S&S Super B with a popping problem

S&S carburetor isues
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52EL

S&S Super B with a popping problem

#1

Post by 52EL » Fri Jan 23, 2009 2:38 pm

I have a 52pan with a popping problem. First the top end has been redone to .040 over recently. the timing and circut breaker gap is on the money. It starts easy enough, but when it fires i have to shut the enhancer down immediatly or it will foul the plugs. It will idle fine and after it is warmed up it has good power through first and second gear. When you hit third it pop back through the carb when you go to fourth it calms down but every now and then it will pop. I'm leaning towards an air leak in the throttle shaft or possibly a intermidiate re jetting to next larger size. any ideas? I have checked the manifold and feel confident there is no leak there I sprayed carb cleaner around the seal and also into the throttle bushing but the engine does not change rpm's regardless i think i should redo the carb with a rebuild kit i have no knowledge of its past and i couldn't hurt. thanks for any info .......52EL

Post by Sidecar on Oct 16, 2003, 4:19pm

I had a similar "popping" problem stuffing too much fuel into the bike, in the mid range, with an E. It would happen when upshifting into 3rd and 4th.
I think you have some other problems though.
Bring on the carb guru !!!!I'm not a S&S Super B guru, but....

Post by Cotten on Oct 18, 2003, 12:34pm

I used to run a B many years ago, but don't consider myself an expert on them. (I do vintage units for a living.)
Frankly, I don't think much of barnyard carbcleaner leak testing. You could still have a manifold leak, as a tiny one could result in your popping, yet escape the douche.
Get a big cork and try pressuretesting the manifold at ~12psi and squirt diluted dishsoap around anything that might leak. I have even found leaks up through pancover screws like that! Pay particular attention to your nipples into the heads themselves, and their rivets, as early pans are prone to problems there. If you have an o-ring update, it is almost certain.

Here's more involved suggestions: http://virtualindian.org/11techleaktest.html
Bubbles will tell you where and how much of a problem there might be, and even find pinholes in welds and castings.
At least if it is sealed, then you can be certain that it is in your carb. Unless the points are bouncing. Or you might even have an electrical connection that vibrates at just that particular speed and RPM. (I had a dashcover that would blow fuses only when I used a particular interstate on-ramp....)



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Re: S&S Super B with a popping problem

#2

Post by 58flh » Tue Nov 08, 2011 2:23 pm

52EL wrote:I have a 52pan with a popping problem. First the top end has been redone to .040 over recently. the timing and circut breaker gap is on the money. It starts easy enough, but when it fires i have to shut the enhancer down immediatly or it will foul the plugs. It will idle fine and after it is warmed up it has good power through first and second gear. When you hit third it pop back through the carb when you go to fourth it calms down but every now and then it will pop. I'm leaning towards an air leak in the throttle shaft or possibly a intermidiate re jetting to next larger size. any ideas? I have checked the manifold and feel confident there is no leak there I sprayed carb cleaner around the seal and also into the throttle bushing but the engine does not change rpm's regardless i think i should redo the carb with a rebuild kit i have no knowledge of its past and i couldn't hurt. thanks for any info .......52EL

Post by Sidecar on Oct 16, 2003, 4:19pm

I had a similar "popping" problem stuffing too much fuel into the bike, in the mid range, with an E. It would happen when upshifting into 3rd and 4th.
I think you have some other problems though.
Bring on the carb guru !!!!I'm not a S&S Super B guru, but....

Post by Cotten on Oct 18, 2003, 12:34pm

I used to run a B many years ago, but don't consider myself an expert on them. (I do vintage units for a living.)
Frankly, I don't think much of barnyard carbcleaner leak testing. You could still have a manifold leak, as a tiny one could result in your popping, yet escape the douche.
Get a big cork and try pressuretesting the manifold at ~12psi and squirt diluted dishsoap around anything that might leak. I have even found leaks up through pancover screws like that! Pay particular attention to your nipples into the heads themselves, and their rivets, as early pans are prone to problems there. If you have an o-ring update, it is almost certain.

Here's more involved suggestions: http://virtualindian.org/11techleaktest.html
Bubbles will tell you where and how much of a problem there might be, and even find pinholes in welds and castings.
At least if it is sealed, then you can be certain that it is in your carb. Unless the points are bouncing. Or you might even have an electrical connection that vibrates at just that particular speed and RPM. (I had a dashcover that would blow fuses only when I used a particular interstate on-ramp....)
58flh---the S&S B carb. is a very sinple carb. NO parts, just float & seat set-up & jets,bowl,&Enrichening valve, throttle-fly! --Your problem is definetly not a jetsize! ,It sounds more like a vacuum-leak ,I have seen one spudder through, get this the bowl gasket! not a good seal between bowl & carb. That was a brain buster because he put on a new gasket, then when I pulled the gasket the mating surface had a divit in it. It would start good idle good run good but at that 3rd gear rpm it spudder like not enuff fuel--it was to much air leaning it out!-Im not saying you have the same prob. But check for those elusive vacuum leaks & make sure nobody mashed the ADJ. screw in real tight against the seat! Also remember the B has no accelerator pump ,so if you wack it at that 3rd gear shift--its gonna spudder!-(GOOD-LUCK).

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