KEIHIN carb settings

[StP]

Hi there, can anyone tell me what these numbers mean? I know they’re probably jet sizes but how do you interpret them? Thanks 

 

125 Min 50 - Max 115

250-270 Min 48 - Max 110

[peterb]

For a 125cc, pilot jet size 50, main jet size 115

For a 250/270cc, pilot jet size 48, main jet size 110

Seems a bit odd though, would have thought the larger motor to have the larger jet sizes. I don't know Beta specific Keihin set ups, but for a 250/300 GG, pilots around 40, main jet around 125-130 needle GJH. The standard JJH needle for GG tends to run lean for me. Bye, Peter B.

[StP]

Thanks for your answer. Beta say to adjust needle height to notch 5 and a max 1 turn out on air screw. This would usually make it run too rich? So that’s why the jetting is leaner? Thanks 

[pindie]

Smaller motors need bigger jets as the “pull” for fuel from the cylinder isn’t as much as it is on a bigger motor. Basically a 125 piston going down does not create as much suction as a 300 piston going down the cylinder. 

[nigel dabster]

On 3/6/2020 at 12:59 AM, peterb said:

For a 125cc, pilot jet size 50, main jet size 115

For a 250/270cc, pilot jet size 48, main jet size 110

Seems a bit odd though, would have thought the larger motor to have the larger jet sizes. I don't know Beta specific Keihin set ups, but for a 250/300 GG, pilots around 40, main jet around 125-130 needle GJH. The standard JJH needle for GG tends to run lean for me. Bye, Peter B.

Slide?

[nigel dabster]

On 3/6/2020 at 7:20 AM, StP said:

Thanks for your answer. Beta say to adjust needle height to notch 5 and a max 1 turn out on air screw. This would usually make it run too rich? So that’s why the jetting is leaner? Thanks 

tickover and needle positions need to be se to suit where you are fuel youre using etc. Competent person needs to do this.