Firstly...Hello!

As usual, i am one of those who have been loitering in the background awaiting my confirmation email so i can get stuck in with asking questions and generally enjoying one's self which brings me onto my first question issue/question relating to my bike.

It is a 20 year old Kwack KLE500...i purchased it with this problem ( reflected in the price i might add ) and was keen to get my hands dirty sorting this, and a few other, issues out.

In a nutshell, over 6-7k revs in any gear it will run as intended for about 20 seconds, then will pop, buck, fart, lose speed, throttle response and all manner of PITA running...if i ease back on the throttle it'll calm down slightly but if i was to pull over she'll just happily die on me for 5 minutes before starting back up again...if however i continue to ride along at a lower rev then she will still backfire/pop/fart etc until i stop and she conks out ( see the waiting 5 minute rule ).

Now then, i do know abit about bikes ( how many have said that !! ) and from her behaviour i would say it's a cylinder not firing at the point she goes all wobbly on me, but is this a carb related issue or electrical?

I stripped the Carbs last night, gave them a clean although they were looking in pretty good shape ( one did have traces of rust in the float bowl, very minor and an old issue by the looks of it ) and installed back on today, i checked the coils and got 3.2ohm and 18k ohm on both and checked and maintained the air box was correctly fitted.

So any ideas my fellow KLE owners? Most point to the carbs but I'm chin scratching as to why it happens at high revs AFTER 20-30 seconds and not straight away...