I just had my motor rebuilt I had 11:1 hi comp pistons installed and Stage 1 hot cams ,I put it all back together and now I have a midrange stumble when holding the throttle,I did a couple of plug chops the front looked ok (142keihin main )the rear looked lean so I went from a 145 to a 150 (next size the dealer had) I thought it would be rich but it was a really lite tan. I have the radiator hose snorkle mod and a uni filter I don`t know if I should adjust the needles (dynojet adjusable set on notch 5 now)or maybe get bigger pilots. Please help.

 

I have some very basic mods and I am jetted at 142/145 and my plugs look perfect, you have to be lean. Do you have needle shims installed and are your air screws out 1/4 turn?

 

I have the dynojet needles on the 5th notch and air screws out 3 turns out from seated on both screws . I had the jetting set at 142 fr.145 r. with the stock internals but now with these pistons and cams the rear cyl. seems to be a little lean even with a 150 jet installed.