Low end hesitation
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Novice
Joined: Oct 2010
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From: Alabama
Low end hesitation
running a '76 fx, S&S Super E with .295 intermediate, 1 3/4 straight drags, electronic ignition. The bike runs great when it's cold, but after running for a while, it has a slight hesitation on the low end ( say, a low rpm pull in 3rd gear). It also sputters a bit if you give a rapid throttle roll from idle (again, only when warm). Carb has been tuned. other than that, bike runs great. any suggestions??
Tourer
Joined: Jun 2008
Posts: 306
Likes: 7
From: Somewhere, PA
In cases like yours, I almost always look for an intake leak - especially because things expand with heat and the small leaks become larger as the bike warms up. Squirting WD-40 or propane around the manifold areas while the bike is running MAY get you lucky, but in many cases this method only catches a large leak. I use a cork or rubber homemade tool that I connect to the carb and put 5-10 lbs of air pressure in her (with the intake valves closed). After you pressurize her, spray soapy water on the carb and intake and she'll start blowing bubbles from the leak spot. I've even seen one guy use a rubber ball that he used to seal the end of the carb and then shot his air through a hole in the ball.
Bottom line, if you have an intake leak and don't fix it you'll waste a lot of time and effort troubleshooting other potential causes...
Bottom line, if you have an intake leak and don't fix it you'll waste a lot of time and effort troubleshooting other potential causes...
Club Member
Joined: Mar 2009
Posts: 66,110
Likes: 51,394
From: Niles Canyon Ca.
Thats an intake leak . If you cannot pin point the problem see below .
Last ditch trick I've had to use on S&S "E" carbs on some shovels with drags is put a 1" spacer block in between the carb & manifold . Some reason shovels with drags like a longer intake draw from the carb . Makes the " E " the same length as the older " B " model and those ran real well with drags . Can't say why it works just does .
PS if you do the intake leak test stay the f*ck away from propane please , use brake clean instead . Idiot did the propane stunt and damn near lobotomized himself when the rear spark plug blew out and bounced off his forehead .
Last ditch trick I've had to use on S&S "E" carbs on some shovels with drags is put a 1" spacer block in between the carb & manifold . Some reason shovels with drags like a longer intake draw from the carb . Makes the " E " the same length as the older " B " model and those ran real well with drags . Can't say why it works just does .
PS if you do the intake leak test stay the f*ck away from propane please , use brake clean instead . Idiot did the propane stunt and damn near lobotomized himself when the rear spark plug blew out and bounced off his forehead .
Last edited by TwiZted Biker; Oct 12, 2010 at 07:45 PM.
Tourer
Joined: Jun 2008
Posts: 306
Likes: 7
From: Somewhere, PA
I've never used propane myself either Twizted, but know of a few who have so I threw it out there. Anymore I just stick with my tool and don't even mess with the local sprays...
Thats an intake leak . If you cannot pin point the problem see below .
Last ditch trick I've had to use on S&S "E" carbs on some shovels with drags is put a 1" spacer block in between the carb & manifold . Some reason shovels with drags like a longer intake draw from the carb . Makes the " E " the same length as the older " B " model and those ran real well with drags . Can't say why it works just does .
PS if you do the intake leak test stay the f*ck away from propane please , use brake clean instead . Idiot did the propane stunt and damn near lobotomized himself when the rear spark plug blew out and bounced off his forehead .
Last ditch trick I've had to use on S&S "E" carbs on some shovels with drags is put a 1" spacer block in between the carb & manifold . Some reason shovels with drags like a longer intake draw from the carb . Makes the " E " the same length as the older " B " model and those ran real well with drags . Can't say why it works just does .
PS if you do the intake leak test stay the f*ck away from propane please , use brake clean instead . Idiot did the propane stunt and damn near lobotomized himself when the rear spark plug blew out and bounced off his forehead .
Club Member
Joined: Mar 2009
Posts: 66,110
Likes: 51,394
From: Niles Canyon Ca.
Using brake cleaner is a no brainer doesn't hurt anything , takes oily crude off for you and the engine will stumble not race up at an idle , just short little burps with the red tube attached .
I don't know where or when the propane thing got started for this test but just sit back and think about it a second , do you really want to spray something that can be very explosive in under a tank with gas in it ?
Road Master
Joined: Jun 2008
Posts: 1,065
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From: Illinois
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Club Member
Joined: Mar 2009
Posts: 66,110
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From: Niles Canyon Ca.
If you have an air cleaner support bracket your going to have to play with it a bit to get things to fit again , another spacer or weld a bit on aside from that just the bolts .
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