Grant JohnsonSpeaking as an ex-mechanic - I've had lots of carbs come in that "weren't quite right and I've done everything" - and a full clean and reset to spec fixes them completely. Always!

Ideally you'd do a FULL clean with nasty chemicals to make sure the passages are really clean - air is NOT enough - and then set everything to exactly factory spec.


Hi. The cold starting problem is finally fixed. Thanks to all for the advice and for pointing us in the right direction because yes, the carb was the problem. The advice quoted above from Grant Johnson long before I added to this thread was pretty much a good part of the solution.

Though the carb had repeatedly been dismantled & cleaned everytime using various techniques and materials in cleaning the carb after the engine overhaul, what did the trick was when the mechanic rechecked the very small passageways in the carb body he called "venturi holes" and recleaned them using (sounds a bit extreme) pressurized butane in a canister such as that for refilling personal cigarette lighters. And thereafter, his heating up the carb body (with extreme caution after removing any parts that could melt) and cleaning the carb body in and out with kerosene, while the carb body was still heated. Very carefully because overheating the carb body would result in reclogging the passageways or worse, a burned carb body.

The XT has been firing up on cold starts on the first attempt, for 5 consecutive days now. Thanks to all again.