by LRM » Sat Feb 29, 2020 7:56 am
What you are describing is ALL jetting, not compression. But I suggest either using the JD Kit or the another choice and sticking with it until you get it sorted out. Your comments are indicating that you put it in try it and then change the set up without solving the tuning issues.
I had the exact same issue with my XT. I consulted Kels and JD, I gave you the set up from Kels already and this is the advice from JD;
"The off-idle is leaner with the red needle vs blue, but the tapers are the same in this jet kit's needle set. As a result, I was suggesting a richer tapered part using the #3 clip on red instead of #2 on blue. The air screw would probably need richening to keep the off-idle from being lean"
Quote from your post; "the blue needle in #3 is very smooth but the pipe bang is the worst of any needle I’ve tried." for above coment.
Either of these two jetting combo's will stop your pipe bang, just like they did mine. But the A/S is the final factor in the tuning to stop it. Don't be afraid to open it up if you need to. I'm running the Kels jetting I gave you and my A/S is 3.5 turns open. But both bike will start and set and Idle as they run out of gas. NO pipe bang on decel, with either one.
I would like to know if your RK Tek head was purchased used or straight from Kels? When you purchase one straight from Kels , he always ask you what fuel, elevation FUEL and mods you deal with. If you got it from Kels, what ever you told him at that time ab out fuel use is what you need to stay with. If you got it used , I would never run less than 91 octane.
I hope this help you solve your Pipe bang.
The only time you need he 2nd Amendment, is when someone comes to take I away!