Good evening all
I am in desperate need of some advice from those in the know.
My 03 Millie has been running rough for a few months now with a backfiring into the airbox on small thottle openings which has been gradually getting worse. Throttle bodies have previously been balanced using a gunson gas meter 1 3/4 turns out on front and 1 turn out on back. New plugs were fitted a few months ago so disregarded them.
However, today when i removed them i decided to check the gaps which turned out to be too big (0.9mm), now gapped as per manual recommendations to 0.6mm. I also decided to check valve clearances since my bike has now covered 11700 miles. I have only had the bike a few months so was unsure if the had been checked in the past.
On checking clearances it turns out all were within spec apart from one on the front cylinder, left hand side exhaust valve. which was reading 0.21mm with feeler gauges when the minimum is 0.23 as per Haynes manual.
Having completed all valve clearance checks i reassembled the bike until i order new shims. Since i had correctly regapped the plugs i decided to recheck CO levels using gunson gas meter, turns out they had changed from my previous setting of 3.5% front 4% back. I reset these readings usings trim pots and went for a spin.
The bike was running spot on with no backfiring into the airbox and was delighted with the results. However this did not last long, the backfiring into the airbox and stuttery feeling returned after a few miles with popping on the overrun also.
Took the bike back to base to recheck CO levels and to rebalance throttle bodies only to find that when trying to adjust the front bypass screw no amount of turning out or in made any real difference, where in the past small changes on the bypasss screw (out or in) made a considerable difference. I now cannot raise the idle level using front bypass screw (only screwed adjuster works) and the bike wants to stall all the time.
Please please can anyone shed any light on this problem? I am fearing the worst and thinking that my slightly out of spec exhaust valve clearance has something to do with it? It got dark shortly after this happening so will continue investigation in the morning.
Sorry for such a long thread, any help much appreciated.
Thanks and Regards
Gordon
I am in desperate need of some advice from those in the know.
My 03 Millie has been running rough for a few months now with a backfiring into the airbox on small thottle openings which has been gradually getting worse. Throttle bodies have previously been balanced using a gunson gas meter 1 3/4 turns out on front and 1 turn out on back. New plugs were fitted a few months ago so disregarded them.
However, today when i removed them i decided to check the gaps which turned out to be too big (0.9mm), now gapped as per manual recommendations to 0.6mm. I also decided to check valve clearances since my bike has now covered 11700 miles. I have only had the bike a few months so was unsure if the had been checked in the past.
On checking clearances it turns out all were within spec apart from one on the front cylinder, left hand side exhaust valve. which was reading 0.21mm with feeler gauges when the minimum is 0.23 as per Haynes manual.
Having completed all valve clearance checks i reassembled the bike until i order new shims. Since i had correctly regapped the plugs i decided to recheck CO levels using gunson gas meter, turns out they had changed from my previous setting of 3.5% front 4% back. I reset these readings usings trim pots and went for a spin.
The bike was running spot on with no backfiring into the airbox and was delighted with the results. However this did not last long, the backfiring into the airbox and stuttery feeling returned after a few miles with popping on the overrun also.
Took the bike back to base to recheck CO levels and to rebalance throttle bodies only to find that when trying to adjust the front bypass screw no amount of turning out or in made any real difference, where in the past small changes on the bypasss screw (out or in) made a considerable difference. I now cannot raise the idle level using front bypass screw (only screwed adjuster works) and the bike wants to stall all the time.
Please please can anyone shed any light on this problem? I am fearing the worst and thinking that my slightly out of spec exhaust valve clearance has something to do with it? It got dark shortly after this happening so will continue investigation in the morning.
Sorry for such a long thread, any help much appreciated.
Thanks and Regards
Gordon
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