Originally Posted by grizz1

Hi Johan,

You can use either carb, but the 3 needle was the production carb for the GXII-5RHO in it's last year of manufacture.
The 3 needle is a good carb.
Don't adjust the 3rd screw from the factory setting , and just treat it like a 2 needle carb for tuning.
The 3rd screw is not actually a needle, but an adjustable fuel tube. It is factory set for the best engine response, so mark it for reference, and just leave it.
You will get better power and response from the 3 needle carb on the 5RHO motor.

Hope that helps.