PW50 Help!

[nbarros]

Nothing...

So this time I looked for two things: the piston position and the carb.

Put the piston in its right position (thanks tnl!).

I notice a drop of gas from the air box! So I removed the air box and it was damp in gas in the bottom.

Ran out of time for the little troubled PW this weekend. I'm off to the mine tomorrow again.

Any ideas?

Temperatures have already dropped significantly here in YK. This weekend averaged 13oC HI. How do I start this bike in the cold?

[Pwmotorsports]

Just use the choke and kick as normal if gas is getting into the air box then the carb sure aint working right to me still think sticking float may be problem does it look ok ? would sure explain to much gas everywhere

[Smacaroni]

Yamaha's specs are for use with the oil injection pump in place. Running pre-mix makes it lean.

Forgive me for asking, but does it run, even briefly, with starting fluid?

If not, you have one of two culprits, lack of compression, or bad/incorrectly timed spark.

Even the worst carb problems should still run on starting fluid.

Finger over the spark plug hole is not a good way to test compression. Can you hold a 100lb weight with one finger? What about 50? 100 PSI is ok, 50 is lousy, but you can't tell the difference between the two because you probably can't hold a 50lb weight with one finger. Pick up a $20 compression tester at the auto parts store.

[tnl]

Why is it such a problem to just run the stock oil injection system?

[Pwmotorsports]

well for one many pw's out there have had them removed or unplugged allready when i was looking to buy one there were so many that ran pre mix but i waited and found one that didnt

[nbarros]

Just use the choke and kick as normal if gas is getting into the air box then the carb sure aint working right to me still think sticking float may be problem does it look ok ? would sure explain to much gas everywhere

It looks ok and it feels ok too. I guess when the floats sticks we have gas escaping the carb, right? That doesn't happen. The movement of the float seems ok and I believe the little valve is too.

Yamaha's specs are for use with the oil injection pump in place. Running pre-mix makes it lean.

Forgive me for asking, but does it run, even briefly, with starting fluid?

If not, you have one of two culprits, lack of compression, or bad/incorrectly timed spark.

Even the worst carb problems should still run on starting fluid.

Finger over the spark plug hole is not a good way to test compression. Can you hold a 100lb weight with one finger? What about 50? 100 PSI is ok, 50 is lousy, but you can't tell the difference between the two because you probably can't hold a 50lb weight with one finger. Pick up a $20 compression tester at the auto parts store.

It doesn’t do anything with starting fluid! Nothing at all. I had it sprayed in the air box, in the carb by-passing the air box, by passing the carb and even into the spark plug hole! Nothing… but the bike did start the other day (before I opened up the cylinder and posted the pics in here) and that was on gas. Only thing I did was install a brand new spark plug (note: the one bore this was just as new as the bike never ran with it… this one though was just out of the box).

What would a weak spark plug arc mean? I suspect it’s too weak now. I just compared it to the 4zinger and it is definitely weaker.

I agree on the compression ... and that's lame from my side! I’ll get one and check. It’s worth doing it.

Why is it such a problem to just run the stock oil injection system?

I found the pump to have a big leak, like lots of oil running down from under it. All lines were just fine and connected and the only place I didn’t see oil coming out of was the the other end into the carb, so I bled the tank and put on some pre-mix on the tank.

Look, right now I’m more interested in troubleshooting this thing and getting it to run. Once I do it I can restore this pump as I have 2 spare. Anyway, running pre-mix may not be ideal but the bike should start, right?

[Smacaroni]

Why is it such a problem to just run the stock oil injection system?

Cause most owners don't understand how they "just work". It's like black magic or something. If the owner doesn't understand it, it must be bad. It can't work. It must die.

It doesn’t do anything with starting fluid! Nothing at all. I had it sprayed in the air box, in the carb by-passing the air box, by passing the carb and even into the spark plug hole! Nothing… but the bike did start the other day (before I opened up the cylinder and posted the pics in here) and that was on gas. Only thing I did was install a brand new spark plug (note: the one bore this was just as new as the bike never ran with it… this one though was just out of the box).

What would a weak spark plug arc mean? I suspect it’s too weak now. I just compared it to the 4zinger and it is definitely weaker.

I agree on the compression ... and that's lame from my side! I’ll get one and check. It’s worth doing it.

Compression testers come in handy.

Ok, so my guess is you've got a serious electrical issue. With even minimal compression, it should run on ether.

The first thing I'd check with a dirt bike is gonna be all the stuff you can get to pretty easily.

Check the continuity of the stator and compare that to factory specs.

Test the plug coil.

I think you said you've bypassed the kill switch. Sometimes you gotta do it in the not-obvious way. Had an XR50 that would run with the key switch disconnected, shorting the terminals it would not run.

New plug... you did that, twice. You can try closing the gap for a stronger arc, perhaps 0.02-0.05" closer than it is now.

Check all the available electrical connections for gunk and continuity. I've seen ones that are connected that allow only 4V to pass through when it's fed 13V. Dielectric grease may help, so does sand paper - put a strip on a small screw driver and scrub.

Now assuming the above checks out, we have to look for harder things.

Open the stator cover and make sure the flywheel key is where it belongs and ok. It wouldn't surprise me if this is the problem because it runs sometimes and others not.

Again, if I mentioned something you've already done, I apologize, I've been quite busy lately and haven't been following this thread.

I found the pump to have a big leak, like lots of oil running down from under it. All lines were just fine and connected and the only place I didn’t see oil coming out of was the the other end into the carb, so I bled the tank and put on some pre-mix on the tank.

Look, right now I’m more interested in troubleshooting this thing and getting it to run. Once I do it I can restore this pump as I have 2 spare. Anyway, running pre-mix may not be ideal but the bike should start, right?

It should run. I don't have any experience with the 50s. However, the 80s will run on 10:1 oil to gas ratio, will run on pre-mix oil in the injector tank, will run on stale gas. Run on minimal compression (factory is 6:1) It should run.

[tnl]

So it ran somewhat with the origional plug in it before you tore it apart but you had to open the throttle to keep it running. At that point it is possible that the throttle cables along with the idle (screw on side of carb) are not in sync with one another right? IE: idle set way too low or the 2 throttle cable adjusters (one by handlebar and one on top left of carb) are not opening the throttle which is why you have to manually do it. Since you have a fresh gapped plug (not fouled) a piston head that is installed in the right direction, fresh gas and pipe/exhaust manifold carbon cleaned out and a properly jetted carb by Yamaha and a good start/run/off switch it must be timing or something internal right? BTW, what year is the bike? Aren't PW's pretty bullet proof? Isn't it unusual for them to have major timing issues assuming the PW isn't really old? Just trying to help!

[Pwmotorsports]

its common over here for stators to fail first manifests with poor starting then stopping when hot then total failure also sometimes you have to remember unless youve had the bike from new then who knows what people have done to them in the past.... Ive seen allsorts of crap on used bikes in the past so dont assume anything has been put together well when diagnoseing a problem like this

[Smacaroni]

The PWs are pretty well bullet proof, however, that doesn't mean there can't be one that fails either.

On top of that, he's got the extreme environment of the NWT to contend with, that will make a problem harder to find, because it's so much closer to the limits of the machine.

At least having Yamaha set the carb rules out possible problems there, I'm sure the local dealer is aware of any nuances with the PW carb and -50C to +40C operating. But then again, if your kid is riding in -50 (by either C or F) he's got bigger ones than I do. I quit riding at about 25F (-3C)

[nbarros]

The PWs are pretty well bullet proof, however, that doesn't mean there can't be one that fails either.

On top of that, he's got the extreme environment of the NWT to contend with, that will make a problem harder to find, because it's so much closer to the limits of the machine.

At least having Yamaha set the carb rules out possible problems there, I'm sure the local dealer is aware of any nuances with the PW carb and -50C to +40C operating. But then again, if your kid is riding in -50 (by either C or F) he's got bigger ones than I do. I quit riding at about 25F (-3C)

Wow! I said I have kids: two lovely girls, 6 and 4... not sled dogs!!! It does get cold in YK. Brutal cold like that and daddy will have his studs on his tires waiting for it to warm up to -20C at least, but the girls don't need to be exposed to that. They'll prefer hot chocolate inside, I guess.

Not even snowmobiles will function well under -40C... or at least the guys operating them! The bike is not set for that. The normal procedure of choking should do.

Yellowknife is quite interesting. It was 10C (POSITIVE) yesterday and it is 20C today. So I'm there working at the bike giving all I got to try to get the most out of this time around.

So it ran somewhat with the origional plug in it before you tore it apart but you had to open the throttle to keep it running. At that point it is possible that the throttle cables along with the idle (screw on side of carb) are not in sync with one another right? IE: idle set way too low or the 2 throttle cable adjusters (one by handlebar and one on top left of carb) are not opening the throttle which is why you have to manually do it. Since you have a fresh gapped plug (not fouled) a piston head that is installed in the right direction, fresh gas and pipe/exhaust manifold carbon cleaned out and a properly jetted carb by Yamaha and a good start/run/off switch it must be timing or something internal right? BTW, what year is the bike? Aren't PW's pretty bullet proof? Isn't it unusual for them to have major timing issues assuming the PW isn't really old? Just trying to help!

The bike is, I believe, 1982... and it was kept outside (here in Yellowknife)! But it worked! When I got it wouldn't give any arc in the spark plug and I quickly fixed that by simply removing all wiring, cleaning, drying it out and putting it back again. I also cleaned the carb, got a new spark plug and cleaned air box and filter element. The bike started right away, but then stalled. since then it's downhill. At least when I first got it to start it was just hard to keep the bike running. Until it would be really hard to even start briefly and now it will simply not start.

[nbarros]

. Compression reads at least 90 psi and I saw it getting right in between 100 and 110. Not perfect, but I guess it's alright, huh? Yamaha won't tell what it should be but I read all around it should be ~110 psi.

The procedure I used is from the (excellent) Clymer manual: kick it, with throttle wide open, until it reachs a maximum reading, but I also registered it as for one only kick and I got close to 80 psi most times. I got the readings above after kicking about 3 times.

. Electrical: I'm checking primary and secondary coil (of all 3 I have here). So far they seem alright, but I'm gotta make sure I'm using the multimeter correctly (as much as it sounds stupid for you guys... for an electrician I've always been an excellent mine engineer! )

. Carb: float is definetelly alright. I don't get any gas escaping from the gas line. The gas absorbed by the air filter is tricky though. I suspected the choke and the enrichment circuit, which Yamaha had to drill a small hole through as they found it was solid clogged... suspicious to me. So, I removed the air box, pulled the choked and kicked the bike. I could then see clearly a spray of gas coming out of the "choke hole" and out of the carb from behind where the air box would be fitted.

What can it be? Too much gas coming out of the carb...

I turned the pilot screw in and out again, made sure I got 1 3/8 turns. Would be a good idea to turn it out even more?

I also removed last week the exhaust and let it dry. It was amazing the amount of fluid came out of it. And it burns easily, so I'm assuming it's all the remaining messy stuff in the exhaust dissolved by gas that got into it. I'm still trying to start the bike without the exhaust in it and I also see a spray of gas printing in the workshop floor while I kick it. Some gas will accumulate at the exhaust port and drops will fall.

Also, the poor 4zinger that worked well before, now won't start either. All I did was swap the carbs. Got each other's carb back and nothing... I'm trying to start as if it was flooded now, but it's hard. I'll check it's carb once again.

Thanks guys!

[ih8opec]

what are you using to oil the air filter? liquid or spray? to much oil will keep it from running?

[nbarros]

what are you using to oil the air filter? liquid or spray? to much oil will keep it from running?

I use PJ1 cleaner and filter oil, but in doubt I removed from this one.

[nbarros]

Got the 4zinger to start again on starting fluid, but it won't last... Seems ok then suddenly looses idling speed as if some is turning the idle screw... then stalls. Oh well... she's not exactly the problem for now, so I'll levae it aside. But it's interesting to note the differences.

Got all excited ? and dumped starting fluid on the PW!!! Nothing... F...k!

[800tundra]

Was the 4 zinger completely flooded.Crankcase full of fuel?Seems odd that it won't run now. Only reason I could think if you put it back together right is other carb flooded it. Will the 4 zinger clean itself out after reved up?

[nbarros]

Was the 4 zinger completely flooded.Crankcase full of fuel?Seems odd that it won't run now. Only reason I could think if you put it back together right is other carb flooded it. Will the 4 zinger clean itself out after reved up?

Nope. I just tried that. Lifted the rear wheels, turned to RUN and started accelerating it slowly then hard. It went well for a while, choke was down already, then suddenly it stalled while it was reving up!

[txmxer]

Could you give a try to bump start it??? Although I dont know how youd do that on the pw maybe push it and go from off position to start???

[nbarros]

Could you give a try to bump start it??? Although I dont know how youd do that on the pw maybe push it and go from off position to start???

good point... is that how we do it?

[txmxer]

Seems like the only way you could just roll it get some speed going and then hold the throttle wide open and hit the switch down to run....or maybe start??? Try both.