Postby Hasbeen » 13 Apr 2011 01:57
Stephen, I did not have a problem with idle, after doing the exhaust, & inlet. It was at higher revs I needed the richer needle. The thing would not rev past about 3500 RPM without those needles.
Was your backfire through the carbs, or the exhaust? I have found backfire through the carb is usually caused by closed up inlet valve clearances, or indeed a riding valve.
Backfire through the exhaust has usually been down to sucking air in somewhere it shouldn't, or one of those damn fool air pumps pumping it in.
Bad idle has usually been down to unbalanced carbs. One doing all the work, & the other admitting very little, or virtually no air at all at idle, or the float level being so far out on one carb, that it provides little fuel, so its cylinders are running very lean, below 1250 or more RPM.
Unless it's a spark plug problem, or a coil or a lead or------, well you know the rest.
Of course you still must uprate those needles.
Hasbeen
