PW-50

[bbuckler]

Hi I'm new here. I bought my nephew a 1986 Yamaha PW50 and it runs good for a little while and then is dies and smokes from around the exhaust manifold. Is it just the exhaust manifold gasket or does it need rings ?


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[ricky_191]

It could be a few things. It could be the gasket. Just pull the exhaust off and check that it has one there. If it has a little washer in the end of the pipe, pull that out too because it will go a lot better and faster

Also can you post up a photo of it ? I have one that's roughly the same age.

 

[my67xr]

hi, welcome to Miniriders,

make sure you drop by and say g'day in the Introductions thread too, and post up a pic of the bike while you are at it.
Introduce Yourself thread


with it smoking at the exhaust manifold gasket, i would say it may be running a bit rich ?
does it still have the oil tank mounted behind the front numberplate ?
or are you running Premixed fuel through it ?

the original exhaust manifold gasket is fitted with a restrictor ring inside it.
this is to help young ones to learn to ride, before removing it once they gain confidence, and giving the bike a bit more power.
if you drop the pipe off the head, the gasket should be sitting there, or stuck to the head.
pop if out and check that the restrictor ring has been removed.
if you look into the pipe and there is a fair bit of carbon/oil there i would recommend that you burn it all out.
it will restrict the bikes' performance and can also cause it not to run too well.
if the exhaust gasket is us, they are easy to find, this will do the trick, and you'll have a spare too-
http://www.ebay.com.au/itm/Pit-bike..._Parts_Accessories&hash=item4ac65cbe2d&_uhb=1


i have a PW50 i fixed up for my son too,
the link to the build thread is below in my signature.

cheers craig

 

[bbuckler]

It has a oil tank.


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[bbuckler]

I will get more later when I can pull it out of the shed


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[bbuckler]

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[my67xr]

that looks like a good starting point.
it's pretty much all there

are you any good pulling carbys apart ?
i think it would be a good idea to give it a thorough clean out

 

[bbuckler]

Yeah I fix lawn mowers. I rode it all day today and it didn't cut out at all.

 

[bbuckler]

will this fairing kit work on it http://www.ebay.com/itm/BLUE-YAMAHA...d=100033&prg=1011&rk=3&rkt=4&sd=331056134204&

 

[my67xr]

yeah, they are chinese reproduction plastics, they are pretty cheap too,
some of the holes may need some fine tuning to line up the bolts etc


but,
having genuine Yamaha plastics on your bike will make it worth more if you ever want to sell it.
there was a late model set of original Yamaha blue plastics for sale a while ago, locally to me.
the guy wanted $60 for them, i wish i had the spare cash to buy them for spares.

 

[bbuckler]

For a 7 year old justing learning it sounds perfect. I order new tubes for the tires,air filter,training wheel and a carb today for it.

 

[my67xr]

yeah those plastics will be fine.

the Uni Filters are pretty cheap for them, about the same cost as genuine Yamaha foam filters.


what trainers wheels are you thinking about ?
there are a lot of people selling home made ones here, but the don't allow for the rear suspension to move
they are basically a long axle that bolts to the bottom tube of the frame, and a couple of sack truck/trolley wheels on the ends.
the genuine Yamaha trainer wheels are not too bad, they call them 'Stutter Bump Trainers'.
and have a spring built in to each side, and just bolt up to each side of the rear hub of the bike.
they are more of just a helper for stability, not so rigid as normal trainer wheels.
the same trainers also fit the later Yamaha TTR50's as well.
i would try looking out for a set of used ones, genuine new, are approx $120 a set here.

are you in the US ?

if you were in Australia, i'd consider buying the white/red plastics off you.

 

[bbuckler]

Yeah I'm in the us.

This is the training wheels http://www.ebay.com/itm/YAMAHA-PW50...Parts_Accessories&hash=item3f254a3d95&vxp=mtr

Air Filter http://www.ebay.com/itm/281185467052?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

[my67xr]

those trainer wheels mount to the bottom bar, and are not adjustable either.
on some you can raise them up up to 2", once the kids get their confidence up.

that Moose filter looks good, and is half the price of the Unifilter too

 

[bbuckler]

The new carb and air filter is installed I will try to install the new inner tubes tomorrow.

 

[my67xr]

did you just replace the carby ?
where about did you get it and how much ?

 

[bbuckler]

did you just replace the carby ?
where about did you get it and how much ?

Yeah I a got a new one and it runs and sounds a whole lot better. It was $19.00 on Ebay http://www.ebay.com/itm/370432092860?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

[bbuckler]

I thought it was fixed until today when I gave it to my nephew it ran for 5 min and then lose power now it will run and throttle until a rider gets on it. It also getting really hot is this a plugged exhaust problem?

 

[Blender]

I thought it was fixed until today when I gave it to my nephew it ran for 5 min and then lose power now it will run and throttle until a rider gets on it. It also getting really hot is this a plugged exhaust problem?

it could also be running lean, with your new carb did you check what jets were in it?
But its also a good thing to your expansion chamber, burn it out with a gas torch. Craig (my67xr) is the expert though!

 

[my67xr]

yeah, as Blender asked,
what jets are in the new carby, compared to the originals in the Mikuni ?
and did you oil the new Air Filter too, before fitting it ?