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So just finished rebuilding the 360 and I can't get it to sync. I've adjusted the valves, set the timing with a pamco electronic ignition, and checked for vacuum leaks. When I hook up the sync gauge no matter which way I turn the screw it won't sync. The throttle cables are lubed and not sticking either.
So I was messing with it today and noticed if I pull the right spark plug wire off it idles fine and revs fine with just the left cylinder. When I attach the right plug again the revs shoot up. Same thing if I start it with only the right plug attached, just shoots right up. I have the mixture screws 1 and a half turns out as the manual states to start with. I also noticed I can feel slight electric shock from the handle bar when the right plug is not attached and the bike is running.
You have the handle bar ground jumper attached? Should be a small wire about 2-3 inches long with ring terminals on both ends going from the bottom of the riser clamps to the top fork clamp or somewhere that is grounded to the frame. That's only reason I can say for the shock feeling in the bars. Should be some measurements in the manual for the coils if you are using the stock ones. Be a good idea to test them to make sure that one is not internally grounding out.
Did you bench sync the carbs before you put them on? One cylinder running ok and one taking off sounds like that side has the throttle plate open more. If it is considerably more it will take off before you can get it adjusted back down.
Yeah everything's grounded correctly and I checked the coils. According to the manual everything is working correctly. I benched synced the carbs with a guitar string but when I fired it up for the first time and used the sync gauges it was reading way out of sync. One thing to note is that while I'm adjusting the sync screw the right cylinder gauge doesn't seem to move at all while the left will. in order to get the right cylinder down to idle rpm I basically have to bring the idle screw all the way out, which kills the left cylinder.
Yeah everything's grounded correctly and I checked the coils. According to the manual everything is working correctly. I benched synced the carbs with a guitar string but when I fired it up for the first time and used the sync gauges it was reading way out of sync. One thing to note is that while I'm adjusting the sync screw the right cylinder gauge doesn't seem to move at all while the left will. in order to get the right cylinder down to idle rpm I basically have to bring the idle screw all the way out, which kills the left cylinder.
I messed with it a little more today. No vacuum leaks. The only time I can get the sync remotely close (according to the sync gauges) is when the idle screw is almost all the way out (counterclockwise) and the carb sync adjusting is way out too (counterclockwise) but then I can't control the idle because it's too high (~2500)and can't be controlled since the screw is all the way out. WTF!
Pull the carbs and get them back onto the bench. If you back the idle screw out all the way, the left carb butterfly should fully close. Is this what you're seeing?
Pull the carbs and get them back onto the bench. If you back the idle screw out all the way, the left carb butterfly should fully close. Is this what you're seeing?
So a little update on the bike. The left cylinder had an exhaust leak that I fixed and that made the bike a lot happier. It really feels like its firing on both cylinders now when I ride it. So I rode it a couple miles and checked compression again and I'm only getting 120 on both sides after its been warmed up, choke off, and throttle WOT. I honed the jugs and put on new piston rings. I also tried to sync the carbs again. The left carb is working well and the needle on the vacuum gauge moves as I twist the sync screw. The right carb's needle still doesn't move at all with the sync screw turned all the way in or out. Maybe I should check the valves again? Timing might be off? I have a pamco electronic ignition.
Are both carbs really clean? dirt in the idle passages of one or both crabs will make it impossible to synch them.
How much slack is there in the "Pull" throttle cable? Loosen both cables to make sure that is not the issue.
If it revs high on both cylinders and OK with one plug cap off, that suggests that the idle adjusting screw is way too far open.
Which carb is the "master" i.e. has the cables attached to it? I think it's the left one. If so what "synch" screw are you adjusting - the air/fuel screw? and is that what you are adjusting on the right carb? Please check first that both butterflies are opening together (bench synch) and that they are both still opening together on the bike to be sure that there is not a slight twist in the linkage.
It does sound as if the right carb has a blockage in the pilot circuit.
OK so I'll pull the carbs off again, check compression, and give them both a cleaning. The pull throttle cable broke last night as i was about to go for a ride so I can't ride it anyways until the new one comes in.
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