Suzuki katana ay50 tuned but running so slow HELP?

I have a suzuki katana ay50 , and my dad has done the works to it , its got a top racing gear up kit , polini varitor, it has had the standard 50cc barrel ported, the reed stops bent back and the reed knife edged, the aluminiuim mannifold ported, the crank cases ported , its had new crank bearings , new wheel bearings , new swinging arm bushes , its had has various exhausts on and now has a techingas pipe on , it has been up jetted to .65 i think, its got the standard air filter on as it works better than with the K&N but there is a major problem :/. When i start my ped let it warm up it splutters for about the first 30 seconds and slowly creeps to 30 mph but if you go down a hill it will go 60-65 mph something kicks in . My accelartion on it is bad , but sometimes it will shoot right up to 25mph and then die down and slowly creep to 30mph , with my suzuki i have to duck down and wait for hit it to hit 40 and then max throttle and something kicks in and it flys straight up to 60 very quick , but the problem is my mid range and we dont really know how to sort this .and it also drinks petrol at the moment :/ if anyone knows what the problem could be then please help as ive had this problem for months,
Regards daniel


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why is there a gear up kit on a 50 barrel?

 

so do i need to add a 70cc kit ? to make the mid range better?

 

to be honest, i actually dont know. ive never known anyone to put a gear up kit on a 50 so i wouldnt know the symptoms. to be it sounds like u maybe running a bit too lean. have u checked your plug?

but yeah a 70 kit would be best option for a gear up kit. but ud need a bigger carb.

 

have you not tried looking at simple cheap things like rollers and clutch springs. this wouldnt be the main problem but its cheap to change and tweak and should prob help your acceleration if done right