Panhead stops during run.

[gosilver]

Hello to all,
I'm still in the phase of "ask." I hope tomorrow I can get in the "give" one.
Facts: my pan stops when runs. This does not happen with a specific condition. The first time it stopped after a few meters, it seems like there was no gas in the line. I get down the bike, a kick, and she starts. Another 200-300 meters and stop again. This sequence every 400-500-600 meters. Back in the box I disassembled the fuel line, and I blew into it. I disassembled the carburetor to see if there was dirt in the tub and in the float. I cleaned everything but seemed fine. I tried again and seems the problem was solved (but I made a short run being night). Saturday I run again the bike, and she did again the defect. No power, I speed on and off (except the last time, waving at the roadside, I was able to keep her alive by modulating somehow the gas - but I think it was just a combination -). I started to run and I tried to go fast to see if I had the power deficit. The bike ran great in every gear and no defect. I'm back in the box and checked the float again (clean) and gas lines (in order). I disassembled the candles and were dry and a bit dirty (I run rich and the sparks are "normal" but I brushed them anyway), I checked the cable connections to the battery and the ignition switch (although I have on a "modern" one that should not have contact defect). Now ... from what I start to do other controls? I fear (because I' am more ignorant than in mechanics) that the problem is electrical. The bike is a '49 Fl. I still have the automatic advance (I'm lazy and I do not put the manual when I bought it). I have an electronic cut out realy. Electric system is 6 volts. The generator (32E) has three brushes, and good charge (the measured battery gives 6.7 volts at 2000 rpm). Particular is the fact that when the bike stops all the lights are bright and at the first kick she starts without problems. It could be a wire? the coil? or something else? where do I start?
Thank you all.
(sorry for my bad English)

[kfelt]

Do you have a rubber tipped float valve? Sometimes the tip can come off and plug the hole temporarily. Happened to me once. Replaced it with a stainless one.

[gosilver]

Do you have a rubber tipped float valve? Sometimes the tip can come off and plug the hole temporarily. Happened to me once. Replaced it with a stainless one.

thank you.
No, I've got a stainless steel one.

[hogboy52]

Is the fuel line routed in a manner where it can trap air? If so it will not feed the carb well.

[gosilver]

Is the fuel line routed in a manner where it can trap air? If so it will not feed the carb well.

Thank you.
No, because when I disinstall the fuel (stock circuit) line from the carb, I've seen (and tested) the amount of fuel coming out, and it was right.

[Dave_R]

Had Similar symptoms. The fuel cap vent was plugged. May want to check there. Try it with the cap loose to isolate.
Just another idea.
Thanks - Dave

[gosilver]

Had Similar symptoms. The fuel cap vent was plugged. May want to check there. Try it with the cap loose to isolate.
Just another idea.
Thanks - Dave

Thank you Dave.
I've blow into the fuel cap...and it was ok. I've tried to run without cap...no way...the bike stops.

[RUBONE]

I've tried to run without cap...no way...the bike stops.

Well if that is the case you are getting closer to your problem. The bike should run just fine without caps. If it dies it has a fuel flow issue and pressure buildup in the tanks is forcing it to flow somewhat. Everything upstream of the carb needs to be checked for blockage.

[PanPal]

a lot of good suggestions so far. Never trusted the aftermarket ignition switches? coil bad? If you vapor lock and go check the gas line it may flow fine when you take it off. Do you have a rubber gas hose running between the cylinders that could be heating up on you?

[59Panman]

Are you running a Linkert? If so, what type of float is in it? The float should also be aligned off center slightly so it does not rub on the bowl. Did you check the fuel line screen for any debris? You state no gas in the line.

If you don't have a Liberty Float, I would order one from Liberty Cycles.

[Wrong Road]

I have had this happen to me on my shovelhead. I bought new fuel line that turned out to be too soft. As soon as the motor warmed up, the fuel line would soften and collapse. No fuel could get to the carb. Get some rigid or metal fuel line.

[Andygears]

How bout electrical? Take the cap off the circuit breaker, try in the dark, so you can see the points spark, when it quits, use a screwdriver to open the points/ or short 'em. Without moving anything! When it quit you stated it immediately would refire. But immediately is flopped back on the kickstand and wound back up for a jolt on starter pedal. I'm thinking a loose wire or terminal on the post inside bottom of the circuit breaker. It vibrates, shorts, kills the bike, flop on stand, kick, restarts cause loose wire settled down.

Another idea in the same vein, kill button on handlebar? Try disconnecting entirely.

Or sometimes a coil will quit when it gets hot, then later more inconsistent.

My 2 cents, good luck

Andygears

[gosilver]

I've tried to run without cap...no way...the bike stops.

Well if that is the case you are getting closer to your problem. The bike should run just fine without caps. If it dies it has a fuel flow issue and pressure buildup in the tanks is forcing it to flow somewhat. Everything upstream of the carb needs to be checked for blockage.

Thank you Rubone.
Ok, is a possibility but...when I disinstall the fuel line to the carb (not from the tank, and before I blow it with compressed air) I tested it opening the shut off valve. The amount of fuel flowing seems right. Strange think is that when bike stops, quickly i get down, i give a kick and she starts immediatly. If there is no sufficient fuel to make run the engine....is possible that in, boh, four-five second, the amount of fuel become right to start the bike at first kick without missing too if I open the throttle?

[gosilver]

@Panpal
thank you, but the fuel lines are metallic.

@Ozwick
yes, i'm running with a linkert and the float is mettallic and correctly in site as you say.

@wrong road
sorry, but my fuel lines are metallic...so non deformation is possible.

[gosilver]

How bout electrical? Take the cap off the circuit breaker, try in the dark, so you can see the points spark, when it quits, use a screwdriver to open the points/ or short 'em. Without moving anything! When it quit you stated it immediately would refire. But immediately is flopped back on the kickstand and wound back up for a jolt on starter pedal. I'm thinking a loose wire or terminal on the post inside bottom of the circuit breaker. It vibrates, shorts, kills the bike, flop on stand, kick, restarts cause loose wire settled down.

Another idea in the same vein, kill button on handlebar? Try disconnecting entirely.

Or sometimes a coil will quit when it gets hot, then later more inconsistent.

My 2 cents, good luck

Andygears

thank you Andy,
I'll try to do this experiment you say. I've checked the circuit braker but superfically. I'll try to do in the dark and make the operation you say.
I dont have a kill button on handlebar, only the switch on the dash.
about the coil...the trouble seems more frequently when bike is cold (cold, for me, indicate the first 15 minutes of use)
I'll think i'll need luck.