Panhead dies after 5 minutes

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tickface
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Panhead dies after 5 minutes

#1

Post by tickface »

Tearing my hair out on this one, 1951 Panhead with shovel top end, has been running excellent, just ran 500 miles this past weekend. Monday morning it started first kick, got on the highway and it ran great for about 5 miles then starting hesitating and sputtering. Pulled off the highway and it ran okay at low rpm for another 5 miles then died. Looked things over for a few minutes, checked for spark(had it) and it kicked right over but only lasted about another mile, towed it home.

I changed the plugs, adjusted the solids, charged battery(it only took a minute on the trickle charger), rechecked timing, cleaned the carb and checked for loose wires. Bike started a little harder then normal but seemed to be running normal. On my commute today it ran fine on the way in for about 8 miles, then it just died. Pulled over and poked around a bit, turned off my headlight and it started right up and ran good the rest of my commute(25 more mile). When I got to work I turned on the headlight to see what would happen and it sputtered and died.

Left work and it was harder to start then normal, once it started the same things happened, lasted about 8-10 miles and started sputtering and it died. Let it sit for a few minutes, it started right up and ran for 2-3 miles, then the sputtering and dying. This happened another 3 times until I gave up and called for a lift. After waiting for awhile I gave it another shot just for fun and it started right up.
1951 pan-shovel top
Electronic ignition
S&S e carb

Sorry for the book, losing my mind, any help is greatly appreciated.
Cotten
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Re: Panhead dies after 5 minutes

#2

Post by Cotten »

Tickface!

I sounds like you did everything but bubble-test the manifold.

....Cotten
51Hog
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Re: Panhead dies after 5 minutes

#3

Post by 51Hog »

Is the coating on the inside of the tank starting to deteriorate and plugging the fuel line?
Maybe something else in there floating around.
I had a truck that did the same thing. Found that the rubber liner on a fuel line had deteriorated and the inside of the fuel line would collapse causing the engine to starve.
When I would shut it off, the vacuum would release and the fuel bowl would fill the next time I cranked the engine. The line would collapse again, engine would starve etc....
Fuel cap vents plugged?
Dale
RussW
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Re: Panhead dies after 5 minutes

#4

Post by RussW »

Since you said electronic ignition, I assume you have converted to 12V, probably using a sealed AGM battery. These batteries seem to have an odd way of 'dying'; they lose power and the bike dies, then the jump back up to charged and seem fine until you hit the headlights, then they drop again. They may do this "up and down" bit,then finally just discharge and be dead.
Also remember the electronic ignition is much more finicky the voltage levels than points/condenser, I think they need at least 10.5V (?) or they are not happy.
Finally, electronic ignition modules (as in my Mallory) do not necessarily just die as everyone says will happen. I just had to replace mine after 4 years. Became hard to start for a few days, then just quit at a stop light. Pushed it side of road, kicked right over, rode home. Couple days later, idling in driveway while I opened the garage, it just quit. That was it, dead module, but not without a few days warning. Just like the way a condenser went bad with my old points setup, but that time it didn't chose to die in the driveway!
blewcrab
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Re: Panhead dies after 5 minutes

#5

Post by blewcrab »

I put one of those clear glass in line filters on my 65 ..it was located in between jugs ...on my first trip out,she died after 10 or so miles. I could see no gas in the filter..I operated the pingle back and forth a few times and I saw gas flow .she re fired and I got home..I detirmed the pingle was ok .so I removed the in line filter....mabey a vapor lock or something ? but no problem since....just saying
58flh
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Re: Panhead dies after 5 minutes

#6

Post by 58flh »

TICK!----the headlight thing, you shut it off & rode another 25 miles ,turned it on & it spuddered again. Just have a look at the wires going thru into the bucket. I had that same thing happen every time I made a left turn it would spudder or die!, Turn off light no problems, turned out the insul. around the wire worn thru & shoted the dam thing out. worth a look. If you have auto adv. check the springs on the weights.---Richie
tickface
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Re: Panhead dies after 5 minutes

#7

Post by tickface »

Thank you guys for the responses
Richie! Thought of that, actually removed the headlight wire from the switch to completely cross that off the list

Russ-left my voltmeter at work, will check the battery tonight, I'm hoping it is the culprit, it's lasted 3 years so it's probably time for a new one anyway. Interesting about the ignition, it's a Vulcan unit that has been flawless for the last two years. I'm thinking(hoping) it's still good, since I still get spark even when it won't run.

Dale- will check the petcock tonight as well, I don't run any coating as I have never had good experience with any of them.

Cotten! I will bubble test tonight as well, the last time I had the heads off (last summer) I did bubble test it and everything was A O K. Out of curiosity, why do you think an intake leak would result in my symptoms?

Thanks again guys
58flh
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Re: Panhead dies after 5 minutes

#8

Post by 58flh »

IF you do have a leak, As the motor gets hotter it could make a even bigger leak & really give a lean mix in 1 of the cyl.s,---Have your plugs been equal or is 1 white & the other rich running? The extra heat of a leanedout cyl. will open the gap up & fire will not be consistent! When it cools down the gap closes up & spark is as should be!--I have seen lean conditions so bad that there was no ground to ADJ. the gap!--(GONE-melted away).Also at hi-temps the insulaters can crack!--You wont see it but when it get hot ,spudder bang etc. Just my 2 on what I have had to deal with on various bikes over the years.--Hope this helps!---RICHIE :!:
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Re: Panhead dies after 5 minutes

#9

Post by VPH-D »

Is it possible the gas cap is not vented ?
VPH-D
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Re: Panhead dies after 5 minutes

#10

Post by old.wrench »

You might consider checking the coil. I once had a similar problem and tried all the same checks and adjustments that you have to no avail. It turned out to be the coil. As the coil heated up it would temporarily fail. When it cooled down, it would mysteriously work again. Maybe?

Regards,
Geo.
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Re: Panhead dies after 5 minutes

#11

Post by Huck »

Fur ball in the gas tank?
Cotten
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Re: Panhead dies after 5 minutes

#12

Post by Cotten »

tickface wrote: ... why do you think an intake leak would result in my symptoms?....
Tickface!

Because manifold leaks are evil.

Face it, you must eliminate variables, and when everything else is eliminated, you must test the manifold.

Good luck!

...Cotten
PS: Huck!
Its been two weeks since I had a fur ball in my gasline.
tickface
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Re: Panhead dies after 5 minutes

#13

Post by tickface »

Sorry to bring this back up to the top, just wanted to close it out. Found a broken wire in the headlight shell, battery was on its last legs, and the gennie end nut was about to fall off. Fixed the wire, bought new battery, tightened and tested generator, bike runs well again. Thank you for all the input.
ladderguy
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Re: Panhead dies after 5 minutes

#14

Post by ladderguy »

I also had a similar problem with my 52FL. Turned out to be the coil starting to go. Replaced it and no problems since.
Hope this helps
Ladder
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