just a bit of input required, building engine up with 172 kit,cosa clutch,scootRS expansion, 26 mil carb, good set up??? and wat sort of jetting i should do
VESPADOCTOR, WELCOME BACK ANDY MATE, HOW’D YOU GET ON AT BEERACE’S AT THE WEEKEND.
The Keihin copy is a great carb. I’ve used on a derbi gpr 50 all kitted out and the only thing I had to change was the needle. The one the koso copy comes with is really to rich at 1/2-3/4. Just start with the keihin jjh needle and you should be in the ball park.
forget phbh 28 and try a real carb that wont cost a packet in fuel like a pwk28/30 or si26 set up right
I tried the 26 but was not impressed (maybe I just got it wrong?), go with phbh 28mm.
…and of course before changing the needle size I have tried the different clip position of the standard needle…
just on the carb question.
Keihin pwk is twice better then a dell’orto.
I have never tried the 28/30 but have 28 and a pattern 30 since keihin doesn’t make 30. Next up after 28 is 33.
I don’t know Koso pattern that SIP now have on their catalogue.
The only thing in my experience that I can tell you is that if you get one get also a spare needle of smaller size (to be richer in the mid). I found the right set up in two engine that I have using a smaller diam. needle then standard. The Keihin pwk 28 comes with neddle jjh. I got a jjg. As far as pattern goes i don’t know their standard setting.