PW50 wont rev up new to the little bikes

[chilywily72]

Hi Guys I just bought a little Yamaha pw50 for my nephew at the swap meet for $100 guy said it didnt run but it felt like it had compression so i bought it. Took it home took the plug out and it had spark so i put some gas down teh cylinder and it popped off. Took the carb apart and it was full of gunk think it had been sitting for a long time so I bought a brand new mikuni off of ebay for it as well as a new choke cable cause it was frozen in the carb. I didnt want to trust the oil injection so i took the line going to the carb off and plugged it with a rubber cap.

Brand new carb, new air filter, new spark plug oil injection diconnected and fuel mixed at 40:1 the bike wont rev up it will start if i hold the throttle open but it wont rev past idle screwing with the air mixture screw does nothing at all anybody have any suggestions? I also took the silencer off to see if it might be plugged and it ran the same. Compression test on the first kick is 50lbs two more kicks gets it to 75 dont know if this is low. Any help is greatly appreciated!!!!!!!!!!

[mark0933]

Maybe it is a simple as the start/run/stop switch being faulty. The "start" setting will only let the bike run at a low rev (a little higher than idle, but not full open.

Just trying to help.

Mark

[bolinfamily]

i have one doing the same thing.. hope someone post the problem. if you find the fix please post it.

[Deleted]

I'm having the same problem

[jay42782]

take the petcok on the fuel line apart.just went through this with my sons 92 pw 50.started with cleaning the carb and jets.problem was the petcok.there is a filter in it

[Big Sam]

Compression should be higher, at least 100.


The previous guy is right. Fuel can gel up in the rubber hose coming from the fuel tank to the petthingy so check it. There is a second small black hose that goes from the petthingy to the carb so check it also.

Take the carb apart and clean out the 2 jets. They could be plugged up.

Check for air leaks at:1. Between carb and air box. 2. Carb and engine intake. Get the motor running (cold start) and spray starting fluid lightly around those connection areas. If the motor surges then you have a leak.

Also there is a ring compression gasket at the exhaust port that needs to be sealed. If leaking you can feel the air coming out. Use high temp silicone gasket maker on the ring gasket if leaking. (Take the exhaust off and reinstall it)