Yamaha PW50

[ricky_191]

Hi all, This is my PW50 that I fixed up and got going. I know it's only a peewee and it's only for a bit of fun.

I got it off my cousins because they were making room in there shed and were throwing it out so I took it I put it in the back of my tiny hatch back and brought it 300kms home. It only took two days to get it going again because it hadn't run in two years..

First I got rid of all the old fuel out of the tank and carbie and cleaned it all out. I got a new air filter and replaced the air box that sat under the seat. I replaced the spark plug,changed the oil, new fuel and went to start it .. but it didn't go.

I checked over the wiring and it all looked fine and it turned out to be the wrong fuel mix. PW50's have a oil mix system that normally breaks and causes the engine to run with out oil so these are normally cut off and fuel gets mixed in the tank. The problem with this is no one knows what oil mix to run because there is no specs. Through some experimenting the oil to fuel is around 40 to 1.

After getting it going with a new batch of fuel I took off the stock bars and replaced them with a set of protapers but now they are on the pit bike.. This was a problem because the stock bars are a lot smaller and the throttle wouldn't fit over the new bars. So I spliced in a pit bike throttle into the old mixing part , joining the stock cable with a new one. More on this later.

Then I had to make some mounts for the new bars and I used some 2cm box steel and bolted them on with the stock bolts and then bolted some pit bike mounts onto the steel.

With the bars on I got all the rust off the frame, treated it and painted it all black. I got a set of spare wheels with it and sprayed them black and fitted the best set of tyres that come with it with some new tubes.

I think this bike has been modded before because the restricter was taken out of the exhaust pipe and the clutch is pretty good. It caries my 85kg frame well


This I one of the only pictures I have of it after I stacked it into a bank flat out.. I fixed the brakes after that week end

I'm fixing it up again and putting the handle bars that come off the pitbike onto it and also a new throttle and cable. Thanks for reading.

 

[Blender]

nice one dude, those peewee's are great bikes, alot of fun. what year model is it? Craig (my67xr) built one and did a hell of a job, so that thread would be pretty useful to you i imagine

 

[ricky_191]

Thanks.. I don't really know what year it is. Some one said the date is stamped in the wheel but both are different dates.. I think it's roughly an 85 and I don't know much about it's past. It is so much fun, with the big bars you can fit your legs under them and ride it like a normal bike. I have had a few of my brothers mates get on it after a few drinks

It is so strong as well and it's not as slow as I thought it would be. I'm not sure what's been done to it but it's pretty fun. I come off it going flat out and crashed into an ant hill and the bike was fine and it's small so it fits in my car

 

[Blender]

yeah, the yammies have great power, the fastest bikes around IMO. your right, they are great fun, just so easy to throw around! what are you planning on doing with it as far as mods go?

 

[ricky_191]

I removed all the crap out of the exhaust and it went faster, I removed the stock air box and put a pit bike air filter on it and that helped it breath more.. You can mill the head a little to up the compression and a new set of power reeds. You can get a performance exhaust and a fair few aftermarket parts for them. Another great mod is a drive shaft from a 50cc jog scooter that makes them go a bit faster.

I might keep it a bit stock and just have fun with it and focus more money and time into the pit bike but it's still a great bike to have around. I haven't ridden it for a while because I broke the throttle off it and then got a new one with a long cable but I had to chop the end off and shorten the sleeve.I didn't know how to put a new bead on the end but I end up putting a ball of solder on the end and it worked really good. I kinda forgot about it for a while and then took some parts off it for the pit bike but i'm going to get it going again

 

[my67xr]

good score there !
that is an early one, same as ours, it's maybe 81 - 83 model ?
there is a number on the r/h front of the frames' fork tube, probably starting with - 4X4
if you can post it up i'll tell you.

the scooter rear crown wheel and pinion can be swapped in like you mentioned,
it comes from a Yamaha QT50 moped, also known as the Yamahopper, or M Bop.
and has lower gearing due to the QT50 having bigger wheels
buy the complete diff unit if you can, the diff casings, crownwheel and pinion/bearings, brakes etc.
then it's a simple swap over, takes 15 mins.

there is also an aftermarket drive gear that goes inside the motor, that you can buy, it will make it accelerate quickly off the line, it costs $130 odd delivered.


milling the head 1mm will take the compression from 5.5 - 1, up close on 10 - 1, definately worth while.
and the cylinder can be bored out, to take a 44mm piston, that makes it close on a 60cc engine


the carby will probably need rejetting now that you have a high flowing air filter on it.
the Pilot jets are not very common.


check out my PW50 build thread, click on the link below in my signature.


cheers, craig

 

[ricky_191]

Yeah I just read your thread craig. You have amazing skills I might keep this one stockish so I can get a better resale. I'm putting the pit bike bars on getting it running tomorrow. Thanks for your help

 

[ricky_191]

Hi all. I didn't do much to the bike today. I mixed up a new batch of fuel and got it started. It was hard to kick it over because it didn't have handle bars on it and it was awkward to hold onto. It took about 20 goes and it didn't start so I pulled the fuel line off and no petrol come out my bad. But I turned the fuel on and bad fuel come out so that was good.

So I put the line back on and it started up and run for a few seconds and turned off. then I started it and it run for about 40sec and stalled so I left it alone. It's hard to hold the bike up and hold onto the throttle and twist it but at least it starts.

I also got all the rust off the set of pit bike bars and then primed and painted them black. It looks good but I lost a few nuts that hold the clamps on.

 

[ricky_191]

Hi all , I got the peewee going today and fitted the bars and cut the throttle cable back.. I fitted a cut down pit bike carbie spring in the carbie of the 50 so the throttle snaps back quicker. I went for a little ride and it was running good but it would stop some times but start up easy.

I cleaned it all and took a few photos

More coming soon

 

[my67xr]

i'd be a bit careful with the engine stopping whilst running, sounds like it may be running leanish
and just starting to nip up ?
if you get a chance, pull the head and cylinder off and check the piston and rings (takes about 5 mins to do)
if there is any signs of scuffing around the gudgeon pin on the sides of the piston its' running too lean.

i'm guessing, but think the standard fuel/oil ratio is 20/1.




i ran the new top end in on Cjs' PW running it at 25/1,
we have now done over 200kms on it. and have switched to 32/1.

here is a Clymer PW50 manual too if you need it.
Clymer Yamaha Pw50 Y-Zinger, Pw80 Y-Zinger & Bw80 Big Wheel, 1981-2002 - Sally F. Cutler - Google Books


and don't forget to fit some Nyloc Nuts to your bar clamps, or at least use some spring washers to stop the bolts coming loose.

 

[ricky_191]

Yeah it could have been lean. I think the fuel mix is 40-1 but I might run 30-1 and see how that goes. I'm going to get a jug so I can mix it properly

 

[my67xr]

40/1
so or 4 litres fuel and 100mls oil
or 1 litre of fuel and 25mls of oil



so to have it at 30/1
use 3 litres petrol and 100mls of oil

 

[ricky_191]

Yeah I read the back of the oil. I need a bottle to mix it in because it's almost impossible to get it right atm. Thanks mate

 

[Blender]

why not a measuring cup? measure how much fuel the tank takes, then do the oil in the cup

 

[my67xr]

the later model tanks with the air shrouds like on mine, hold 2 litres of fuel.
iirc the earlier one was a little more, maybe 2.3 litres ?

 

[ricky_191]

I don't ever finish a tank because I don't ride it much. I will get a measuring jug/cup ect next time I ride it.

Whats your thoughts on the handle bars ??

 

[my67xr]

yeah, they would help an adult rider ride it.
it's just the frames aren't really strong enough though
i have seen one that had snapped off at the steerer tube from a teenager riding it, and doing some little jumps etc.
the frames can also sag in the middle with bigger riders.

 

[Blender]

the bars are fine, bars i have always thought are a very personal thing. kinda like when your at the op shop and your deciding what underwear to buy haha. i've always liked low rise bars, high rise make my arms tired, but then again low rise hurt my back from bending down...Medium rise to the rescue!!! na mate, i like the pro taper xr 50's. there generic, everyone has em, thats for a reason.

 

[my67xr]

those bars make the bike look like it has the PitBike bar conversion that they sell at PeeWeeCycle
home page for yamaha pw50 parts peeweecycle.com

have you seen the PW50 rear brake pedal conversion too, a bit dear at $100 though
PW Only :: PW50 Parts

 

[ricky_191]

It was a fair bit of work to put them on. It is so easy to ride with them on there and it's a bit of fun. I don't jump it or go over bumps or any thing on it.. Just grass or a dirt track.

I'm thinking of selling it. It hasn't cost me much at all though so I might keep it around. It's pretty fun