PW50 Issue

Related:
Create New Tag

12/30/2020 5:11 PM

Hi, I have read through a lot of threads on here about PW50 issues and they have been very helpful.

Bought the bike back in Sept. and it was in pretty good shape, it ran OK but I have never ridden a PW50 so I don't have anything to compare to. Seemed slow but good enough for my 6 year old as her first bike. I put a throttle stop on it at 1/4 throttle.

2 days ago the bike was really low on power and my daughter couldn't get it to move under her. Then it started to cut off and wouldn't idle without the choke on.

Here is what I have done so far:

- checked compression when cold: 130 psi after 10 kicks, seems good according to the threads I have read
- checked plug, see pic, tan in color, throttle stop is set to about 1/4 throttle
- opened up carb and check for plugged jets, check jetting, pilot: 40, main: 70, needle: 3x24 no ability to change clip, everything looked very clean
- checked header pipe for block plate, was not there
- burned exhaust pipe with MAP torch, stuck torch in header opening and let it get red hot, did the same on other end
- unplugged the connector behind number plate, now it starts in "start" or "run"
- new air filter
- cleaned filter at petcock
- fresh gas

I am stumped and my daughter is disappointed she can't ride her bike. Any help is greatly appreciated.

|

12/30/2020 8:17 PM

What kind of oil are you putting in the oil jug? Make sure you use stuff only intended for oil injected bikes. Like the yamalube or Maxima Super M Injector oil. Also, I had similar issues with my sons PW and just bought a new carb for like $30 and it’s worked great since. I tried cleaning the old carb and it seemed clean but it wouldn’t run right.

|

12/30/2020 8:25 PM

i use sea foam in every tank of gas with my sons PW which had carb problems from the start.

|

Midlife-moto.com

12/30/2020 9:06 PM

agn5009 wrote:

What kind of oil are you putting in the oil jug? Make sure you use stuff only intended for oil injected bikes. Like the ...more

I second the 30 eBay carb. They are basically disposable. Could never get my sons to run right with the oem carb after a while. Tried an eBay special for the heck of it and she ran perfect again. 6 months later and a ton of hours in really dusty conditions, started runny like crap again. New top end and Cleaned the carb to no avail. Threw another new eBay carb on her and runs perfect again. The carb orifices are so small they get plugged easily and the stock filter/airbox isn’t exactly the best setup for keeping things clean. That’s where I would start

|

12/31/2020 6:22 AM

My kids' PW had the same problems and I did all the stuff you did. I finally just bought a $18 carb from Rocky Mountatin and it has ran fine since.

|

2008 Honda CRF450R

12/31/2020 6:46 AM

Funny enough, we had this same exact issue with ours last week.

I was thinking it was some adjustment I got wrong when I put on the throttle cable last week. So that begs the question, why does the throttle cable split and what the heck is it hooked to in the back of the motor?

|

12/31/2020 8:25 AM

LungButter wrote:

Funny enough, we had this same exact issue with ours last week.

I was thinking it was some adjustment I got wrong when I put ...more

One goes to the carb slide and the other goes to the oil injection pump..

|

'22 CRF250R...??
'21 KX250
'20 KTM SX-E5
'21 Husky EE-5
(2) STACYC 16eDrives

12/31/2020 8:53 AM
Edited Date/Time: 12/31/2020 8:54 AM

LungButter wrote:

Funny enough, we had this same exact issue with ours last week.

I was thinking it was some adjustment I got wrong when I put ...more

One into the carb and one into the oil injector.

Edit: oops soopah already answered.

|

12/31/2020 11:04 AM

Rocky Mountain or EBay carb is the answer.

|

12/31/2020 11:09 AM

jmvar44 wrote:

Hi, I have read through a lot of threads on here about PW50 issues and they have been very helpful.

Bought the bike back in ...more

Even though everything in the carb looked clean, did you use any emery cloth or anything to physically clean it? If my son's sits for a few weeks then I have to go through that. Takes less than 10 min.

|

12/31/2020 11:15 AM

Try putting some seafoam in it , remove throttle limiter and run it for a few minutes or longer up on stand.

|

12/31/2020 12:36 PM

Also check the electrical connections behind the front plate. Some water got in ours from washing it. Once I cleaned them up, I had no more issues. The bike was sputtering and shutting off.

|

12/31/2020 12:47 PM

jmvar44 wrote:

Hi, I have read through a lot of threads on here about PW50 issues and they have been very helpful.

Bought the bike back in ...more

JWW85 wrote:

Even though everything in the carb looked clean, did you use any emery cloth or anything to physically clean it? If my son's ...more

I took it apart and blew air, carb cleaner through all orafices.

What should I be cleaning with emory cloth?

I will try cleaning electrical connections, cleaning carb with emory clith and seafoam.

If that doesnt work its off to ebay for a carb I go.

|

12/31/2020 1:04 PM

jmvar44 wrote:

Hi, I have read through a lot of threads on here about PW50 issues and they have been very helpful.

Bought the bike back in ...more

JWW85 wrote:

Even though everything in the carb looked clean, did you use any emery cloth or anything to physically clean it? If my son's ...more

jmvar44 wrote:

I took it apart and blew air, carb cleaner through all orafices.

What should I be cleaning with emory cloth?

I will try ...more

I hit anywhere i can reach inside the assembly, the throttle valve/slide and the needle (lightly). Then, carb cleaner and blow it out with air.

|

12/31/2020 1:09 PM

Varner usually picks up 3rd or 4th ring. Hes the guru all those

|

12/31/2020 1:32 PM

PW50's can clog the exhaust port and the muffler with carbon. Remove the exhaust and see if the exhaust port is plugged. Same for the spark arrestor. Also, run it with the exhaust removed, if it's plugged it will have power with it removed.

If you unplug the connector but the wires are shorted together on the harness side the bike will run as you have it in start mode.

If the choke makes a difference that might be a clue. Are you lean? Is there water in the fuel? Water in the fuel will make it not rev and be very inconsistent revving and then nothing. Broken reed?

You need to narrow down if it's electrical, fuel, or mechanical. Add air by running with the airbox off, add fuel by running with the choke, any changes? Try pulling the plug cap off and just set it on the plug, this will increase your spark, any changes? Lightly blow an air gun in the intake while running, any changes? Remove the plug cap and shove the wire on the plug, any changes? Keep testing and you'll figure it out. We have a tool that goes between the plug and the cap, for testing spark, when it's the governor is stuck in the CDI you can see the spark dissapearing on the tool and it makes for quick diagnostic of a bad CDI.

|

12/31/2020 2:53 PM

Wow, thank you all for the suggestions. I will systematically go through diagnosis and report back.


Thanks again and happy new year.

|

12/31/2020 3:23 PM

I know you said you cleaned the carb and a bunch of folks mentioned they did the same...then ended up buying a cheap carb and boom, it works. Anytime anything of mine that would only run with the choke on...the pilot has always been clogged. But then, I've never taken a pw50 carb apart to know that the heck would be wearing out in those things.

|

12/31/2020 4:50 PM

x2 on the carb. Buy one and swap out and see if it runs better

|

12/31/2020 5:03 PM
Edited Date/Time: 12/31/2020 5:05 PM

Every mini ends up with carb issue due to dirty fuel
Must run small inline filter before carb
RC motors fuel filter

|

1/1/2021 8:34 AM

soopah noviss wrote:

One goes to the carb slide and the other goes to the oil injection pump..

So that’s what that is 🤣

|

1/2/2021 1:11 AM

Had the same thing happen to my sons bike . Problem was dirty blocked jets . Put new jets in and ran like normal

|

1/2/2021 1:47 AM

Clean the inline screen filter on the inlet side of fuel tap. Remove with suitably sized self taper, blow backwards and clean with contact or brake clean and blow again. Reinstall. Failing that, remove exhaust and clear out the carbon choked in header. Or both.

|

1/2/2021 5:52 AM

x2 exhaust gets plugged up. Easy test, take exhaust off see if it solves the issue.

|

1/2/2021 11:54 AM
Edited Date/Time: 1/2/2021 11:56 AM

Hey so since we’re on the subject of PW 50’s and there’s lots of guys with experience in here I have a question for you. I found one for a good deal so I scooped it up for our grand daughter. I haven’t had time to fiddle with it yet but here’s what it does. When you rev it out and then chop the throttle the rpms hang for awhile then SLOWLY drops back down to an idle. It’s like it “runs on” for lack of a better description. Any ideas ? Thanks

|

1/2/2021 1:03 PM

Idle hang up is usually attributed to lean idle mixture either through carbaration or intake leak. First make sure you have some throttle freeplay and cable moves freely. Cables are cheap and make a huge difference to the feel and operation of controls. Especially drum brakes. The intake boot on air filter side on these notoriously go hard also and dont seal at either end. Give it sqeeze and if it doesnt order new along with an airfilter or 2. Cheap at $5 genuine. The air boot also has a cut out on the carb side that must line up with the air bleed hole at the rear base entry of carb. Also a couple of locating taps that line up with notch on airbox and get you in the ball park. You can rotate the boot like a 16th to 32th of a turn either way from this pisition with the engine running at idle and full revs on the stand to find the sweet spot. Unless the engine is on the way out you wont blow it up revving the piss out of it at full throttle for a minute or even 2 clean out the exhaust now and again if the kid is not a demon and it will burn the oil and carbon out and when done right will smoke smolder for a bit after shutting down.
All this should be done after the carb has been thoroughly disassembled and cleaned in an ultrasonic tank if you have one. Another thing to do is junk those large block standard tires and put on the Pirreli or Maxxis tires with much more aggressive pattern to save them sliding out so easily. And a top end rebuild if not much compression or resistance on kick lever with your hand. If al that is good, years of trouble free riding.
Good luck and dont push them too hard or be in a hurry to get them on a KTM 50 if they're low on confidence.

|

1/2/2021 1:42 PM
Edited Date/Time: 1/2/2021 1:43 PM

Thanks Lurk ing great info. She turns 1 this month so I have lots of time to go through it but I noticed the run on thing so I thought I’d ask. We had one for our kids and I don’t remember it doing that. I’m in full agreement on not pushing kids into this stuff. She’ll have the same rule our kids did, she won’t even see it until she can ride and skid a bicycle, and then it’s all about fun. No pressure. You want to ride ? Ride. You want to throw rocks ? Throw rocks 😂. They have their whole lives to get serious about it if they get the bug.. She’ll grow up around the sport and riding and camping in the desert so the seed will be planted, if it grows fucking awesome if not that’s fine too. Our theory on moving up to bigger bikes is nothing is funner than a bike you can throw around and ride the fucking wheels off, we keep them on a bike until they’re a little too big. Again the focus being fun. Thanks for help ! 👍

|

1/4/2021 8:17 AM

Update on my issue, I was narrowing down whether my issue was fuel, air, or spark and I kept coming back to the fact that the bike would idle with the choke on but would die a couple seconds after the choke was closed. It would also idle when I gave it throttle on the stand.

I assumed this was a fuel issue with the pilot jet so I removed the carb again....then again....cleaning out the pilot jet and passage but couldn't see any obstructions. I ran the bike with not pipe or air filter and it still wouldn't idle. Took the carb off again and realized I never blew out the air screw passage the first 2 times I cleaned the carb. Removed the screw and blasted it with carb cleaner. Let the bowl drain out and now the bike will idle.

I removed the throttle stop and now the bike runs much better.

I will still preemptively go through the electrical connections and pack with die electric grease but for now all is well.

Thanks for all of your help and suggestions, I am sure this will help me and anyone else searching for answers in the future.

|

1/4/2021 9:06 AM

I went ahead and threw the $17 carb on a Rocky Mountain order yesterday since so many guys said that was a fix.

Mine is a 2000 model so I'd say after 20 years and 5 kids the carb has probably run its course.

|