so, I've had this annoying backfire since I put on slash cut & changed jets. started to think it might be an exhaust leak. checked & re torqued one of bolts where header goes into head & tightened down the muffler clamps (well, one of them).
still pop & bang.
so sceptic that I am thought I'd try Lancer's simple carb tune (how can anything so simple cure a backfire, I thought).
I did the first part & turned the screw in until engine started to slow down, counting turns in. then went back to where it was originally & started to turn it out. did not seem to matter after a turn or two - did not seem to speed up & then slow down.
so what the heck - I twisted the throttle & let it go.
no backfire! repeated twisting throttle & letting it go - still no backfire!
put on coat, helmet & gloves (today is maybe a record here - in the mid 70s but I still dress for the job) & went for ride around town, stopping & starting @ lights (still no backfire & seemed to pull strongly) & went to see Lon (Thumperclone) to tell him news (he was not in but know he'll read this!)
so gosh knows what I did - like I said did not follow Lancer's instructions through to conclussion but arrived at same result.
so much for mechanic @ local shop who said after I asked his advice "Once you mess around with aftermarket mufflers it can screw up the bike for smooth running for good."
thanks to Lancer for putting me on right track & person who posted the instructions on the site.
me - a happy camper (doubly so - Ferrari won the first race of the Formula 1 season - my wife & I are fanatics!)