I have an HMF sliip-on and I have noticed that there is a difference if you run with or without the spark arrester. When on, it seems to have a better low-mid, then chokes on top. Without it, it softens the power on the bottom, but mid-top is improved. Is this normal? Or do I have to re-jet when taking the arrester off to improve low end power?
BTW, my jetting is 170 main (mikuni), needle in 4th, pilot 4 turns out, and oldman's carb mods, at 3000ft.
Thanks

 

I run the HMF sport slip on, and the screen spark arrester makes no differences on mine. If I use the Quite Core that is spark arrested, then it does cut some of the power down. If it is just a spark arrester screen that your are putting in, I cannot imagin it making a noticable difference.

 

I really dont think you should have to rejet with just the screen in. To get perfect jetting you should, but I doubt you would even notice.

I did notice the few times I tried messing with my quiet core that it really killed power. I tried rejetting and just couldnt get much of the power back. If you can get away with it I would just run it wide open.

 

I agree 100%
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