I have a MC18 that is backfiring from the top cylinder. The bike was running beautifully last track day, a couple of weeks ago. The other cylinder is running fine. But the top cylinder is not running then backfires every so often.
I figured it must obviously be either fuel, air or spark. So I changed out the carbie for a spare unit, same problem. I read the topics about the coils, so I put on a new coil, swapped coils, cleaned connectors etc, same problem. I checked to see there was a spark and it was sparking fine. I put in a new plug as well
I removed the exhaust to check no blockage. I checked the reeds and they are fine but swapped left to right anyway. Still same problem.
I checked and cant see anywhere that is allowing an air leak on the cylinder.
I love this bike as it is real ball tearer but I am not having much success diagnosing this problem. Any help would be greatly appreciated.
I have 2 x MC21's as well both going through ground up rebuilds. I have a lot of spare indicator lights, undertrays, oil containers, some fairings etc, all the stuff not required on track bikes. These are free to anyone who wants to pay for the postage. Better than going to the dump. I am based in North Queensland Australia so email me if there is something you are after.