Yamaha Zuma 50 2003 runs at 5 mpg

[yam]

Yamaha Zuma 2003 50 2-stroke I finally got it started give it to throttle and bugs goes about 5-10 mph at Max and dies only thing I know about the bike it has a 70cc upgrade power reads exhaust pipe header pipe don't know much about these bikes sorry don't know much about these things like I said know how to cheat out of clean the carburetors been cleaning the carburetor so many times it doesn't seem to be the carburetor bought a new battery new spark plug drain the fuel I don't know what else it could be please help

[aeroxbud]

What does the spark plug look like? Have you just installed the cylinder? Was there
any branding on the big bore kit? Some cheap kits really are rubbish.

[Zino]

take a picture of the carb and the main jet size

the air mixture screw should be between 1 1/2 - 2 turns out
try turning it one half full turn in either direction and see if it runs better


does the carb have 2 throttle cables coming out of it or just one ?
stock has 2
are you running air box with stock filter ?

try running it on the stand with the Airbox off and see if it revs up better
if it does you may be too rich

[mopedmofun]

If this was my bike, and I knew the carb was clean. I would play with my air intake to see if it ran better or worse. Hand over air inlet of factory air box with filter, just a finger, ect. This can be done really easy and give solid info.

[yam]

Don't know much about these bikes knowing I bought it it has a stock carburetor it was jetty I don't know the size just have the Jets I play with the air fuel mixture screw and it runs good for about a week and then it starts acting up again and going 5-10 mph the only means you transportation I have you get to help me out I really appreciate it

[classacted]

it may not be breathing. the first thing that I have seen happen is the exhaust port gets clogged with carbon. take the muffler off and look in the hole at the piston and carefully poke away at the sides of the hole until you see metal. don't damage the piston.