Strange troubles with '89 GS500

[cchocjr]

Greetings,

A friend of mine and I recently cleaned out my bikes carbs, replacing the gaskets, o-rings, etc. While doing this, I decided to put in 40 pilots, 127.5 mains, 2 #4 washers per, and 3 turns on the fuel screws. Basically, I followed the formula on the re-jetting matrix for a stock exhaust w/ K&N drop-in. I also replaced my spark plugs.

So the problem...
The bike starts up great, and I no longer have to use the choke. I ride about 20 minutes on the highway, with great performance I might add. After this though, my idle begins to fluctuate and drop during stop and go traffic. Eventually, the oil light will come on and the bike doesn't want to run anymore.

I actually had to pull off of the highway on the way home yesterday because my bike kept stalling on the highway (bad traffic, stop n go). I kranked my idle screw up way high so that I could get home and switched the petcock to 'prime.' During this adjustment, I could feel the carbs bucking like crazy.

I'm thinking that I might need to resync the carbs (don't know if that's ever been done). I'm going to check the spark plugs to see if the mixture is too rich.

What is strange, is that after a day of sitting, I can start the process all over again...the bike rides great for a little bit, and then the problems re-appear.

The problem seems to occur regardless of whether or not the petcock is in the 'on' or the 'prime' position, FWIW.

Does anyone have any experience with this sort of problem. Any guidance or advice would be greatly appreciated.

Many thanks,
Charles

[cchocjr]

An update:

Well, I decided to open the manual (Haynes) and read it rather than begging (what a concept) and read that the behavior exhibited by my bike (i.e. severe loss in power at idle) was likely due to an overly rich fuel mixture. With this, and the advice of my friend who helped rebuild the carbs, I checked out my new plugs (with no more than 50 miles on them), and they were utterly carbon-fouled.

I cranked both carbs back 1 full turn, rode for about 20 minutes, and the problem seems to be greatly, if not entirely solved. After another day or two of commuting, I'm going to re-check the plugs (put in another pair of new ones) and see what can be seen.

More to follow.

[Wrecent_Wryder]

34

[ducati_nolan]

Sounds like you may have found your problem, I'd check your float height too to make sure that isn't causing this too. but I don't get the oil pressure light 

If your oil pressure light is coming on while the engine is still running, that's bad and has nothing to do with the carbs. There's a few possible options

1. your carbs flooded the engine so bad (or with the engine off) that it got past your piston rings and dilluted the oil with gas.
2. you bumped a wire while working on your carbs
3. your oil pressure sender is crapping out

You may want to put a pressure gauge on the bike to make sure everything is good, but at least check your oil and if it smells like gas, change it.
good luck 

[The Buddha]

Oil light comes on ... and you're wondering if its the crabs
OK here is a dumb question ... do you have enough oil dipstick check
Cool.
Srinath.

[ducati_nolan]

And my standard advice for anyone who may have oil pressure issues, is stop using 10w40 and start using 20w50. It's fine for a new bike down to like 14 degrees F. so if it's an old bike (yours is an 89, that's old) or you have lots of miles, or it's warm (you're in Atlanta), or you ride it hard often, just go with the 20w50. Even if your oil pressure light is malfunctioning, the 20w50 is probally better anyways.

[Wrecent_Wryder]

I7

[The Buddha]

Our oil pump does a lousy job at 1200 rpm, but the light will not trip on unless its like 0 psi ... cos it 3psi (checked it with a guage) it didn't light up.
Cool.
Srinath.

[cchocjr]

Oil light comes on ... and you're wondering if its the crabs
OK here is a dumb question ... do you have enough oil dipstick check
Cool.
Srinath.

Crabs? Who said anything about crabs?

Oil is full. I associated the oil pressure light with the carbs because I had just finished working on said carbs...and basic trouble-shooting tells you to look at what has changed in the system between stuff working and stuff not. It wasn't a leap, I thought, however...

After a day of riding, the problem seems to be gone. Idle is smooth, power is present at idle, etc.

I was able to adjust the fuel screws without removing the carbs, so not a big deal.

Like I said, I'm going to check the plugs in a day or two, see what there is to see, and make any needed fine adjustments.

Thanks ducati_nolan for the advice. The oil pressure light came on only when my bike was in the process of stalling out, but it certainly sounds like it couldn't hurt.

Thanks again.