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Discussion Starter · #1 ·
Hi,

Just got CX650c. Its new to me having just had CX500 euros so far.



After some trouble getting it started - turns out reserve does not work on the fuel tap (aaagh) - it runs real rough and wants lots of choke.



Checked the plugs and one of them was a little bit "yellow" spark. Replaced the plug with same result. Decided to swap the coils with the working well coils from my cx500 eurosport (same exact coils). This seemed to help but the bike still rides crap.



Riding down the road its spitting and jerking (even on choke), with the choke off same behaviour but will rev a bit better....at about 4k revs its done.....revving the bike in neutral it revs to about 6k revs but under protest and lots of stuttering. So I'm ruling out stator problems as it will rev beyond 6k revs but thinking fuel starvation etc



Took off the carbs...every thing clean..all jets look good....pistons move smoothly....mix screw set ok.....didnt check float height or didnt open the air cut off or accelerator sections (maybe a mistake !!)



Then modded the fuel tap to be non-vaccuum - its leaking a little bit around the little bowl (dodgy o-ring).



Bike still not running well......farting and splutting with the choke on...with the choke off same behaviour with lots of popping and almost backfiring ????????



I still suspect something in the carbs and am hoping to get carbs off a working bike a friend has in a week or so...if the problems remain then I'm maybe thinking electrical problem around a bad connection to maybe the coils somewhere or else the sparker units or something ??????



Anyone ever seen a 650 custom with issues like this before ????



Any help/advise appreciated.



Not trying anything else with my carbs till I test the bike with my friends carbs first !!

Eric.
 

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I would bet that your problem is 99% carb related. Maybe only the float height or non sealing float valve, as the fuel should never reach the top of the float bowl and leak out. Even if the floats were stuck, it should drain out the overflow first. So take the carbs off and check the float height (15.5mm), and check the operation of the overflow tubes in the bowl.



I doubt that these checks will solve your problem tho. I think you need to do a deep cleaning of the carbs with all the rubber and brass jets and emulsion tubes removed. These buggers have some very small internal passageways and are very sensitive to everything being perfectly clean and not obstructed. Just a perfunctory spray with carb cleaner doesn't cut it. Or even a soaking in cleaner without some probing and chasing passages may not get everything out. Ultrasonic is the answer, but there are other slower chemical methods that also will work.
 

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B)hi Eric ,Blue is normally spot on,so take what i say with a pinch of salt.............

i reckon you have an intermitant spark,cause by a bad electrical gremlin,could be a ht lead,plug cap,coil,possibly even your main fuse
 

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I'll revise some of my post, after reading the original one again. I thought you had fuel leaking out of the carb bowls, but I think you meant the petcock bowl. So float height my not be causing the issues. I still think it is carbs, but Bandit does have a point. Check those resistors (does the euros use resistors?), and for a couple of bucks, change out the high tension plug wires. Just get a solid core plug wire and screw the plug caps on the end and screw the wire into the coils. A cheap preventive thing even if not really needed.
 

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Discussion Starter · #5 ·
Thanks for the posts guys.



Yes, it is leaking from the little fuel bowl on the fuel tap - a well worn o-ring I think - not a major problem.



The coils and leads are good - they are just off my running fine eurosport so I'm 99.9% sure they are ok. What I would not be sure of is the wiring from here back to the loom - and someone did reccomend I run a wire from the earth wire on each coil back to the battery to eliminate a bad earth to the coils - but saying that the plugs have a good blue spark when I crank over the engine - so unless they're failing under load they are probably ok.



I still suspect carbs so will wait on the "known" good carbs from my friend to test.



Thanks,

Eric.
 

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Discussion Starter · #6 ·
Known good carbs are on the way so when I have those I'll fit them and hopefully the bike will run fine.........if it doesnt then the fun begins !!



Eric.
 

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Discussion Starter · #7 ·
Known good carbs arrived from my buddy in France. Fitted them over the weekend - two words "fitted them" makes it all look too easy - changing carbs on a cx650c is a pain in the ass - first time I nicked the water pipe - 2nd time I was more careful but it is a very tight fit !!



Went for test ride - after a little splutter it ran like a beauty - done about 20 miles and ran great - good torque and acceleration.



Have the old carbs here to look at but thats another days work !!



Eric.
 

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great news Eric,thanks for the update.

its not just you by the way....650 carbs are known to be a very tight fit.many members here have lost some skin off their knuckles
 
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