Losing power at Highway speeds

[jlmoulto]

So I encountered what has been a baffling problem for me for a couple days. I purchased a 1980 GS850GL about six weeks ago. Has been running flawlessly. First click of the starter with no problems. Have put approximately 1700KMs on the ike since purchased without a stumble until this weekend. While riding at approx. 110KM/hr for an hour, without warning the bike started hesitating(like a surge). I put in the clutch and immediately the bike stalled. Coasted to the side of the road, had a quick look around the bike, got back on and fired up perfectly. Road for another 1/2 hour and than fueled. Drove same as above and repeated exactly except this time when the she started surging I rode it out. Going up a small incline doing 50 in 3rd gear by this time, I was using 3/4 throttle, the bike finally seemed to run fine and then started working normally again. Drove another 1/2 hour without a hitch. On the return trip the bike acted up once more but was able to maintain about 80KM/hr with the throttle basically at full until the bike came around again after a couple minutes.

First I thought it might have something to do with the bike being on prime all the time (Fuel cock broke) Thoughts? Checked sparkplugs and they are not fouled. Been back for a couple of days, put about 150KM on the bike and symptoms have not returned. Going on the highway this weekend again and wondering if anyone has a suggestion of something I should look at before I go.

Thanks.

[Anonymous]

Check to make sure the fuel filter, if you have one, or the petcock screen is not clogged. I'd start there.

[QuaiChangKane]

This exact thing happened to me a couple of months ago heading into the hills on the interstate.

I was starting uphill doing about 80 in the fast lane, and traffic was speeding up and beginning to pass me. I accelerated so I could change lanes to the right and let the cars go by (into a strong headwind, as well). I got across a couple of lanes, and was doing about 85-90 when I felt the bike start to lose power. I kept giving more throttle, until I realized that I was doing 70 mph at full throttle. Even uphill into a wind wouldn't normally have caused this drastic of a power loss on my bike, so I managed to limp over to the shoulder, where the bike promptly stalled.

I cranked the bike over and over to no avail for a couple of minutes, playing with the choke and the petcock. I was about to start checking for spark when I got the bike started. It ran rough for a few seconds, then settled into a normal idle. It's run flawlessly ever since.


The only thing I can attribute this to is cheap fuel. I had tanked up 30 miles prior to the problems with Arco 92 octane. I've since removed the petcock which had no signs of clogging, have checked the fuel lines etc., but could find no mechanical problems. I run only quality fuel now (and typically did before, but went cheap due to the CA gas prices), and never get gas from a "mom & pop" gas station - they buy the dregs from whichever truck pulls in to sell off the bottom of their tankers.

I'd check your petcock and see if changing your filling station helps...

-Q!

[SqDancerLynn1]

YOU NEED TO FIX THE PETCOCK, it may not be related to you current problem but it cound be a diaster waiting to happen. If one of the carb floats sticks the engine crankcase could fill up with fuel. Fuel does not compress if the cylinder is full and you try to start it you could bend a rod and distroy the engine. It could leak all over the floor thru the air box, can you spell fire!!! As to your problem I would check the tank vent, the gas cap vent, fuel filter, kinked fuel lines