Bike will not stay started - Alternator?

Andrew Burt

XS650 Special 2
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This morning bike started normal with choke depressed as I waited for it to warm up. But when I opened the choke up and went to leave my garage as soon as I started to accelerate I lost power and it cut out. I went to start again and it seemed like it didn't want to, but I figured it wasn't warm enough. I gave it some more time and ended up jumping it since the battery seemed drained from jumping.

I made it about a mile before it cut out on me again while I was idling on a stop light. Battery seemed drained again so I jumped it again, made it another mile before it cut out again. Only another half mile to work.

Jump again and as I'm pulling in I have no power, barely wants to run in first, I have no acceleration.

When I went to leave work I could get it to start, but it didn't want to idle for more than 30 seconds.

First assumption was maybe the battery, so I took it to autozone and they charged and tested. No issues with the battery. I took it back to the bike, same issues. It would start but wouldn't stay started started, and as soon as I added any throttle it would cut out. Now it seems like I couldn't get the mile that I got this morning even if I wanted to.
 
Well if Auto zone charged the battery you should have been good for 15-20 minutes of running even with NO charging, unless you had to do a lot of cranking to start it.
possibles;
water in gas
plugged fuel filter, screen
air leak.
loose wire
dirty switch contacts
dirt in a carb plugged jet.
troubleshooting 101 time.
 
Ok. So I think I have narrowed it down. Gary was very correct that it wasn't the battery. Looks like the fuel line had a kink in it between the fuel filter and the carb. But I don't think it was the kink causing the problem because it had been there prior, and I rode the bike daily for the last 2 months without any issues.

A question I do have is the fuel line ins't full. I'm not sure if it is supposed to, but it appears the engine wasn't getting enough gas and that is why as soon as I went to throttle up it would die.

I think the issue is with the petcock? When I switched it to prime the fuel line would appear more full, and I could throttle up and ride around in the parking lot without it stalling or issues in the short time I got to test. When I switched it back to ON fuel line looked less full and eventually would stall.

I am ordering a new fuel line so I can have it run without the kink. Also going to get a new fuel filter, doesn't looked clogged, just appears the gas is struggling to get to it.

But would this be a petcock issue? I'm not sure how it works exactly. Is there supposed to be air in the fuel line?
 
Long shot maybe, open the gas cap with the peacock “on” and see if it makes a difference.

Fuel cap open didn't seem to change anything. Still the issues with it set to open. Still the air in the line and still works fine with it set to prime.
 
Gas is funny and not quite as willing to go down hill as we think. Never hurts to clean a petcock,
possible hint; prime is also reserve........... ie it draws from the bottom of the tank not the stand pipe that "on" pulls through. Were it mine I'd have the petcock apart on the bench about now. A kinked line can add to the misery, why the stock lines had springs around them. Trapped air in a fuel line can block flow if it doesn't have a large enough hole to escape upwards. Surface tension acts to prevent the bubble from breaking up into smaller bubbles to pass through narrow passages The petcock can trap an air bubble resulting in very slow fuel flow.
I took this shot long ago and it has always kind of fascinated me, the petcock is open but the fuel is just sitting in the stand pipe, it doesn't run out through the screen, it is NOT plugged either. You can see the top of the fuel it's the curved line up near the top.
82hs 014.jpg
 
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Yeah, like Gary says, clean that petcock. I've seen them so full of HARD crud that they had to be cleaned with a drill bit, spun by hand, before a solvent and compressed air could clean the rest. Smaller diameter filters are often needed instead of large diameter filters to avoid air locks. Like plumbers say, "Shit don't run uphill".

Scott
 
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