Diablo**

new rings put on still wont start, i put the old head back on with oversized bore and the bike started, so i think the carb HAS been rejetted for 250 head, have just bought a 125 carb repair kit with new jets and stuff so hopefully when that arrives i can put the 125 head and pistoon back on and she should fire up. ill keep u posted thamks for all your assistance

carb is standard not been rejetted normal 125 carb for a teazer

yeah one of the rings a little bit broke off, just ordered some new rings, would that be the cause?

hi have tried two plugs, gonna get another one to day as not sure if the two i had were the rite ones, as one came with bike and one came with new head, both sparked ok though. the head i took off had a 65mm bore and the piston wasn't rite it was slapping, i now have standard head which is 56mm bore and piston. would a broken ring cause the problem?

It seems ok,

hi i have had my bike a little while, had no problems til the thread got knackered on the head then it decided to crack, replaced it with a standard 125 head and piston, now when i try to start it, it will try and try then backfire and try some more but wont start. it was working fine before even though the head was wrong and it had piston slap, the spark is sparking petrol flowing and 2 stroke lubricating, i cant see why it wont start as all i have done is replace the broken head and pistons, please please help if you can as i love this bike and dont wont to blow it up which was on my mind after trying for 8 hours to get it working