pw 50 won't start

[grandpa]

Hi everyone, new to the site. I just bought my grandson a pw 50 ( probably around a 1980) that won't run. I have spark when I take the plug out, but only when I ground it on a head stud. It will only spark on the start switch on the handlebars. The bike has compression and is getting fuel, but I am not sure the spark is hot enough. I have cleaned all connectors, replaced the plug, added fresh fuel. Is there a common electrical componet that goes bad on these older models? It has a faint blue arc when you ground the plug just right. Thanks for you help!!

 

[dirtpoor]

The plug has to grounded in order to produce a spark. I had a '99 PW50 that would start but when you put the switch in the "run" position, it would not rev pass idle. The off-run-start switch is prone to moisture problems. I had to use a heat gun to dry it and then it worked. I believe the switch affects the ignition timing to prevent it from reving in the start position. One of those safety features that's nothing but a pain in the :moon: in my opinion. The switch and/or the iginition and timing module maybe your problem if compression and proper air/fuel ratio are correct. Use a spark tester to see if you have a strong enough spark. Good Luck. :cool:

 

[Jasle]

check your exhaust port for carbon build up. it is very common for these to get so much carbon build up the exhaust port almost closes off. also they are very prone to cylinder damage around the exhaust port. you need to check your compression. if its real low like around 60 you'll be looking at a new topend.
What color is it? 82-89 were yellow and black. then they went to white-blue and then white-mauve then blue.

 

[grandpa]

Thanks guys for your help. To update you, I have cleaned the carb, but I cannot seem to get enough fuel into the cylinder. It has about 90 psi compression, I have cleaned all of the connectors, but when I put my hand on the back of the carb, I cannot feel it sucking any fuel. The exhaust blows out when it kick the starter. Any more ideas?

 

[grandpa]

P.S. The bike is yellow with a black stripe.

 

[Jasle]

pull the carb and reed cage. check to see if the reeds are stuck open. this can cause it to not start.

have you actually pulled the pipe to verify the exhaust port is not mostly closed. the exhause will still puff if their is a little hole in the carbon it will just not start...

 

[pw50123]

Pull the connector behind the front plate. It has 3 wires going to it. This will eliminate the start run switch and you can start in any postion except off. Also this gives you a higher rev limiter. Next step if this doesnt work is the carb. If the air screw is off too far it will not start.

Hope this helps :ohmy:

 

[CalisBestCR250]

i have a 90's pw50 and my problem was my choke i just removed it completely from the carb it takes a few more kicks but its running straight now even with a 245 pounder riding it

 

[Gazza2005au]

dont beat around the bush! pour some fuel down the spark plug hole try to start the bike let us know what happens you will get either of the following
#1: bike will pop or run for a few seconds (do not rev or try to)
#2: nothing at all happens
than we can go from there