MOPED ARMY

i would check to make sure that the exhaust is not clogged. take the mufler off and try to run it that way. Dont do it for too long maybe 3 minutes. if you do it too long you could seize the engine. so take the muffler off try to run the moped like that, if it helps that mean you probably have a clogged muffler otherwise it might be your fuel mixture. let me know if its the exhaust?

Make sure the oil the the transmission is motorcycle crankcase oil ie meant to be used with wet clutches. If it is regular motor oil with additives, the clutch won't operate properly. Just a thought.

ok it came with automatic transmission fluid in it, so not having a service manual i put tranny fluid back in the gearbox. But would that cause the problem? I mean it is alot thinner than gear oil. Ill take the exhaust off, check that and adjust the carb. Thanks, ill let you guys know

Why not get a small engine shop to give it a compression check. As for the transmission, you should put in 20w40 oil. I use Yamalube, but I think I've read that WalMart sells it too. It should be the kind without the friction fighting additives ie. for wet clutches. Have you looked at the large gear that is on the shaft that the rear wheel is on? The last gear in the drive-train. I've seen a couple that are completely stripped out or on their way to that condition. Wouldn't hurt to give a second look to see if the gear teeth are meshing completely and properly. We'll get to the bottom of this..eventually!

yea, my fa50's gears in thegearbox have 0 wear to...and mine is from 86' ....i think the gearbox gears are the highest quality thing in the mopeds.

Ok its making 126psi. Thats good. I also filled it up with the right oil. I decarbonized the whole engine and it now moves and gets up to about 15 mph but if I open the throttle it bogs and stumbles. Does my fa50 have a CDI ignition, cuz that would rule out timing probs right? I'm almost certain its the carb, either too much or not enough fuel. Anyone know anything about the auto fuel switch, is it vacuum operated? I've also cleaned the carb out thoroughly, but maybe theres just one little spec stuck up in there.

I had to clean mine three times before it ran right. I read awhile back that FA50s are particularly sensitive to dirty carbs. The fuel pump in the petcock assembly is vacuum operated. You might put an in-line fuel filter on at some time after you get it cleaned up. Did you check for a vacuum leak at the carb? Use search function if you aren't sure how to do it.