OK... so my Dad and I spent a few hours going through my bike yesterday and most of that time was spent working on getting it to idle better. It idles OK at the moment, but not perfect and we like to aim for perfection around here.
These are the symptoms we are currently seeing:
*Left side is running cool. Even after idling for 5 minutes, the left pipe is only warm whereas the right side is quite hot.
*Occasional misfire on the left side that goes away above 1/4 throttle. This misfire also seems to get a bit better when I unscrew the mixture screw on that side but doesn't completely go away before the RPMs start to drop from the adjustment
*Timing is where we want it, but "wanders" a bit at idle. It fluctuates a few degrees in either direction and doesn't hold steady when we strobe it. The strobe seems continue to flash when the misfire occurs so I'm not convinced (but also won't rule out just yet) the problem is spark.
*Engine still runs with idle screw all the way out. Pulling the carbs verified that butterfly valves are as closed as they're gonna get (how is this even possible?).
*Mixture screw has very little effect on the left side as compared to the right. Turning the right side more than half a turn in either direction drops the RPM whereas the left side I can unscrew it two or three turns before the RPMs drop and RPMs don't drop even with it screwed all the way in (it's currently sitting 1.5 turns out).
*We switched the mixture screws from left to right with no difference in operation
*Tried running without the mixture screws at all (completely remove them) and bike will not even start
*Compression of left side is 150 PSI, right side is 151 PSI
*Initial timing is about 25° due to domed pistons and additional duration on the cam. Retarding to stock timing values didn't change the running (in regards to the misfire), but the bike was no longer happy to take throttle and RPMs dropped enough to require adjustment of the idle screw.
*Valve clearances were reset (I had them gapped a bit too much)
*Regapped the spark plug on the left side to .040" and then down to 0.25" with little difference in running
*Tried new plugs with no difference
*Carbs have been cleaned twice since I had the engine apart with the only change from stock being a move to 115 secondary main jets
My Dad spent some time thinking about this one and we're going to search for more vacuum leaks (I already replaced the carb boots because I did have a leak, previously).
Any other ideas?
These are the symptoms we are currently seeing:
*Left side is running cool. Even after idling for 5 minutes, the left pipe is only warm whereas the right side is quite hot.
*Occasional misfire on the left side that goes away above 1/4 throttle. This misfire also seems to get a bit better when I unscrew the mixture screw on that side but doesn't completely go away before the RPMs start to drop from the adjustment
*Timing is where we want it, but "wanders" a bit at idle. It fluctuates a few degrees in either direction and doesn't hold steady when we strobe it. The strobe seems continue to flash when the misfire occurs so I'm not convinced (but also won't rule out just yet) the problem is spark.
*Engine still runs with idle screw all the way out. Pulling the carbs verified that butterfly valves are as closed as they're gonna get (how is this even possible?).
*Mixture screw has very little effect on the left side as compared to the right. Turning the right side more than half a turn in either direction drops the RPM whereas the left side I can unscrew it two or three turns before the RPMs drop and RPMs don't drop even with it screwed all the way in (it's currently sitting 1.5 turns out).
*We switched the mixture screws from left to right with no difference in operation
*Tried running without the mixture screws at all (completely remove them) and bike will not even start
*Compression of left side is 150 PSI, right side is 151 PSI
*Initial timing is about 25° due to domed pistons and additional duration on the cam. Retarding to stock timing values didn't change the running (in regards to the misfire), but the bike was no longer happy to take throttle and RPMs dropped enough to require adjustment of the idle screw.
*Valve clearances were reset (I had them gapped a bit too much)
*Regapped the spark plug on the left side to .040" and then down to 0.25" with little difference in running
*Tried new plugs with no difference
*Carbs have been cleaned twice since I had the engine apart with the only change from stock being a move to 115 secondary main jets
My Dad spent some time thinking about this one and we're going to search for more vacuum leaks (I already replaced the carb boots because I did have a leak, previously).
Any other ideas?
