Need help with off and on engine sputtering

[mike69]

Ive got a 2010 apex 90 24mm flat slide carb. It will run all right off and on. On stand it will sometimes run out clean and then all of a sudden with it at half throttle just spudder. Jetting was 128m 48 pilot clip in 3rd. Now it is 125m 42 pilot clip2nd from top. I think the jetting is better, but im just lost at why it would act like this. If you start it cold warm it up briefly and take of it will run real good for 30 sec or a min then do all different scenarios. Any help would be much appreciated. Thanks

[fomospede]

try a different carb that you have seen work correctly

[ontargetracing]

I had an issue like that one time... it was the fuel filter. It had come apart on the inside and sometimes it worked and sometimes it blocked the gas flow. Drove me crazy for three days trying to figure it out.

[mike69]

Thanks guys. I do believe its a fuel problem. Tore down the carb and all looks good. Ill check the filter.

[selbygirl]

i would check all your electric fitting, make shore there tight and clean. I would hard wire every thing get rid of the factory connections on all our bikes,, then we started using pvl , check spark plug also and plug wire take apart cut a 1/4 inch off both ends and put back together , and check all your grounds, on all our bikes I would get rid of the cock pit run the the hose strait from tank to carb . you can get a cockpit that you use on lawn tractors and gas filters .most auto parts stores sell them , and some times a weak shoe spring will make it feel like a carb problem .. if its spitting and sputtering .and if the plug is blackish and wet most likely electrical ' plug should be a good brown color

[mike69]

Thanks for all your help. I got it running last night. I had the carb completely apart. Didnt see anything. As i was putting it back on i notice a little slit in the fuel line going to carb. Didnt notice any leaking. When i checked it it was all the way through. I put a new one on and ran like a dream. I was getting ready to run a new group wire and all of a sudden its fine. Not sure if that was it but.. Hay its running. Raced this morning and was great until final lap and it quit pulling when it was back at teuck cooled off its pulling again. The spring was just put in. Ugh. I dont know what to do with this thing. We had a drr 70 and rode the wheels of for 3 1/2 yrs and only put one spring in it just because someone said i needed to. Ugh!!