She won't run when warm!

[EastBoundAndDown]

Got my GS500 worked on today by a guy who is great with carbs. We cleaned them, set the float height and synched them. Bike ran terrible before, ran great after what he did. I rode it up the street and back, ran well and idled well.

Get ready for a real ride, and 2 miles from my house, it dies and will not restart. After a fee mins of cranking and me removing the retainer lip from my KN filter' it ran. Only at full throttle, and barely ran me home. Full throttle in 4th gear going 40mph. Will not idle, died once I pulled in the driveway.

So it runs great cold, but poor when warm. Could I just be rich? I rejetted for my slip on pipe. I am at 127.5 M and 40 PJ.

Thoughts?

[The Buddha]

89-00 I presume ?
Ok float height ?
The fuel hoses routed right ?

You have fuel ?

Cool.
Buddha.

[EastBoundAndDown]

Yessir, 1992. Bike sat for 8 years so I am trying to breathe new life into her. 2,600 miles.

I just put fresh gas into it, a couple gallons. I tried RES PRI and on, to no avail. It does seem like it could be a fuel starvation issue, I.E running the bowl empty and then struggling to run.

The float heights were set correctly. I will have to check fuel hoses again tomorrow.

[BockinBboy]

May sound silly, but its happened before... You remember to take the choke off after its warm? - and is the choke functioning properly (spring in correct position, cable connected and working right, etc.)?

- Bboy

[EastBoundAndDown]

Oh yes. She would not run right when warm, choke on or off made no difference.

Clogged petcock? It is an obvious fuel starvation, I will look at it further. Perhaps the tank is gunked up?

[adidasguy]

Make sure the choke cable is properly connected and the choke slider is going back & forth  and also pulls on the little brass choke thingie pistons.

Maybe you need a carb sync? Usually you do that after putting them on and the bike is running & warm.

[EastBoundAndDown]

Did another test today. Bypassed the petcock by running a line from tank to carb, with an of/off switch. Ran great cold, choke is correctly working btw, and I was able to ride it. It runs, but won't idle. It runs smooth to 5500 or so, then cuts in and out to 8000rpm, then won't rev past 8k in any gear or neutral. Rode it with the choke on also, same result. Maybe it does just need a carb sync.

[EastBoundAndDown]

Does the following matter?

If I pull either plug wire off while the bike is running... It stays running without a hitch.

[radodrill]

Probably should also ask what jets your guy put in and how he set the mixture screws; it's entirely possible that the jetting is wrong, but it may be as simple as adjusting the idle screw (throttle stop).

[Blueknyt]

i did a carb job once and had something simular happening. i found that i had pinched the emulsion tube O-ring under the slide guide. it was bypassing un metered fuel making it too rich. once the throttle was opened, another thing to check is if a jet didnt vibrate loose. start up really good when cold but sucked ass once warm.

[EastBoundAndDown]

I know the jets are 127.5 and 40. I installed those, and we cleaned them and properly seated them. Tonight I did another test, ran a few oz of gas from the tank into a clean water bottle, looking for signs of a city tank. Nope, clean as a whistle.

My guy did turn the two brass screws on the underside of the carb. Not to any particular setting though. Also, he said he lined up the butterflies, but he did not do a carb sync.

Next I will do a proper carb sync.

[radodrill]

My guy did turn the two brass screws on the underside of the carb. Not to any particular setting though.

That may very well be your problem; the mixture screws could be set way too rich.

[EastBoundAndDown]

What is the proper setting?

[Paulcet]

2.5 turns out is a good place to start.  But even 4 or 5 turns wouldn't cause the symptoms you have IMO.

[radodrill]

What is the proper setting?

It depends a bit on the jetting etc.  The stock setting depends a bit on the year, stock jetting, and market spec; but it seems to range between 1-5/8 to 2-1/4 turns out from lightly seated.  I'd start at 2 turns out as a base point then adjust as necessary.

[radodrill]

2.5 turns out is a good place to start.  But even 4 or 5 turns wouldn't cause the symptoms you have IMO.

4-5 turns could very well be just enough to flood the engine at idle; particularly if the throttle stop is a little low.

[The Buddha]

8k and up wont run ? in neutral ?

Cool.
Buddha.

[Blueknyt]

mixture screws should not effect anything other then idle.  sync-ing carbs can help somewhat, but i must have missed it, 127.5 mains with 40 pilot its good with stock airbox and filter with stock exhaust. if your running it without the airbox and filter tryin to test and tune its not gonna run worth shaZam!.   even when i was using stock in and out it was 130mains 40pilots on the jets.  as to syncing the carbs, simple method for you is use a sewing needle as  a feeler gauge. mark the needle with a marker, just a simple line that you can use to insert the needle to same point on both carbs. with carbs off and empty of fuel find the carb with the idle adjustment stop on the linkage and open the idle up till you can just slide the needle under the bottom edge of the throttle plate up to the line you marked. then adjust the screw for the other carb to open or close the throttle plate enough to slide the needle to the same mark.  open and close the throttle a few times letting it bump lightly closed and recheck the adjustment with the needle.  with these carbs, once your past 1/8 throttle your sync doesnt matter as much unless they are GROSSLY out of phase. I.E. toss a cat through one while the other is closed.

[Blueknyt]

UH, dont forget to turn idle back down to where the plates are just touching the carb throats BEFORE you attempt to start the engine

[EastBoundAndDown]

Bike has a Delkevic slip on, k - n filter. Otherwise stock. Before I had my guy work the carbs over, it ran like shot, by it at last revved through the rev range, and would redline in neutral.

I will do some more tinkering tomorrow.