Last year I bought a stock PX150 05í, still in the crate after 14 years. Had all the stock jetting and catalyzed exhaust. Replaced those with the SIP Road 2 exhaust and usual suggest jetting (102 main, etc). The first 1/8th of throttle has a Ďcoughí/rough running, missing sort of thing going on, but the mid and upper throttle are beautiful and torquey. I canít figure out whatís up with the lower end of the throttle. I donít think it is a jetting issue, iíve swapped the stock 50/160 and 55/160 back and forth, tried dialing the mixture in. Starts fine, idles fine, just struggles as I start off or lower the throttle to 1/8th or so.
Any ideas? Is this just a byproduct of having the added backpressure of the road pipe? Or maybe timing, or air leak? Any help appreciated.