Odd problem today

[klarowe]

I took my bike (83 GS550E) to work today and while on the highway doing around 60mph (i think it was around 6krpm) the bike randomly just completely started losing power and finally just stalled right out (yea, that was quite scary in the middle lane with traffic on either side... until someone finally let me through to push it to the side). Once I got to the side it would not start at all. Then i decided to turn the petcock to prime and it instantly fired right up and ran great. After about 5 min of riding I turned the petcock back to "on" and it didnt give me another problem. Any ideas?

On a second note, about a week ago I was out for a ride and the bike did a similar thing... at the time I thought it overheated because I limped it to a nearby stewarts, let it sit and it ran great again. I had put 5w30 in it temporarily as it was all I had before the ride so I just figured it was due to the incorrect oil, which made it overheat... but with today, Im not too sure.

thanks again

kenny

[Big T]

Clogged gas cap vent hole is most likely culprit

When it goes bad and you take the gas cap off, is there a hiss of air into the tank?

[Dave8338]

Sounds like the vacuum diaphragm is a little sticky. It has nothing to do with the oil you put in it though I would dump it ASAP...

Remove the vacuum line to the #2 carb and the fuel line to the fuel tee. With the petcock in the RUN position, suck on the line. If you see fuel running out the fuel line and can produce this several times, I may suggest a new petcock. If there is fuel in the vacuum line, you need a new petcock. If you don't like being stranded in traffic, you need a new petcock. I think you see my logic...

[GS550ES-Hank]

Mmmm... fuel tank vacuum locking? Petcock on the way out? Although, mine has done this just last week, and I couldn't find the cause either.

Check the petcock operation manually, and the vac line going to it for a small hole, crack, etc. It might be that it isn't getting enough vacuum and the carbs are draining the bowls slightly faster than they can be filled.

Check to see if your tank vent is clear of stuff with a spray can tube, and see what happens next time, though keep it off the highway till you're sure it's okay.

:EDIT: Okay, wow, you all are quick! Like minded, yeah?

[klarowe]

ok stupid question, where on the cap is the vent hole??? I can almost guarantee that is the problem b/c when I painted the tank I never even noticed a vent hole so its probably painted over (dogh)

[GS550ES-Hank]

The vent hole is under the cap on the rim. Don't feel too bad, I did it too. Grab a WD-40 nozzle tube and poke into it. It's not that deep, so you shouldn't need to shove the whole tube in there.

[klarowe]

if its under the cap then i probably didnt paint over it cuz i left the cap on when i painted... but I'll clean it out when i get back to it (left it at my dads after work as it was already raining and I didnt feel like bringing it home.. lol)

[klarowe]

rough shot in the dark, but does anyone have a complete vaccuum hose diagram... something that I can use to go through and make sure all of my vacuum lines are in good condition and not leaking... and are existent... lol. I have already found 1 bad hose, and 1 hose completely missing.

[GS550ES-Hank]

Well, you should have one vac hose going from the right carb to the petcock, and the crankcase vent to the air box... I really don't think there are any more on it. A couple draft tubes for venting purposes. This is an '83 GS550E right? TSCC and everything? Is it a California model by chance? They had a rudimentary emissions control system on them with tons of vac lines, but the Federal ones didn't have much on them.

Also, on BikeCliff's website, there's a PDF version of the 83-86 GS550E/ES/L manual. It should have a map of all the vac lines in there. Also a must have. Very useful. As time goes on, I'll be doing almost every maintenance task I possibly can, as well as a few mods, so if I've done it, feel free to ask a question for a tip or help. There's also an 83-86 GS550E/ES/L owner's group (Community-Social Groups at the top of the page) for people with these bikes.

[eddiev]

See the recent post titled "Did I kill my petcock". I posted a picture there to answer a carb hose question. As you may know we can't post the same pic twice on this site so I couldn't attach it here. It is from the basscliff site as someone said.
Hope it helps.
Eddie V