Dying when hot, broke down on highway... 3 times... in a row...

[POULSEN]

I would go for the filter and/or fuelline problem too.
I had a similar problem last year. The bike was running o.k. until I reached the highway - then after a few Km it lost power, and I had to pull over.
Problem was a bent fuelline, being able to deliver fuel a low speed, but at the highway the consumption rises drastically, and the bowls were emptied.
If i could hold it in idle, it would solve itselv within few minutes. If it died, I had to go to PRIme position before i could proceed.
Moving the fuelline to a slightly other position solved the problem.
I now it sounds too simple...
And I can't explain why you have to wait 15 min - but do you really ?

Stig

[tconroy]

The gas tank hole(vent) was clear. Turning the petcock either up or down doesn't seem to make any difference in the way it runs. Which direction is prime and which is run?(yes, I should have sought the answer to this question long ago, but like I said it's never seemed to make a difference) Now that I've read about the Priming function, I think that might explain some of the not wanting to start when hot, but I don't see how that would cause the bike to completely lose engine power(doesn't die until it comes to a stop) while on the highway. The airbox and pipes are stock.

As for a fuel filter, there is a small, clear, plastic, cone-shaped piece with what looks like little pieces of metal strips inside. This is inline on one of the fuel hoses. I haven't been able to find it any of the diagrams in the Haynes manual, but I've always thought it was a filter of some kind. Are these necessary? And what is the easiest way to check for vacuum line clogs?

They are not nessasary (but) I run one anyway just in case.They do have to be put on a certain way.You only have one fuel line from the petcock and make sure they filter is on the right way.There is a little arrow on it that will tell the fuel flow direction and also make sure it is below the petcock and vertical not horizontal. The fuel must flow down the fuel line not sideways.Back towards the rear tire is prime and straight up and down is run and towards the front is reserve.It should be marked on there. You shouldnt have to use prime unless it sits for a few days.I would try a new filter or take it off completely and get a new fuel line.

[DrDoot]

as it begins to quit can you goose it and get a slight speed increase.. ??

could be the coils getting hot.... check them for cracks and tar(ish) leakage..

does the filter have gas in it when you get off and look at it????

fuel starvation sounds very plausible... my pickup had a similar problem.. it was due to a glogged filter... cleared when replaced..

Joe

I couldn't get any speed increase with the throttle when it lost power. I could just slightly change the noise of the engine, but RPMs were just enough to keep the engine idling, until it slowed enough to kill it. I didn't check the filter when this was going on.

And as to TConroy's post, it sounds like it's a good bet at either the fuel petcock or the fuel filter. Which of these is most likely given that the bike won't start after it's been ridden awhile and then shut off, and that the bike suddenly loses power on the highway(after running fine for 10 miles or so), dies, and needed about 15 minutes of sitting before it would start up and run fine again for awhile? (The bike has been ridden regularly for a year and has only started to have problems with the warmer weather)

?

Also, the fuel filter has been in a horizontal position the entire time I've had the bike, can/does this make much difference?

Thanks much, answers to those two questions above should send me in the right direction with this.

[DimitriT]

I had a fuel filter in the horizontal position for a couple of months last year. It gave me problems when I ran near wide open throttle. It would starve like you describe after about a minute at WOT. I repositioned the filter to sit between carbs #2 and #3, vertically, and the problem has disappeared.

[tconroy]

I couldn't get any speed increase with the throttle when it lost power. I could just slightly change the noise of the engine, but RPMs were just enough to keep the engine idling, until it slowed enough to kill it. I didn't check the filter when this was going on.

And as to TConroy's post, it sounds like it's a good bet at either the fuel petcock or the fuel filter. Which of these is most likely given that the bike won't start after it's been ridden awhile and then shut off, and that the bike suddenly loses power on the highway(after running fine for 10 miles or so), dies, and needed about 15 minutes of sitting before it would start up and run fine again for awhile? (The bike has been ridden regularly for a year and has only started to have problems with the warmer weather)

?

Also, the fuel filter has been in a horizontal position the entire time I've had the bike, can/does this make much difference?

Thanks much, answers to those two questions above should send me in the right direction with this.

even though the bike has a vacumn it is still gravity fed with fuel so YES your fuel filter should be vertical. If you always fill your tank up before parking the bike AND there is nothing wrong with the inside of your tank it would be safe to get rid of the filter completely and replace the fuel line.That should be the cheapest way to correct the problem.You should be able to check you petcock by watchin the filter and turning it to the "prime" postion and see fuel flow thru to fill up the carb bowls.If this is your problem you are probably getting an air pocket that will not let enuogh fuel flow thru as the bike requires to keep it running.More of an air lock than a vapor lock.

[SqDancerLynn1]

If you are still having problems, remove the fuel filter & install a new 5/16" fuel line Make it short NO big loops, make sure the vents are not kinked.
ONE of the most important things to check --- Make sure the petcock is working properly. If after doing this you still have problems
check the ignitor. Take a bottle of ice water when it quits, douce the ignitor with water to cool it & see if it starts back up

[tconroy]

If you are still having problems, remove the fuel filter & install a new 5/16" fuel line Make it short NO big loops, make sure the vents are not kinked.
ONE of the most important things to check --- Make sure the petcock is working properly.

5/16ths I though it was 1/4 inch thats what on mine. I use the clear blue polyurethane fuel line and its much easier to see the fuel flow thru plus ther is no clamps, easy t slide on but wont come off if you pulled your hardest on it,(like a chinese finger puzzle) Wonta coma offa!

[roxymuddin]

Im a self taught motorcycle mechanic, but have been working cars for years and what this sounds like to me is a spark problem. I would definetly look at the coils, I have had the same problem and checked fuel pressures and filters, but has come down to the coils. If you have on put and inline spark checker on it and run the bike. The checker will have no effect on performance and if you put it on and outside cyl. you can see it while riding. Then when it bogs check to see how strong the spark is.

[crc1214]

I would "third" the petcock theory. One of my old Seca's did this. After about 3 minutes of 65 and above, it would do the exact same thing. The first time it happened I was luckily out with a buddy who suggested I turn the petcock to prime. It started right up and ran happily then. The whole time I would ride I would just leave it on prime. Gas mileage never suffered and no gas ever leaked out of the carbs. BUT I WOULD ALWAYS MAKE DAMNED SURE TO TURN IT TO "ON" OR RESERVE WHEN THE BIKE WAS OFF.

[crc1214]

Oh hey.... another thing you might try is draining the tank to about 1/4 full and take it up to 65 and above with the gas cap off or just loosely on. It could always be a faulty gas cap vent too that's causing this.