I changed out my stock carb with a Super B.&nbsp\\; Great carb and a world of difference.....
There is no problem on regular&nbsp\\;roll-on&nbsp\\;with the throttle, but under snappy or quick throttle, there is spitting and hesitation.&nbsp\\; I am thinking the primary jet is too small for the immediate demand....does this sound right?&nbsp\\; Also, there is a lot of backfiring upon decceleration....maybe the same problem?
Hopefully someone can help out.
Thanks.

 

Backfiring on decel makes me think of an air leak somewhere, without that I'd have agreed on too small an intermediate jet. What intermediate jet are you running? .0295 or larger? Have you already checked for intake leaks?

 

Already check for intake leaks....so far there are none.&nbsp\\; The bands and boots that hold the intake on are about as tight and solid as they can be, as is the gasket between the intake and the carb.&nbsp\\; I have to take out the jet and get the number.&nbsp\\; I am not too familiar with the Super B yet, but I will find where the jet is and pull it to get your opinions.
Thanks

 

IIRC, the B's ran slightly bigger jets than an E on the same engine,with everything else being equal.I've a fairly stock 80cu in shovel (very slight cam) with an E, and am running a .0295 intermediate, and a .074 main. I know I could still go bigger on the intermediate,but&nbsp\\;it doesn't hesitate and&nbsp\\;since this jet&nbsp\\;has the most effect on fuel mileage,I've left it alone.If you have no air leaks, then I'd increase&nbsp\\;the intermediate.The bowl must be removed to do it.The jet will to the side of the center jet (main jet) Brass colored,and longer.Will look like a tube w/screwdriver slot in the bottom.An exhaust leak can cause popping(not&nbsp\\;as much a "backfire" though)sounds from the exhaust too, but this wouldn't effect how well it runs.

 

I'm running a B on mine, without the accelerator pump I don't think you'll ever get the snap throttle response that you're looking for. also check for an air leak at the exaust flanges, when they suck air in, that will make it backfire in the exaust on decel

 

Agree....also that B carb has to be pretty old,the throttle shaft bushings could be worn and leaking air.
They were a good drag racing WOT carb back in the day but there are a lot better carbs made these days,I ran a B on an 86" stroker Iron Sporty years ago that ran like a scalded dog but the carb was never quite street friendly.

 

Thanks for the replies...I just now got to remove the bowl and see the jets.....I have a 72 main and a 31 intermediate. I assume this may be part of thereal problem I am having with the sputtery response and the spitting, etc.
Let me know your opinions on if these are way to small for this FLH running open mufflers. I was thinking of installing power cones at the heads also...any thoughts?
Thanks again

 

The super B has no accl. pump, when you snap open the throttle there is not enough velocity thru the venturi to pull fuel thru the main jet. no amount of jetting is going to stop this.(and still have the bike ride-able) the only thing that I can suggest is don't snap open the throttle "jap bike it"
back fire on decel is always a exhaust leak.(.)