bad backfiring on start up 83 xt 550
 

Hello guys my bike is a 1983 xt 550 runs great lots of power but on cold start ups bike is hard to start and u have to hold throttle open with full choke throttle half open for about 30 secs to a minute and it backfires threw airbox and exhaust (loud) then u can release throttle and choke then it runs good idels good but backfires when letting go of throttle does anyone no i cleaned carbs new aiflilter checked for vac leaks adjusted valves and recently replaced timing chain thanks for your help guys

Replaced the sparkplug? :confused1:
Also, check the inlet rubbers. Sometimes on older bikes they crack..

Vando

forgot tomension did that too

Sounds like the pilot system is blocked...... Clean carb out.
Or - if that don't work..... check spark/coil... should be a good + 12v to the coil.