Popping on deceleration !!!

[HMAN]

As this has been discussed here before, Ima throw this out there. There was a point in time that S&S posted on their site that a properly tuned S&S carb WILL exhibit decel pop especially with non stock pipes. Their solution has always been....fatten it up to reduce the pop. JMO. I like the pops, as it tends to wake people up from their life induced stupor and causes them to @ least temporarily pay attention.

 

[Sven]

Like I goof on my nephew with his chopper builds... Takes a man to start the bike one kick... Takes a man to live with the pop. It's a chop. It has a small tank. Why would I follow S&S and throw bad mileage at it. Pop out the pipe means nothing but cold meets hot... Thunder Ears!

Pay attention pipes. Bike screams? Starts right up? Idles all day? What's wrong with the bike then?

 

[Pddain]

If it were just the pop I might live with it. The roughness below 2500 RPM is more my concern. I am installing thunder torque lollipops next week and testing. We will then move on to installing a diffuser in the main jet and potentially a 60 in the main air bleed and then open the intermediate drain per S&S We are going to stage this and see what happens. Fun for all.

 

[Jersey Big Mike]

As this has been discussed here before, Ima throw this out there. There was a point in time that S&S posted on their site that a properly tuned S&S carb WILL exhibit decel pop especially with non stock pipes. Their solution has always been....fatten it up to reduce the pop. JMO. I like the pops, as it tends to wake people up from their life induced stupor and causes them to @ least temporarily pay attention.

And as a forum member once told me, "It's a Big Dog -- Let it bark!"

 

[Pddain]

Planned to test ride today, but it rained. Dan re-worked the carb so performance in the 2500 RPM range should improve. If this does not solve the decel issue we will work the back pressure to get it cleaned up, I hope. More concerned with the roughness and popping at 2500 RPM, but since we are working on it anyway, we are going to just how much we can reduce the popping with increased back pressure. On the V&H pipes, the Lolly pops are not feasible.

 

[COOPer]

I put those lolly pops in was sort of a pain to get them in tha far but did it and it didnt make any difference

 

[Pddain]

Thanks. We are going to work with the existing baffles and modify them to get the correct back pressure. I think we are close, but need to test ride to see where we are. Will let y’all know in the next week

 

[Mickmorris]

Thanks. We are going to work with the existing baffles and modify them to get the correct back pressure. I think we are close, but need to test ride to see where we are. Will let y’all know in the next week

Sounds like you have a great plan Paul. Pretty sure you will have it running & sounding the way you expect it to soon.

 

[Sven]

I put those lolly pops in was sort of a pain to get them in tha far but did it and it didnt make any difference

What HMAN said. Air screw on the air cleaner side is for air. Shut the air off, more fuel at the lower rpm range. Screw past the throttle slide and between head, this is fuel. So say a 1/4 out to go rich, angle the lollypop at a 45 degree, or 90 and find that breakup angle at some degree point? That, or a needle set higher, clip set lower and that exposes more lift goes rich when the slide closes, and the pop gets a little rich sent at it.

 

[Pddain]

Thanks Sven. Working it. Will let you know.

 

[Pddain]

Ok, probably the last installment. Recapping, I had a rough running engine between 2000 and 3000 RPMS with severe decel popping any time I let off the throttle even slightly. the bike felt like it was running out of gas when trying to cruise below 30 (2300 to 2800 RPM). The throttle was very sensitive and difficult to control

I followed the S&S recommendation on jetting and put a 60 in the main jet air bleed. My mechanic put a screen on the intermediate jet to atomize the fuel. We then added lollipops to increase back pressure and increase exhaust gas speed. We did not remove the intermediate bowl vent plug, as recommended however.

Results
The throttle is very responsive but smooth through the entire range. Cruise in the 2000 to 3000 RPM range is smooth and comfortable, jerking is gone. Decel popping is dramatically reduced, vibration has reduced significantly. With V&H 2 inch, 2 into 2 short pipes and a cone air cleaner, the decel popping won’t go away, based on my research, but the bike runs great, and the barking is minimal. There is a felt increase in torque but a Dyno is not in my current budget.

thank you all for the guidance. You are all the best.

 

[Jersey Big Mike]

Ok, probably the last installment. Recapping, I had a rough running engine between 2000 and 3000 RPMS with severe decel popping any time I let off the throttle even slightly. the bike felt like it was running out of gas when trying to cruise below 30 (2300 to 2800 RPM). The throttle was very sensitive and difficult to control

I followed the S&S recommendation on jetting and put a 60 in the main jet air bleed. My mechanic put a screen on the intermediate jet to atomize the fuel. We then added lollipops to increase back pressure and increase exhaust gas speed. We did not remove the intermediate bowl vent plug, as recommended however.

Results
The throttle is very responsive but smooth through the entire range. Cruise in the 2000 to 3000 RPM range is smooth and comfortable, jerking is gone. Decel popping is dramatically reduced, vibration has reduced significantly. With V&H 2 inch, 2 into 2 short pipes and a cone air cleaner, the decel popping won’t go away, based on my research, but the bike runs great, and the barking is minimal. There is a felt increase in torque but a Dyno is not in my current budget.

thank you all for the guidance. You are all the best.

Glad to hear you got it where you are happy with it.