Pw50 questions

Hi gang I recently obtained a 2003 pw50 from a friend and it is well kept and has the oil injection system hooked up. I have a couple questions and concerns that I hope you guys can help out with.

1. It takes forever to Start to where it needs starter fluid to start. What can be the issue?

2.the oil can is full, but when it starts and idles it doesn't smoke it will only lightly smoke if I throttle it while it is on the center stand. Is this normal or should it smoke more?

3. While I am riding it it seems that it will run fine then it will start to stumble and I have to let off to get it to throttle again. Any ideas?

Thanks guys alot

Probably a dirty carburetor. If they sit over the winter with gas in them, the little jets will start to gum up. Dissassemble it and clean all the little holes with carb cleaner and compressed air. You should see or feel the air coming out somewhere as you blow into them.

There is a little clamp ring on the injection line to the carb. Slide it down the hose, and then pull the hose off. Watch the choke spring, the small one under the carb cap. the brass end can slide off sideways, and the spring will go flying, I know from experience.

Just pay attention as you take it apart, the carbs are really pretty simple.

first start with a clean carb, clean air filter, new plug, carb set to factory settings, and good oil.

if it does not want to run, check compression, if low then change out top end.

also make sure your oil pump is dialed in and primed. priming it requires removing exhaust and bleeding the oil pump with the bleeder screw.

Hi gang thanks for all the info. So I cleaned the carb and it now starts perfect and smoke very lightly at idle and lightly while giving it gas. The only issue I am still having is there is still a stumble when i give it gas and if I let off it will go away and as soon as I give it gas it does it again. I adjusted the carb per the specs(1-1/2 fuel screw and 1700 idle) So what can be the issue now?!?!?

I need help guys thanks again.

It may stumble a little until it warms up, that is normal. Warm it up fully before adjusting.

Is it just off of idle, or full throttle? At low throttle, adjust the air screw. Full throttle, adjust the needle inside the carb slide by moving the little clip up or down. I am guessing you are lean, so move the clip down one slot on the needle (which holds the needle higher and allows more gas to pass). If it makes it worse, go the other way.

And do it where you can find the clip if you drop it....

I let the little bastard warm up(angry,frustrated). It seems that it is at full throttle, I will try to move the needle up or down right now and see if it helps. Thanks. I pulled the plug and it looks like there is a little more oil on it than usual, what could cause this? Should I just move to premix and pull the oil injection?

Thanks again. I will let you guys know what happens.

So I went out and the clip was on the second clip so I dropped it one down and it ran Like crap, so I put it on the very first grove and it ran better it still does the whole stumbling thing but I can play with the throttle to get by it. Is there anything else I can try to get rid of it completely? It happens if I pin the trottle it will start to climb in the rpms then it will cut off and I have to let off to get it going again. any thoughts? Thanks again guys sorry for all the trouble

Hey gang would I be having high RPM issues if the throttle screw is completely removed? And not just adjusted out?

I had the same trouble with my son's PW years ago. I would try pulling the baffle out of the muffler and cleaning it. Just make sure you put it back in, it will run like totall crap if you don't. Carbon tends to build up there because the bike doesn't rev enough to clear it out. Also, if you look on Ebay, you should be able to find a "power up kit" It comes with directions on how to mod the baffle, new reeds, jets, air filter, and a plug. It might have some more stuff? I don't remember? This helped TONS when it came to starting, and how it ran in general. You can also put in heavy clutch springs later if your kid feels the need for some more out of the hole punch? Hope this helps?:smirk:

When you say baffle do you mean the spark arrestor? Or the huge canister deal on the header pipe? Thanks

The spark arrestor is inside the baffle. Right by the rear wheel. When you pull it out, it looks like a torpedo.

Cool pulled it and cleaned with Gas and a torch, you can see right through it. Could something be really wrong if the original specs call for the needle to be on the 3rd clip and I put it on the first clip(very top) and it runs good? Does this mean I leaned it out completely?

there is a restrictor plate between the head pipe and the head, its just a shim that cuts off half of the airflow, which slows the bike down a bit. Pull that and see if it runs stronger and revs a lil harder. I pulled it on my sons pw and it woke it up considerably. It sounds like its loaded itself up, then choking itself when you get it revved up. Worth a shot anyhoo.

If the spark arrestor was badly plugged, pull the rest of the pipe (expansion chamber) and burn it out also.

Might want to check the compression too.

if its missing at full throttle, i would start testing your electrical components, (e.g. spark plug cap, plug wire, coil, stater)

i would not remove the oil injection, just make sure its dialed in correctly and bled.

if you think you have carb problems, ask others at the track what they are running on their carb, it will help you get dialed in for any elevation you may be at.

lastly, make sure you are running injector oil in there, its important to have the right oil.

Hey gang would I be having high RPM issues if the throttle screw is completely removed? And not just adjusted out?

Makes no difference if the throttle stop screw is removed.

Thanks guys for all your help, I cleaned out the baffle and before istarted it looked pretty good. I Cleaned out the sliencer and the header pipe and still runs the same, the washer was removed from the header by the PO so no change still stumbles and sputters. I did notice yesterday that it smoked alot during start up and after letting it warm up it would sputter through out the throttle range, then the smokE died down and it ran fine until full throttle it would sputter. The plug looks pretty oiled up could the pump be injecting too much oil? And causing the sputtering?

Thanks again.

Also what oil should I be running in the oil injector jug? I think I am going to swap it out. Could I just dump out the oil from disconnecting The line from the pump and filling the jug?

i think we may be confusing when you say "Sputtering" as either the motor missing or just not clearing out as the Pdub does.

yes, too much oil injected from the oil pump or the wrong oil will make it run badly.

adjust the oil pump as per the manual. the point on the plastic should line up with the screw.

run yamalube 2s in the bike.

pull the air box off and see if it helps run better on the stand or clears out.

I had the same trouble with my son's PW years ago. I would try pulling the baffle out of the muffler and cleaning it. Just make sure you put it back in, it will run like totall crap if you don't. Carbon tends to build up there because the bike doesn't rev enough to clear it out. Also, if you look on Ebay, you should be able to find a "power up kit" It comes with directions on how to mod the baffle, new reeds, jets, air filter, and a plug. It might have some more stuff? I don't remember? This helped TONS when it came to starting, and how it ran in general. You can also put in heavy clutch springs later if your kid feels the need for some more out of the hole punch? Hope this helps?:smirk:

My recently purchased 04 PW50 did not come with the baffle in the muffler. It was a raced bike so I figured they removed the baffle when they removed the oil injection. It seems to run good WOT but I'm still messing with the carb to get it to run right at idle. Only a week old and I've already cleaned the carb completely, but noticed the tube between the airbox and carb doesn't seal completely. More work to do on it, but this was the first I have read about the PW running bad without the baffle?? :smirk:

i think we may be confusing when you say "Sputtering" as either the motor missing or just not clearing out as the Pdub does.

yes, too much oil injected from the oil pump or the wrong oil will make it run badly.

adjust the oil pump as per the manual. the point on the plastic should line up with the screw.

run yamalube 2s in the bike.

pull the air box off and see if it helps run better on the stand or clears out.

The bike runs rough after it warms up and I drive it around tHe block, then it runs nice right until the RPMs climb It starts to miss and I have to let off and then it will run good again. it seems it only does it when the RPMs climb. I was thinking of just Bypassing the oil injection system and run a test tank of premix and see I this helps any, I think it maybe loading itself up with oil.

Does any one know the standard carb settings, like clip position,idle screw,and fuel screw? Thanks

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