds the FR plug, and FR coil the FL plug.

One mod many of us have done, is to replace the OEM coils completely, replacing them with COPs (Coils Over Plugs) from much newer sports bikes.

You can get a set of used COPs for about ?20-30 on fleaBay.

One member here makes and sells COP harnesses - I think it's $60 for the set.

 

[jfeagins]

Make sure you have GOOD voltages at idle. The CDI box loves to create problems at idle when the fan kicks in, IF you don't have good charging voltage. When mine did this, I went through 3 different sets of wires and plug caps, even changed out plugs twice and didn't make a bit of difference in the arcing @ hot idle when the fan came on. Getting the voltages back to normal, and a big battery mod "fixed" my arcing problem.

Don't even ask me how perfectly good wires and plug boots could arc to the valve covers, for any reason, but they do. I nearly sold my bike because of chasing this very problem, well, that and the carb/alcholic gas issues I was having simultaneously.