Just got my bike back and breaking in the engine. Having issues with what I guess is pretty common with a Super E. After climbing a small hill or rise at low throttle I get a sneeze through the carb when backing off. This is all new.
Installed S&S top end kit (pistons, jugs, heads), Sifton 112 (Black Widow Cams).
CAlled S&S and must have caught them at a good time and the recommended drilling out the main jet air bleed to approx .055 - .062.
My question for anyone who has done this is how deep should I go with the drill?
From the symtoms I would look for a vacuum leak from the intake. If anyone was in the carb, make sure the o-ring is on the accelerator pump nozzle. Drilling the main jet air bleed delays the rpm when the main jet provides fuel in the 3000 to 3500 rpm range as the intermediate jet is tapering off then and the mixture can be too rich with both jets metering fuel at that rpm. Drilling the main jet air bleed won't cure the problem you're having.
Thanks, I will check the o-ring. The guy that did the work did change the intermediate jet up one.
Will running without o-ring cause that lean sneeze when backing off throttle. The bike does not exhibit any signs of a vacuum leak. Idle is dead stable and comes right down when stopping bike.
I pulled the float bowl yesterday and o-ring was in place. I look up and surprised to find a main air bleed jet. I swapped up to a 74 main jet and installed the smallest main jet I had to replace the air bleed. Air bleed jet is now a 62. I was not prepared for how the bike runs. Fantastic!
Quote from: waltcentral on October 05, 2020, 07:43:33 AM
I pulled the float bowl yesterday and o-ring was in place. I look up and surprised to find a main air bleed jet. I swapped up to a 74 main jet and installed the smallest main jet I had to replace the air bleed. Air bleed jet is now a 62. I was not prepared for how the bike runs. Fantastic!
Good Job! I guess I don't know "Potty mouth", Ha!
When talking to S&S I questioned the advice also. It did not make sense to me either.
What was the sizes of the main jet and air bleeed jet you replaced for the 74 main and 62 air?
S&S 80 top end kit?
replaced 72 main with 74, standard 40 air bleed jet with 62, i may go back to 295 intermediate.
Yes S&S 80" top end kit 8:1 compression.
If ever Thunderjet equipped, that air bleed is moved/machined externally and a Mikuni main jet is used, and then the 3rd circuit of the T/jet is also available for tuning then as well.
That's not necessary with a 2004 and later E or G Carb. They have a replaceable internal air bleed jet. In these standard S&S main jets were used.
I wonder why the earlier Thunderjet conversion moved the Mikuni jets to the outside of the carb. One should think they would have done an acceptable job from the inside?
Perhaps because there was a drilled hole on the side of the carb for a fixed air bleed. At least that is how the B works.
-JW
Quote from: xlfan on October 20, 2020, 06:36:55 AM
That's not necessary with a 2004 and later E or G Carb. They have a replaceable internal air bleed jet. In these standard S&S main jets were used.
I wonder why the earlier Thunderjet conversion moved the Mikuni jets to the outside of the carb. One should think they would have done an acceptable job from the inside?
Ease of tuning and the many sizes available.
Thunderjetted B, E, G, D, carbs work VERY WELL in the hands of a good tuner. :up:
Maybe it's just me, but when we decades ago, added the air bleed adjustability circuit to the s&s carbs, I didn't like the exposure of the float chamber to the elements. I actually cut out a piece of a beer can to bend over and cover the Mikuni jets opening.
I guess no issue for a race bike or a California bike, but for daily drivers that see rain when parked, I didn't like it.
No issues whatsoever here, or reported back to us over the past 20 plus years of installing literally hundreds of them, in regards any debris getting into that air passage.