But how's your actual drivability?...you know, throttle response, any cruise surging, etc. On your decel popping, I've seen that occur both ways...lean and rich. Also, something that happened to me on my May Utah trip was a little bit of a surprise. I've had decel popping for some time will all other performance parameters just about ideal. While in Utah during a post ride bolt-check session back in camp, I felt a little wiggle in the head pipe. The exhaust flange was a little loose. I back it out and looked at the gasket, it had eroded badly. I tightened everything up, and it was fine for the rest of trip. A new gasket fully finished the repair back home. I'm not saying this is your decel popping issue...just something else to check.

 

Damn good questions....

Power is good, throttle response ok with some surging at steady rpm.im going to classify my "popping" as sharp cracks... I've changed header gasket, tightened it up, sealed joints, same result...

Oh, and forgot to mention it's hard to start warm....

I'm just shooting from the hip right about now.... I just dropped the needle to the 4th notch down, see if it makes a difference...if not enough, I'll change to a p6 and 132.5 main.

When I went to the 351, I changed plugs... The difference in color between the two is dramatic... Old One is a nice and dark and new one is white...

Oh, and thanks for helping me trouble shoot this....

 

So took her for a short ride with 4th notch... power is the same as far as I can tell, didn't crank her because of wet, cold roads..

Backfire has been downgraded from a Constant sharp cracking on deceleration to a very light occasional pop...happy with that!

Header temp, using a temp gun, is noticeably lower, hard to tell accurately, because it's chilly out, but I'm guessing 40 degrees lower...at least doesn't seem to glow

Now should I go ahead with the p6 and 132.5?

 

Until temps get up a bit to where you can actually ride it like you normally would, drivability is going to be hard to assess. You want the carb jetting as reasonably lean as you can get but where drivability is still solid...no hesitations, no detonation, and no surging. It keeps your fuel mileage more optimum and less carbon buildup in the top end. Might be better to wait until you can get some real world driving with the needle adjustment you just performed.

 

FWIW Header glow covered in a VitalMX thread:



Ryan Villopoto sitting ready to ride. Gotta believe they have their jetting closer than most any average joe does. If the idle adjustment is done correctly (if the screw is opened too far the idle drops, if the screw is closed too far idle drops, set the screw mid-way between) the idle is not rich or lean - pipe will still glow if not moving for several minutes. That's what happens when there is no air flow over a four stroke exhaust.