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Discussion Starter · #1 ·
OK... I completely cleaned and overhauled the carbs,rejetted to 90/122, removed h-box and mufflers now have straight pipes with baffles, and also went to pod filters, syched carbs and later found an electrical problem(partially blown metal fuse effected how bike ran) no more electrical gremlins. However now riding down the road between 3000-4000 rpm bike really runs like it has a miss and backfires out of right side, at times also feels like the right side completely shuts down... absolutely nothing, when this happens bike wont go over 4500 rpms or so and runs terrible. it actuallty died on me and would not restart, got home pulled the plugs, and they were dry and checked for spark and they both had spark. only thing i can think of is to put a spark tester on and go for a ride to see if the coil is cutting out when it runs bad but other than I am at a loss. Any help would be greatly appreciated.
 

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Discussion Starter · #3 ·
no sir, but i did drain the tank as much as possible and filter it with 2 paint strainers when pouring it back into the tank and it is on the same gas
 

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Discussion Starter · #4 ·
ok today i pulled off carbs checked them over still clean some water drops in right carb happens to be my problem child at the moment,reinstalled them, drained all the gas i could get out of it, this is the same tank of gas that all of my carb problems have started with, so eliminated that one. Gas tank was mostly clean inside some crud along bottom not enough to worry me, installed an inline filter between tank and carbs and added new gas. as usual started fine idled good til warm and then developed a miss, idle, miss, idle fine, miss, fine etc... almost set a watch to it. ride it 3000-4000 rpm range miss and still seems like right side cylinder is cutting in and out, when cylinder is on bike runs fine btu when it seems cylinder goes down no guts and can barely rev over 4500rpm range....still lost and losing hope
 

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Discussion Starter · #5 ·
tried checking the coils today by switching the connectors and plug wires, plug wires where about 2 in or so too short, will work on that tomorrow. let bike warm up till the miss started and pulled the plug wires on side at a time bike died on either side. Not ruling out coils but am now starting to think not getting enough fuel. I even tried pulling top of carbs off and "shimming" the vacuum needles so they open a little more dont know if it helped only had enough shims for 1 on each side. Will see how much temp guns are when tool whore comes in tommorrow and see if one side is running hotter or not.... any advice from the knowledgeable folks here would be much appreciated
 

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Discussion Starter · #7 ·
i was going to do that but wires going down to plugs where 2in too short, have a friend that is going to look for longer wires in his bag o' tricks tommorrow so i hope he has some for me to try. thats without pulling the coils and swapping their position in the holder.
 

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The spark units are 2 small, finned alloy boxes that will either be behind the right sidecover to the right of your battery or under the seat. I think under the seat on a custom.



I'm working on a mates 650 at the moment which has a faulty spark unit [fires erratically]. Swapping them quickly showed the problem component as the stuttering right cylinder became the stuttering left cylinder.
 

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Discussion Starter · #9 ·
ok today i switched the connectors around at the ignitier boxes and no change with the miss, I also sprayed everywhere around the carburetors with carb cleaner and got no change in rpm either direction. still trying to figure out longer coil to spark plug wires as mine are not long enough to go to the opposite coil to check the coils themselves. when the bike started to miss i unscrewed the drain on that side carb bowl and gas did come out so it is getting fuel not sure its enough but am running out of ideas
 

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Let the fuel from that carb run into a jar for at least 30 seconds. Otherwise if you have a restricted supply to that carb you will drain the fuel that is in it and not find out if fuel is continuing to flow into the carb at a reasonable speed. If it's not flowing in fast enough it will not keep up with engine demand.



As for the coil test, if you can't source suitable plug leads just physically swap the coil positions and wiring, it's not that hard.
 

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Did you take the fuel shut off to drain the tank? That way you can truly drain the tank.



Did you use an ultrasonic cleaner on the carbs per Larry's book? It really does make a difference.



You carbs will never function properly unless it is hooked up to a stock air cleaner or some system that give the same amount of vacuum to make the carbs function properly. You must also have the carbs jetted properly if you change the exhaust.



These carbs are not conducive to changing the intake and exhaust.
 
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