CX500 GL500 650 Global

After the triple bypass, tried starting (with external fuel supply) and it ran until I cut it off due to copious amounts of fuel leaking from carbs. Tapped on the carbs which evidently seated the valves and stopped leaks. Tried restarting, only result was a tremendous backfire. Couple days later, tried again. Started for a few seconds and quit. When turning over, there's a hesitation like the timing is slightly off, or is this caused by backpressure? Read something in here about that which causes starter failure. Voltages are good. Set timing per manual when assembling engine. Have done nothing with carbs yet since the bike ran when I bought it. Timing problem or carb problem or both? Any opinions on which to tackle first?

Well I'm alost certain you will have got the cam chain timing ok as per,



Coz once it's all lined up it's actually hard to go wrong.This is for the 500 but I assume the 650 is the same in this respect?

Anyhoo.You said it ran for a short while so you know it can at least ignite.I think these are elctronic ignition as well(Not that it makes much difference in troubleshooting).

Backfires are 99% of the time caused by unburnt fuel in the Exhaust.Once you distrub the carbs on these bikes they can flood easy til they bed in and as you said tapping the carbs stopped the overflowing fuel(Carbs will have flooded).
I'd check for air-leaks especially on the engine side carb boots.Check plugs are getting a good spark then I'd crank the bike with the Air filter out and spray some Brake/Carb cleaner into the Guaze filter into the carbs and see if you can get it to pull through some fuel better and see if it will run.If you have to,make sure your battery is fully charged or jump it.

Aye aye. Thanks.

Jumpered my car battery and the bike turned over briskly with no hesitation, so rule out timing problem. Both plugs had strong sparks, however they were wet with gas when I pulled them. This tells me I have a carb problem and probably need to do a thorough cleaning/refurbishment. What say you?

mildhog wrote:Jumpered my car battery and the bike turned over briskly with no hesitation, so rule out timing problem. Both plugs had strong sparks, however they were wet with gas when I pulled them. This tells me I have a carb problem and probably need to do a thorough cleaning/refurbishment. What say you?

Yep.And you know who the,"New Kid on the Block" for All things CX carbs is

Ta Dah!!!!!!!

LRCXed

AFAIK I was the 1st person to really delve into the carbs on these bikes not just recycle the manual,

http://www.geocities.com/sheppola/carb/carb.html

But Larry has taken it to a whole new level


http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=7&t=32

Between you, Larry and Mike Nixon's manual, I should have no problems. Thanks.

Thank You Shep, but I cant take the bow without you.

mildhog, one of the main problems with these carbs, is if someone has rebuilt them with after market kits, the needles for the needle and seat assembly is manufactured a little to short. This makes them tend to be above the limit of what the carb system can handle. But, I do think you need to do a better cleaning at this point though. Read the carb cleaning post in this forum carefully and don't fudge on any of the steps, or the time it takes to soak them in vinegar. A couple days minimum, then get back to us.

aye aye

Update: Cleaned & sync'd the carbs and ran better but not smooth and tended to lope and sputter some. Thought timing was off. Adjusted valves and cleaned the spark plug caps. No timing problem but still not satisfied. Suspect the emulsion tube replacement from a GL500 carb may be at fault since it was not the same as original (more holes) though just a guess. Maybe it just wasn't clean enough. Disassembled and thouroughly cleaned another set of 650 carbs and installed and sync'd. Starts great, runs great and will idle at 800 rpm. Finally got it right. Moral of the story: Clean the carbs correctly and, in conjunction with clean caps and properly adjusted valves, you have a sweet running machine.

mildhog wrote:Update: Cleaned & sync'd the carbs and ran better but not smooth and tended to lope and sputter some. Thought timing was off. Adjusted valves and cleaned the spark plug caps. No timing problem but still not satisfied. Suspect the emulsion tube replacement from a GL500 carb may be at fault since it was not the same as original (more holes) though just a guess. Maybe it just wasn't clean enough. Disassembled and thouroughly cleaned another set of 650 carbs and installed and sync'd. Starts great, runs great and will idle at 800 rpm. Finally got it right. Moral of the story: Clean the carbs correctly and, in conjunction with clean caps and properly adjusted valves, you have a sweet running machine.

Just a word of caution.You say it will idle at 800 rpm but I hope you reset it to the correct idle speed as it's there for a purpose.Below 1,000 rpm the oil pump will not circulate the oil correctly and add to premature engine wear?