Dyno results

[Drumrguy]

Well, I got my 2005 Ultra Classic getting dyno tuned, I have the 1550 cylinders and pistons, Vance and Hines CNC ported heads, cams, race tuner, the Harley dealer that built it did not dyno it right, after riding on the highway for at least 18 miles and taking an exit and coming to a stop it would stall, also if you were doing 65-70 mph on the highway and let off the gas, when it would hit 2100 rpm it will pop through the exhaust. The guy who is dyno tuning it says he cannot get all the pop out and has done everything he could on the dyno, he is going to look at other things, but he is thinking that it is the Rush slip on mufflers, says I may have to change them possibly, has anyone ever heard of mufflers causing havoc on a bike? Not sure if this is the problem he is going to look at some other things it could be, but this is the 2nd Harley dealer that has said this, just looking for some opinions, please. Thanks in advance.:small3d018:

 

[Hoople]

When you think about what you are doing when you suddenly let off on the gas from cruising RPM, you will see it is almost impossible to get totally rid of popping. No ECM map can react that fast.

You should not get a continuous stream of popping. That you CAN fix with mapping. But a couple of pops until the the off throttle map (declaration enleanment) kicks in is understandable. You will Always get a charge or two of rich exhaust before that map can respond.

Hoop!

 

[Hoople]

Lean condition can also cause popping as will leaks in exhaust.
SO hard to find on the real problem on modded engines

That is true, and that is even harder to fix than it being too rich for a few crank cycles. Getting rid of ALL popping would require almost complete and instantaneous fuel cut off at the moment of throttle release. That is not a function of the Delphi software that I know of. And even then, you will have a rich charge in the pipes for at least 1 good pop.

We don't know if this is a case of a few pops or a Stream of pops.

Hoop!

 

[Drumrguy]

Well, talked to them again today, they got rid of the decell pop, he said it is not popping real loud anymore, he found the problem at the zero throttle position, he said he also tweeked the race tuner for the idle, thought the idle was a little low, I think the problem was the bike was a little too lean at the zero throttle position, so he said it is alot better. On the highway at about 65-70 mph when you let off the throttle and it dropped down to about 2100 rpm it would pop really loud, he said he ran it up to about 80 mph, let off and it came all the way down without the pop, so I feel good about it.