Moped Army

Hi,

Ian here again... trying to get the PA50ii running properly!!

Thanks for y'alls help so far, we are getting close!!

OK... so we have a PA50ii... Boysen fiberglass reeds (the stock type)... new carburetor (one of the ones that are sold by Wyncycles on ebay out of Florida)... a Proma exhaust (WHAT A DIFFERENCE!!)... good air cleaner... no carbon blockage on the exhaust port... the variator is stock, working very well with new (stock) weights... basically, this thing has been pulled apart a dozen times, stripped, cleaned, polished, loved, etc!! (PS... I am going to post a video to youtube we just made of me separating the engine/drivetrain from the frame... 103 seconds baby!!)

OK... so... we fitted the exhaust, ran the crapp out of the bike, and it would soft seize every time... GREAT TOP END, but absolutely no power @ the bottom.
We drilled out the main jet with a 66 wire gauge drill bit (equivalent to an 84 jet), and it did nothing but flood the engine constantly!! It turns out, the carb from ebay has a very, very small main jet in it, about a 68 (we did not realize that the main jet that came with the carb was a 68, it was supposed to be a 78) so this is why it flooded when we drilled it out to an 84!!

OK... so today, we bought more drill bits and drilled out another main jet that we got from the guys on ebay (THANK YOU!! THEY SENT ANOTHER MAIN JET @ NO COST... WYNCYCLES ARE THE BEST!!) We used a 70 wire gauge drill bit (equivalent to a 71/72 main jet size)... now, this should, officially be way to small still, but the bottom end is now wonderful... lots more torque!! BUT... the top end has gone to crap!! SO, it will pull great from rest, but will begin to "break up" as soon as we get close to 20MPH. it sounds like fourstroking, but when we do a plug chop, the plug looks great... it does not look flooded, it is a nice tan color...

We are very nervous about drilling the jet any bigger, because this is the last one we can get and if we over drill it then we are kinda screwed... we could take it out a couple of more small steps, but, hmmm...????

SO... we are at our wits end... before, with the 68 jet, we had no bottom end and great top end (along with soft seizing), and now, with it drilled out to a 71/72 jet, we have great bottom end, but the top end has gone (and no soft seizing so far)

Any ideas guys???!!!

Thanks a ton in advance,

Ian :)

P.S. I have attached the document we are working with to figure out the drill bit size...

P.P.S. Does anybody know anything about the carbs on ebay and why the jets are so small??

P.P.P.S. Is there any other problem that would give the symptoms of fourstroking, but not be fourstroking??? We don't want to drill the jet out any more than we already have because if it is fourstroking, this would make it worse, no??? (could this be fuel starvation @ the top end???)