Motorcycle Repair: PAGSTA MINI, marine mechanic, mini chopper

Question
Hi Deron,
I was recently given a 2003 Pagsta Mini Chopper.  It had 67 miles on it and
hadn't been run in years.  The engine was originally a 49cc, but the previous
owner had upgraded to the 90cc? or the 100cc?The bike would not start due
to a compression reading of 30.  My friend who is a marine mechanic helped
me replace the top end gaskets and he cleaned out the valves.  We added a
new battery and a new spark plug.  The new compression came up to 130 but
still wouldn't run.  I took it to a mechanic that works on Chinese bikes and he
replaced the carburetor.  The bike now runs, but it stumbles in 1st and 2nd
gear when the throttle is turned past half way.  Then, it seems like 3rd gear
runs great and then in 4th Gear it seems to stumble every once in a while
when the throttle is turned 3/4 of the way or at full throttle.  I've added
Seafoam to the gas and squirted some into the carburetor and let it soak but
it still does the same thing.  I've also tried to check as many electrical
connections as I could find and sprayed them with electrical cleaner.  Any
ideas on what could cause the stumbling?   Timing maybe?  Do you know of
anyone who sells parts for these Pagsta's?  Thank you for your time.  I really
appreciate it!

Answer
Scott,
 From what you have described , I believe that  your jetting is off on the carb...sounds like your main jet is a little fat...try the next size smaller and see if that helps.

 I honestly have no idea where to get parts...all I could recommend is to google it and see

Good luck

D