My bike was being suspiciously reliable lately, it must want something from me, a wash maybe. Anyway, this week after not getting what it wanted it threw all it's toys out of the pram and started stalling, usually just as you go to open the throttle. Not only this but it's down on power (when you've only got 9hp you notice a missing 1/2hp), and under heavy load at higher RPM you can hear the engine breaking up a little, definately not a fuel problem, so I'm guessing the coil is on it's way out. I would test it but my multimeter also threw a tantrum and a new coil is cheaper than a new meter.

What do you guys think? 

Changed the plug and cap recently?

Always, ALWAYS job number 1, keep the old ones too.

You may get duds out of the box. If you ever change a plug keep it till the next time you do as a known 'good' one.

Makes diagnosis much easier when you have components that are certain good.

as above plug first, lead your way back from there

check in the dark for stray sparks, as if this town ain't big enough for the both of us

 

Tried replacing the plug, didn't think it might just be a plug cap. I'll give that a go and see if it helps, it seems in good condition but a brand new NGK part is only a few pounds so won't harm anything to give that a go before forking out for a new OEM coil.