StP Posted March 4, 2020 Report Share Posted March 4, 2020 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 Quote Link to comment Share on other sites More sharing options...
peterb Posted March 6, 2020 Report Share Posted March 6, 2020 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. Quote Link to comment Share on other sites More sharing options...
StP Posted March 6, 2020 Author Report Share Posted March 6, 2020 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 Quote Link to comment Share on other sites More sharing options...
pindie Posted March 8, 2020 Report Share Posted March 8, 2020 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. Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted March 9, 2020 Report Share Posted March 9, 2020 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? Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted March 9, 2020 Report Share Posted March 9, 2020 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. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.