Update: Decel Pop Exhaust

[Deye76]

Got a new S&S G and installed it last night. I put the same size jets that came in the R1 on my Ultima 113. Ran it about a hour and half at varying speeds/traffic conditions, no decel popping, except a little at 4 grand + from wide open to shut, in the lower gears, none around town like before. Throttle response very good. Still adjusting mix,  a little rich, but in these colder temps, not concerned.  Dyno tune when I find someone who can tune carbs. Appreciate those here who gave advice.

[Racepres]

Carb tuning is Not rocket science... start at Idle and work up... No Accelerator pump.. or you will Never get there...

[Deye76]

Carb tuning is Not rocket science... start at Idle and work up... No Accelerator pump.. or you will Never get there...

So why I am I not concerned it's a little rich?

[Racepres]

Carb tuning is Not rocket science... start at Idle and work up... No Accelerator pump.. or you will Never get there...

So why I am I not concerned it's a little rich?

I don't know... are you using the accelerator Pump???

[Deye76]

I thought tuning was not rocket science. 
It's because air is more dense in colder ambient temps, hence the mixture is leaner than in warmer temps.
Still haven't answered my question about how many R1's you've worked on.

[Racepres]

I thought tuning was not rocket science. 
It's because air is more dense in colder ambient temps, hence the mixture is leaner than in warmer temps.
Still haven't answered my question about how many R1's you've worked on.

Honestly... I wouldn't walk accross the street for One... but have tried to help with them... how I got my attitude about them!! Now S&S... different Story.. In fact I was Sponsored by S&S back when we had a race team..
I even still have an Experimental one.. And... No I do Not need a Dyno to tune for conditions!!
Not even when we went from Atlanta to Denver!!!

[Deye76]

"I was Sponsored by S&S"
For advertisement, or tuning prowess? 

[Racepres]

"I was Sponsored by S&S"
For advertisement, or tuning prowess? 

IDK.... set more than a Couple National Records tho... so Prolly Advertising!!!

[Deye76]

 

[Burnout]

Got a new S&S G and installed it last night. I put the same size jets that came in the R1 on my Ultima 113. Ran it about a hour and half at varying speeds/traffic conditions, no decel popping, except a little at 4 grand + from wide open to shut, in the lower gears, none around town like before. Throttle response very good. Still adjusting mix,  a little rich, but in these colder temps, not concerned.  Dyno tune when I find someone who can tune carbs. Appreciate those here who gave advice.

A "little rich" is why it is not decell popping, when it is rich you will get an orange flame and a "bloop" when the mix is better you will get blue flames and crackle and pop. The reversion draws air into the pipe and the unburned fuel lights off. When it is rich it is a lazy burn, when the fuel mix is cleaner it will burn fast with a pop. When you close the throttle you instantly shut off the air but there is still fuel in the motor. The overrun causes very high vacuum which draws more more fuel thru the idle circuit, since the throttle is closed. That fuel winds up in the exhaust because it is too rich to burn in the cylinders, it then burns in the exhaust.

This is an easy fix with fuel injection as you can turn off the fuel on decell. With a carb you live with it or install mufflers. Stop the reversion and you will stop the pop, it can't burn fast without the oxygen brought in by the reversion.
Throw this all in the dumpster if you have any exhaust leaks. Exhaust leaks magnify this issue x10.

[Racepres]

Got a new S&S G and installed it last night. I put the same size jets that came in the R1 on my Ultima 113. Ran it about a hour and half at varying speeds/traffic conditions, no decel popping, except a little at 4 grand + from wide open to shut, in the lower gears, none around town like before. Throttle response very good. Still adjusting mix,  a little rich, but in these colder temps, not concerned.  Dyno tune when I find someone who can tune carbs. Appreciate those here who gave advice.

A "little rich" is why it is not decell popping, when it is rich you will get an orange flame and a "bloop" when the mix is better you will get blue flames and crackle and pop. The reversion draws air into the pipe and the unburned fuel lights off. When it is rich it is a lazy burn, when the fuel mix is cleaner it will burn fast with a pop. When you close the throttle you instantly shut off the air but there is still fuel in the motor. The overrun causes very high vacuum which draws more more fuel thru the idle circuit, since the throttle is closed. That fuel winds up in the exhaust because it is too rich to burn in the cylinders, it then burns in the exhaust.

This is an easy fix with fuel injection as you can turn off the fuel on decell. With a carb you live with it or install mufflers. Stop the reversion and you will stop the pop, it can't burn fast without the oxygen brought in by the reversion.
Throw this all in the dumpster if you have any exhaust leaks. Exhaust leaks magnify this issue x10.

I did Not get the memo that we were Not dealing with a real Exhaust system...You are correct on all accounts...excepting some can eliminate the reflective [reversion] wave with a Reversion Trap even without Mufflers...
But, some bit of time, and for me, trial and error, is required to get the Reversion dams and traps in the right place... Which is not as close to the port as some Snake Oil fixes!!!

[Deye76]

Thanks for explanation Burnout, I'll leave it a little rich not to have to put up with the pop. With the R1 it was little fat, but ran good, and I suspect better with the S&S. Plugs never looked sooty (if that's a word LOL) and with several oil analysis,  no fuel detected.

"I did Not get the memo that we were Not dealing with a real Exhaust system."

Had no idea a Bassani was not a "real exhaust". 

[Racepres]

Thanks for explanation Burnout, I'll leave it a little rich not to have to put up with the pop. With the R1 it was little fat, but ran good, and I suspect better with the S&S. Plugs never looked sooty (if that's a word LOL) and with several oil analysis,  no fuel detected.

"I did Not get the memo that we were Not dealing with a real Exhaust system."

Had no idea a Bassani was not a "real exhaust". 

Depends.... Baffles in or just empty straight pipes??
The Bassani I have is about the loudest SOB I ever ran from any source... except Drags... which are Not a real Exhaust... no matter who made 'em!!