Looking for thoughts on a cruising speed problem.

In 6th gear, at 115 km/hr, and around 5500 rpm the bike can start hesitating and surging, basically heading towards no power, but not always. Maybe 10-15 mins. into a highway cruise  it can start and cause me to kick it down 2,3,4 gears and get it going again and then it will run fine . The first time it happened I pulled the clutch in to down shift and it just flat out quit.

In a lower gear, say 2nd, and the same  rpm of about 5500 rpm, i can maintain a throttle position but not get the same problem. I have also had runs of 45mins or more cruising in 6th and not had it occur. I have also had it happen in 5th, again while on the highway. But it has now happened four times   (always above 110 km/hr and on a highway) in the last week and I need to fix this. I have been on the bike for an extended weekend ride and racked up close to 3,000k, so not all is bad.

The carbs were cleaned this past winter, 8000 or so km ago. It is a 99 with 42000 km and  has been fine up until a week ago. I had access to another ignitor box, so this has been swapped and I will try tomorrow and see if it still quits on the highway. Anyway, I would appreciate any thoughts from those more experienced and wiser than i. Thanks

I was having the same problem when I first got my bike, I cleaned then synched the carbs and put an extra ½ turn out of the mixture screw put and the bike ran great.

I would also check fuel hose for kinks or getting compressed also look to see if the petcock is set to fully open or not just closed a little.

What year?  Older models that have the original petcock often have starvation issues at high speed.  Do a search to find out more.

Hi again

Thanks for the tip on fuel petcock posts and have been searching through them. That certainly sounds like the problem and it is still with me. Had to hall the the bike home on the back of my pick-up yesterday as I could not get it to re-fire like other times after an hour. Bike is 1999, 500e with 42,000K carbs were off and cleaned 5,000k back and synched. Bike ran fines until a couple of weeks ago on a long weekend ride.

I have both the frame petcock and the tank shut off of the bike and on the desk. The filter on the tank shut-off looks clean, However, lots of posts about making sure the off/on screw is fully vertical (what a horrible positioning) if you site through the tubes to the filter you can see that even fully open neither of these are are more than fifty percent open. Is  this the way they are suppose to look. The flow is cut in half even when fully open!!!!

On the frame rail petcock , again everything looks good and as far as I could tell the rubber membrane is intact. I do not know that I want to do the vacum bypass number. Anyone else with the problem just by a new petcock at the rail and have that be fine. And has anyone else looked at the tank one and seeen this gate that never opens more than give or take 50%.

Appreciate any help. Thanks

not sure if you tryed it before taking everthing apart but try running it on prime.if that fixes the problem you have a bad petcock or bad vac line somewhere if this doesnt fix the problem you may have a gas tank vent problem

Hi
No, i had not run it on prime put i did try restarting with prime after it died this time but no luck restarting even after waiting an hour. Opened the drains on both float pools and they did leak fuel. Brought her home on the truck and today removed and cleaned both fuel valves and cleaned the filter. They are back on and the bike fired right up. Now when I get a hand tomorrow I will take it back on the road and see if it happens again.

I think it has something to do with the fuel delivery and if it does die again I will spring for a new frame petcock again.

Thanks for responding. every little bit helps.