my dads yamaha neos (polini 70cc, heavy clutch spring , original carb and filter) keeps cutting out every 15 mins and if we let it cool down for a bit it works again :/ we live in spain so its hot weather but what is causing this problem? it was fine last week and we changed the piston as the old one was fucked and now its doing this any ideas? thanks
what jet main jet you running ? you may have to up jet because if your overheating you may be running lean. Also try richening your air fuel screw so your running a little cooler at idle.
hello its the original jet i think...its had the same set up for a year since its been on and its been fine...and now its got a 1 ring piston on it if that helps and how can i richen it up? it doesnt idle anyway it cuts out if i close throttle
its not the cutting out at idle that bothers me its the problem where it cuts out when driving and i have to let it cool down :/
Well the more I look at this, are you sure you got the right sized replacement piston ? If you got an oversized one you could have clearance issues within your bore. 1 ringed pistons allow your engine to run higher revs due to the less friction that 2 rings have. Still higher revs still make considerable heat and if piston is too big, when it gets hotter it expands and will jam to the bore walls and into the ports, basically seizing! You could try honing your bore but I must stress don't do this UNLESS you are FULLY sure it will help! Also at higher revs its best to up jet... More fuel to cool down the bore. Final solution would be if your kit had a 2 ringed piston originally get a replacement one of them and forget the 1 ringed piston.
