84- 550 es, wont idle when hot

[amartina75]

when i first start my bike up it runs smooth, idles nice. I warm it up with the choke on within a min or two it's ready to ride. I can take it out for several short rides bring it back park it let it idle for a few min. and it's fine. i'll turn it off and start it back up without any problems. then i'll go back out and it will stall the first time i stop at a stop sign. at high rpm's there doesn't seem to be a problem. after the bike really gets hot it wont stay running. it is hard to start back up and dies generally after a few min or less of idleing.
I've had the carbs off several times cleaned and inspected them very carefully. put them back together very carefully. mixture screws set at 2 1/2 turns out. I am convinced there is no internal problem with the carbs. I've replaced all o-rings, including the ones that seal the carb boots to the head. i've cleaned and cheched the petcock, it's good and works when vacume is applied. checked the pickup screen its clean. i have two ignitors, runs the same when either one is pluged in. i've changed rectifiers and starters once. my old starter was worn and pulling to many amps killing the batt. i've replaced ground wires, had a fried wire. i have a supertrap exhaust on the bike, has not been jetted.
i've had this bike for two years now and it's never ran right i really need some help.

[80GS750]

almost sounds like its running a little too rich maybe? then once its warmed up good it cant handle all the fuel and is dying? i dont know i reallu dont know much. have you tried adjusting the mix screws at all?

[amartina75]

all the mix screws are set at 2 1/2 turns out. i have tried different settings before, further in and out, with no change in performance.

[nabrams]

You didn't say whether or not you checked the plugs when it dies out.
Are they black? If yes, then your idle situation is too rich. This will not be evident on start up from cold because bikes get richer as they warm up. So a bike that idles just fine shortly after start up may idle like crap once fully warmed. Now all this may apply only to idle because different carb jets affect mid-range and WOT.
Now, you say the problem doesn't seem to manifest if you keep the RPM high - I'm assuming you mean you're not missing or sputtering at all at high RPM even after the bike is fully warmed up. If so, that rules out any problem with the electrics.
If all the above is true, then it also may be slightly leaky float needle valves and/or large compression differences between cylinders - both of these would affect idle but not high RPM. You don't state whether or not you've checked compression.

[amartina75]

come on guys, need some help please

[nabrams]

come on guys, need some help please

You ask for help, but did you answer the basic questions I asked above:
1. Plug color at time of problem
2. Compression

Once you answer those it is possible to proceed further.

[amartina75]

i did try to edit the last post to answer your questions it didn't post. sorry. i'll try again.

[amartina75]

have not checked the compression because my compression tester doesn't have the proper adapter to fit. the plugs had a smooth black film on all 4 plugs. i pulled them before i rode today but not since i cleaned them and rode for a while . the bike has never misfired or sputtered. it runs good untill its hott, not just warmed up. it may take several rides before it starts having problems.

[nabrams]

OK, so the plugs are fouling - you definitely are getting too rich when the bike gets really hot - May be due to several factors (to be discussed after you get compression readings).
Knowing the compression numbers (two readings needed: right after startup and when really hot) will help to diagnose further. Compression degradation as the bike gets hotter can be due to several things (see other posts).
You've basically got to take the "process-of-elimination" approach here.
We've eliminated electrics. If compression checks out OK, then it can only be mal-adjusted carb settings/jets (those that affect idle).

[amartina75]

i just went out and pulled the 1 and 4 plugs they were black. but i was using the choke to try to keep it running when it was trying to stall. which doesn't make sence to me. when i put the choke on when it was already hott. it would bog for a second but then the rpm's would jump way up. i would expect the choke to just kill the engin especially if it's already running rich. i dont know i am pretty much at a lost now.

[amartina75]

ok i'll go out and try to find an adapter for my compression tester and get back to you, thanks i'll post my results, appreciate your time.

[amartina75]

if the compression was bad it would be burning oil, oil fouled plugs not gas fouled. and it would be worse when it was cold not hot. I am going to turn the pilot screws in 1/2 turn to lean them out and try a step hotter plugs and see what happenes. any one else have any insight to offer?

[Guest]

You mioght be fouling plugs because of a weak battery and charging system = weak spark. Break out your multi meter and do the stator test with the stator papers.http://www.thegsresources.com/gs_garage.htm

[nabrams]

if the compression was bad it would be burning oil, oil fouled plugs not gas fouled.

NOT necessarily true! Zero valve clearance is the MOST common cause of low compression - no oil fouling there. Now, bad rings do lead to oil fouling, but that is not what is most likely. You said your problem is only at idle - which, like I said, may certainly be due to poor and/or uneven compression. A head gasket leak can also lead to poor compression and not result in oil fouling.

Now, this time you reported that 1 & 4 were black, but last time you reported that all 4 were black. If that is still true then the other possibility is that your battery is dying down at idle leading to poor spark (as chef1366 said). BUT, if that were true then you would have difficulty cranking the engine with the starter the next time you started the bike from cold (which you did NOT report, so I'm assuming you don't have this problem).

[amartina75]

i'll check out the charging system again, i checked everything last year and was fine. I really dont think it has anything to do with compression. the bike only has 13,000 miles on it, and it runs great exept when idiling hot. also i said I only pulled the 1 and 4 plugs to recheck them, they are the only ones you can get to without taking the tank back off.