pw50, need help!!

[kyle]

am a pretty good mechanic, have experience in a few different shops, but this one stumps me. I bought my little brother his first dirtbike, a pw50. Hes a little big for it at 80lbs, but he doesnt know how to ride yet. When we gave it to him, it ran good for a little while. then we started having fuel issues. I removed the stock fuel filter in the petthingy because it was cloged, and way to restrictive. It ran good for a little longer, and then then started to stall once it was warmed up. i decided it was a clogged carb, due to the lack of a fuel filter, so i thoroughly cleaned the bowl, float, needle and seat, jets, gas tank, and everything fuel related. Yet again it ran good for a little bit, but then started to stall once warmed up. 80lbs is a little much for the little big, but it should still pull it without stalling. On the throttle cable it has a splitter, and the carb slide returns while the other cable does not. I am not sure what this cable is, but i assume it is some type of a simple trottle positioning mechanism that compliments the automatic tranny. I was wondering if anybody else had this same problem, and if they figured it out. If it has something to do with that 2nd cable, could it possibly be stuck startin out in second gear? and maybe while its cold the clutch slips enough to let the bike start in 2nd but when it warms up it disengages and the motor stalls? one other thing that would lead me to this conclusion is that is idles fine, choicke or not, warm or cold, all day long. feedback would be greatly appreciated, thanks kyle.

[PWDAD]

weight should not be an issue I am 200 pounds and I ride my sons PW all over the place with no problems...and the little thing will wind right out...mabye your gettign some blow by or the plug could be the wrong one for the bike and getting to hot and stalling it out...make sure your plug has the "bp" on it that is the right series fo rhte bike...there are also many upgrades available for the PW's that will make it fly...hope this helps

[Alan]

I have a few of these little bikes and have found most dont run well. Alot of people fight with these without good results. I would start by checking the integrity of the engine by doing a comp test (dont skip this test because if the comp is low it will never run good) It may take 10 kicks or so but it should have at least 100 psi. Spec is 120 from yamaha. The next thing to do is get rid of the oil injection. That is the other cable in the splitter you were talking about. It hangs up due to the pump is shot and stuck wide open dumping in too much oil. I run all mine with the pump out premixed at 50:1 with amsoil dominator oil. If you run them too rich (oil) they foul plugs easy. Your trans it only one speed there is no 2nd gear. Run a fuel filter wheather its the stock one or an inline unit, but put one on. Set the needle clip on the carb at the second groove from the top. Put the idle/air screw at a 1/4 turn out. Stock is 1.5 but running premix leans the carb out so you need too compensate for that. Leave the main jet alone. Make sure the ex. restrictor is out. I would take the pipe off anyway and check it for carbon buildup. You may need too pull the jug off and clean the cabon out of the intake and ex port. I have seen them plug up alamost complete. And one last thing if you want to get more low end power go on ebay and get a QT50 moped rear final drive unit. They are geared alot lower and really make the pw rip. The first one I had would not hardly move. Now my boy is out rippin up the yard scarin his mom. Take a little time and check these things out and yours will run good.