1980 GS550 dies in traffic

[Anonymous]

So this bike runs absolutely perfect. except for one problem?

When the bike runs at high idol for long periods of time (like the highway) and then has to idol low (like when I get to a red light after the highway) it can not hold it's 1100 rpm and dies. It will start right back up again but sometimes will still do it unless I fight it and give it a bit of gas. The problem seems to go away once the bike cools down a little. Any suggestions?

[Planecrazy]

There is a vent tube coming off the carbs that seems to be responsible for a variety of somewhat similar problems, and when you simply pull it off the problems go away.

My 1980 GS550L would run perfectly under most conditions, but get it on the highway for awhile and eventually the bike would begin to lose power until finally with the throttle cranked completely it would sputter down to nothing and die. After sitting on the side of the road for five to ten minutes it would again start running normally, as long as the rpms were kept down.

I spent years checking a variety of potential problems with no improvement, including electrical, fuel, etc. Several others with similar problems reported that pulling the vent tube takes care of it. I haven't tried it on mine yet, but suspect it's going to work based on what others have reported.

Hope this takes care of your mystery as well...

Steve 8)

[Anonymous]

thanks for the advice, but unfortunetly those tubes do not exist on my bike.

and the last time i pulled off the carbs and cleaned them (about 2 months ago) i made sure those vents were clear.

any other suggestions?

[Planecrazy]

One of the things I tested for (and thought was a strong possiblity) was a clogged gas cap vent. The theory is that after running at higher rpm for awhile a vacuum is created in the gas tank, and that starves the engine for fuel. The next time you experience trouble try pulling over, opening the gas cap, and listening for a "whoosh" that would indicate air being drawn into the tank. Also, the bike will start to run properly immediately after doing this if the vent is indeed clogged.

Hopefully it's something this simple. Then you can just disassemble the cap and clear the clog...

Good Luck!
Steve 8)

[chuckycheese]

Yep!

I think Steve's got the answer! (Also, you may notice it more on a hot day than on a cold one.) :?

[Anonymous]

thanks. i have cleaned it out before and it seemed to get rid of the problem my bike was having with bogging between 5000 and 7500 rpms.

And considering i just ordered a new one from bike bandit cause my friend lost my gas cap and had been riding it around for 3 days without one while not realizing it, i'm sure this will cure the problem. thanks!!