I drilled the airmix screw cap on the OEM carb and closed off the air (clockwise) to just less than one turn open. Fixed it. I am at ~800 feet, and I still needed to adjust the airscrew after changing pilot from 40 to 45, main from 120 to 125. It was too lean (like you suspect).
The airmix screw on the youall smoothbore lets more air into the mix when you open it (counterclockwise). It is probably too far open. Those symptoms sound like what I had before making the adjustment.
Yours might be slightly different (variability in the jets and airmix seat), so the exact position of the airscrew could be a little different. But I get EXCELLENT response and power all the way across the rpm range. It isn't the carb, it is most likely the adjustment that needs changing. It is hard enough to get the OEM carb in there, but might be even harder to get the Nibbi in there
Quote:
Originally Posted by jc3
I can't get past 55 on the stock. There is a lot of popping and stumbling in the throttle. After about 30 minutes the carb over heats and just stalls out, probably too lean.
I have the extra cash lying around so I thought I would just compare the 2 carbs and document the difference for people. Hopefully tonight I can get back at it and get the nibbi tuned. I also found an interesting discovery on the OEM needle. I will post about this when I get home and get a picture.
I replaced the stock fuel filters as well.
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