Stumped by a 850

[Mike Curtis]

Things seem to alright one day next day gone to hell.
New intake boots , new airbox boots, carbs cleaned etc.
One day the bike runs well idles great next day bike just starts and quickly dies now on the quickly dies part will not keep running.
Help

[wizard]

Did the bike run well before all the work. If so, whatever work you performed becomes suspect. Check all the seals on the boots, make sure they're seated. Eliminate air/vacuum leaks as the source. Is the vacuum hose to the petcock loose? Try it on the prime setting. Make sure the fuel supply is correct, then go to the ignition system. Loose connector to the coil? to the ignition switch? A sometimes problem like that would tend to be electrical, but you should eliminate the fuel/air supply first.

[Mike Curtis]

Bike did not run well before I went thru the carbs and airbox to make sure everything was correct and tight
Did find a bad ground on the bike before and corrected it bike ran well except for running rich even with this the bike started and idled have done nothing to it, now this problem.
It fires but quickly dies

[bwringer]

Are the plugs fouled?

An engine will sometimes run OK on fouled plugs when warm, then won't start the next day when cold.

You may have simply run/idled too long on choke or you may need to chase down whatever's causing it to run rich.

Don't give up! There's always a logical explanation.

There are way too many GS parts on eBay anyway.

[rustybronco]

Just throwing things out there, some already have been said.

pull the fuel line @ the petcock and check for fuel flow on prime, check plugs for color, wetness ect., check spark to plugs, try starting without the gas cap. like you said it didn't run right before you did the work.
You'll get it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[focus frenzy]

clean the contacts for the fuses.

[Mike Curtis]

Yes I've changed out two fouled plugs & your right have to leave on choke until it's warm.
I'm thinking float levels my cause the running rich problem is there anyting else that I should look at?

[JayH]

How did the air filter look? How about the quality of the foam?

[flyingace]

Two fouled plugs will keep the bike from running pretty effectively. Which two plugs were they? 1&4 or 2&3 may indicate a weak coil. If not, your fuel delivery is out of whack - check your petcock, float levels, etc. Beyond that, maybe debri in the idle/off idle circuits - you'll have to dismantle the carbs and clean them.

[duaneage]

Runit on Prime and test. Sacrifice a live chicken and throw salt over your shoulder.

[Mike Curtis]

Plugs 2 & 3 were fouled , airbox is tight have a K & N filter in the box seems to me clean but will clean and see if it makes a difference may look into pulling carbs and recheck float levels and check all ports.
Got to be in the fuel delivery I have good spark at plugs.
Thanks

[wiredgeorge]

What plugs are fouling? Knowing which plugs will allow you to take a guess on whether the problem is electrical or carb related.

Also, if your bike dies quickly, suspect fuel delivery issues. If you have a vacuum actuated petcock, try leaving the fuel cap open and try starting it on "PRIME" instead of the "ON or RUN" position. You may have either a vacuum block where the gas cap venting is plugged or the diaphragm in your petcock not functioning as it should.

And howdy to a fellow Texan from the Hill Country!

[flyingace]

Mike,
If you can't find a problem with the carbs, you may consider swapping the coils. I don't think it's that difficult. If the fouling goes to 1&4, you know you need a new coil. It may look like a good spark, but it could be intermittant or weaker than the other coil.