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Discussion Starter #1
My other scoot is a Big Dog Mastiff and I hope it's ok to ask for some help. It has an S&S 117 with S&S Super G Carb. My bike runs fine on a full tank of gas but after exactly 65 miles it acts as if it has vapor lock and hesitates on acceleration. I know it's not vapor lock because I have a vented gas cap and I've removed the fuel line (at the carb) and the gas flows fine. At 70 miles, the bike completely stalls. Sometimes I can restart it and other times I have to push it to a gas station. I have a 4 gallon tank and there's always at least 2 1/2 gallons left in the tank after it happens. I would appreciate any advise or insights. Thanks in advance.
 

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Is there a filter on the line? Have you tried changing out your fuel line? Sounds like something is plugged, and only with a full tank of gas is there enough static pressure to force the fuel out. That would be my guess. You might also take your tank off, remove your petcock and make sure it flows fine from there. Id definatly replace your filter if you haven't already,.. then might as well change the fuel lines while your there.
One more thing.. it could still be your cap with the vent plugged. Ive read on chopper forums of guys replacing the caps and the bike ran fine.
I got a buddy in town that rides a Big Dog (can't remember, it may be a ridgeback) and he is always playing hell with clutches and transmissions. The 117 is a strong motor, that sucker runs good.
 

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Discussion Starter #3
Is there a filter on the line? Have you tried changing out your fuel line? Sounds like something is plugged, and only with a full tank of gas is there enough static pressure to force the fuel out. That would be my guess. You might also take your tank off, remove your petcock and make sure it flows fine from there. Id definatly replace your filter if you haven't already,.. then might as well change the fuel lines while your there.
One more thing.. it could still be your cap with the vent plugged. Ive read on chopper forums of guys replacing the caps and the bike ran fine.
I got a buddy in town that rides a Big Dog (can't remember, it may be a ridgeback) and he is always playing hell with clutches and transmissions. The 117 is a strong motor, that sucker runs good.
I haven't changed the filter but that's at the top of my list. My fuel lines appear fine. I've removed the fuel line at the carb and the gas flows fine. I have 2 vented caps and I've alternated just in case one is not breathing properly. This has been my problem... I've already tried everything I can think of. It was suggested that my fuel tank liner may have come loose. I'm checking it out over the weekend and I'll check the gas filter at the same time. My Big Dog is a cool bike but hardly reliable. Many people complain about clutch and transmission problems. I've thought of putting a Harley transmission on the bike and ditching the Baker tranny. The other big problem is the EHC and all of the electronics. Wire Plus sells a great wire harness to replace the EHC but it will set me back about $600.00. Thanks for the advise.
 

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Just a thought - I don't remember it all but in a recent (6-9 months) AI Mag article a guy had the same problem and the cure was something to do with the tank having two cells in it and the gas not flowing back and forth or the fuel pump wasn't picking it up at speed...but then I've got CRS.
 

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Discussion Starter #5
Thanks Joke. I'm checking everything possible. Another thought is that it's my carb. If the gas is flowing freely through the fuel line perhaps the problem is in the carb. Hmmmm?
 

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Thanks Joke. I'm checking everything possible. Another thought is that it's my carb. If the gas is flowing freely through the fuel line perhaps the problem is in the carb. Hmmmm?
After you go through all the obvious items above, if it still gives you grief check the float needle and seat, you might have a sticky seat and as Chain said "static pressure" may be allowing fuel past until certain point and then it shuts off.
 

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Discussion Starter #7
After a stall, I've tried jiggling my fuel line and pinching it to create a vacuum. It hasn't helped. I'm going to try everything obvious first, however, I'm beginning to think the problem lies after the fuel line hits the carb. Again, I'm a novice mechanic but my common sense is telling me that the fuel flow is fine so the problem must be elsewhere. Also, I just realized something; I should try switching the tank to the reserve once the problem happens. Depending on what happens, it may tell me a lot about what's going on. I should have thought of this a long time ago... duh!
 

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After you go through all the obvious items above, if it still gives you grief check the float needle and seat, you might have a sticky seat and as Chain said "static pressure" may be allowing fuel past until certain point and then it shuts off.
Not sure if static pressure was the right word.. ;) Thats just the oilfield in me talking and the only way I knew how to describe it
 

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Not sure if static pressure was the right word.. ;) Thats just the oilfield in me talking and the only way I knew how to describe it
Sounded right to me!
 

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Discussion Starter #10
JUST WANTED TO GIVE AN UPDATE. I SOLVED MY PROBLEM. I DECIDED TO REMOVE THE PECTOCK AND SEE IF ANYTHING STRANGE WAS HAPPENING. THE FUEL SCREEN WAS COVERED IN GREEN PAINT FROM MY TANK LINER. I REMOVED MOST OF THE PAINT BEFORE I TOOK THE PHOTO BUT YOU CAN SEE A LOT OF IT AT THE BASE. THIS IS COVERED UNDER MY WARRANTY BUT I'M GUESSING THAT I'LL BE WITHOUT MY BIKE FOR AT LEAST A MONTH.

 

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Glad you found the problem.

I was going to suggest to open your drain screw when it stopped and work back from there.
 
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