Ive had the same magnum project thingy for over a year and half. Its had a number of kits on it, it was previously not sealed right, and now it is....
Just a regular case matched e50 to a metrakit, 3 shoe and perf crank, nothing crazy, 19mm carb setup.
Since ive had this bike , its backfired with any kit ive put on it. One i soft siezed racing a kymco scooter ( yep im an idiot ) And another ive since moved to another bike. Now its got its 3rd kit on it and it still backfires.
The one thing i keep coming back too is that the points arc. Always have.
I replaced the condensor and point last year, still arc'd.
Rode it around all last year, but at wot or high rpm's every once and a while it would backfire. GO figure.
So this year, i replace the points and the condensor again, use those really nice NOS points and a nice new condensor, and they still freaking arc. So someone sensibly says try replacing the coil. So i do. Still arcing points
So today after losing my mind , i run up , grab a new stator, and a whole new condensor , and flywheel, and put the condensor in the stator, move the new points from yesterday over, and put the whole new stator over to the bike and put the new flywheel on.
The arc a lot less , but you can still see the odd spark now and then between the points!
I rode it and could not get it to backfire a wot, but it was boggy...
I realized the only thing left i havent tried is the damned spark plug wire - it looks good but , hey its all ive got left i havent tried.
I have tried advancing/retrarding and all sorts of gaps on the points.