1980 Cuts out at high speeds

[XSBIlly]

Im having trouble with my bike at high speeds, I took it down the highway yesterday and got up to around 75-80mph, and it started to cut in and out and eventually died. It took a little while but I got it started again and rode it around my neighborhood for about an hour never getting above 45mgh with no problems.

Any thoughts?

 

[jamesgs4]

jetted too lean maybe? float levels too low? got any mods?

 

[XSBIlly]

No engine mods

 

[TwoJugs]

Sound like a fuel issue. Try making it happen again and before you start it open the bowl drains and see if they are dry, low or empty?

 

[XSBIlly]

Ill give it a try, the next time I can get to it will be tuesday. What should I do if I look and the bowls are empty?

 

[TwoJugs]

Could be a fuel restriction, clogged filter(s) or screen in tank petcock. If both are equally low or empty I would not rush into the float s but you might need to go there eventually. Did you ever have it running right at this speed before? Shut off the petcock as soon as it dies or the bowls might fill again before you get the chance to inspect the bowls.

 

[XSBIlly]

No, I have been riding it around the city with no problems for a couple months. I first had a problem with it when i was riding it from the city to my parents house about 40 minutes away. My mechanic found some bare wires that shorted out one of the fuses when I was riding it back from the shop I got it up to about 70mph it started cutting in and out and eventually died. But like i said before I ran it for about an hour at lower speeds with no problem.

And I always seem to have fuel running from the petcock with no problem.

What are the chances of the jets being partially clogged and not getting enough fuel at higher speeds?

 

[jamesgs4]

It is worth checking out, cleaning them wont hurt. and while you are there, step up your jets one size.

 

[XSLeo]

Gas tank vent plugged. At lower speeds the gas flows fast enough, at higher speeds air can't get in as fast, no air in, no gas out.

 

[XSBIlly]

How do I know what size to go to? Im guessing they are stock

 

[jamesgs4]

Good thinking Leo!
billy pop your cap a little and do a high speed run to test what leo said. drain your tank to about 1/4 first though, you dont want to end up like MJ.

 

[XSBIlly]

Ill give that a try too, Im defiantly gonna re jet though. Ill be back next week to let you know if that "fixes" the problem.

 

[XSBIlly]

My jets didnt come in time, but I did do a high speed test with the fuel cap open to no avail! Also I pulled the tank for paint. So I will resurrect this thread once I get it rejetted and put back together.