Anyone ever jetted a ported bike?

[2fittyr]

I just rebuilt my motor, bored over twice since new sleve, ported and polished the motor, it has an old fmf also. right now its got a 165 main and a 45 piolit and the clip on the 2nd slot from the bottom. I have already tried a 160, 168 and 170 main and they all ran horible. The bike runs alright at quarter to half throttle but once it gets above that it just starts sputering and i cant figure it out. No shop within 30 miles of here will work on it because its been ported so now im screwed. any help would be greatly appreicated. thanks

[Hoppedrap]

Did they modify the head (raise the compression), if so make sure you regap your plug @.018. Higher compressions tend to make the spark go out

[darren250r]

What size carb do you have? Is your bike still a 250? What altitude are you at? It sounds like you are running too rich. I would start by raising the clip on the needle to the middle or maybe even one notch above the middle to try and lean out the mid to top end. If it still craps out on the top end I would go down a jet size. After every change you should take a look at your plug to see what color it is. It should be a light tan, white too lean and black too rich. You might also try to put a brand new plug in because I have had several brand new plugs be defective from the manufacturer and if thats the case you will never get it jetted right until you have a good plug.

Darren

If it matters, I have a 38mm carb on my 330 at sea level and I have a 170 with the needle clip one notch up from the middle and it is still a bit on the rich side.