my new/used Yamaha PW50 thread

[my67xr]

I found someone local to weld a mounting tag onto the muffler and resprayed it.
Then painted the exhaust wrap yesterday morning and fitted the full exhaust back on the PW, ran it for a about 20min's at different rev's to bake it on.
It's dried really hard and hold's the wrap on firm.

I gave the bike another run in the afternoon and wasn't happy with the main jetting, so i pulled the carby off and when i took the fuel bowl off the base gasket cracked and fell apart.
Today i got some gasket paper and made another base gasket, and tonight i found a bigger main jet (#65) so put the carby back together and back on the bike.

Picked up the seat yesterday too, and got a cover for the bar pad made in the same blue leather.
Also changed the tank sticker's a bit, cut the stripe's off the bottom and lowered them
And i fitted the rear mudflap that i made the other night to keep thr air filter clean and dry.
Here's how it stand's now.

 

[Koper25]

That is the toughest PW I've ever seen lol. Black heat wrap looks sick.

 

[my67xr]

The last couple of time's we've had the PW out it hasn't been running to well.
It's been lacking on accelleration, no torque to get it up and going.,
I've tried rejetting it to suit and have it a little better.
I pulled the reed valve out and found that the Carbon reed i fitted age's ago has started fraying on the tip's.
This has made it lose compresssion and it's been running pretty rich.
I tried sourcing a new reed petal or complete reed valve set from Yamaha but there's not a dealer in Australia that keep's them in stock, it's a 2-3 month wait from Japan.
I've gone with a Chinese one now, it arrived today, just need to check the gap and i can fit it.
Hopefully it regain's dome torque.

I found a PW50 big bore kit (44mm piston/bore) complete with a new reshaped head on my local Gumtree today too.
The guy bought it and fitted it to his daughter's PW50 that he'd picked up cheap with low compression, but it still wouldn't start.
He said he noticed some noises from the gearbox as he kicked it over so pulled the engine out and took the clutch cover off.
He found that the clutch had exploded and bit's had gone through the engine, i reckon that's why he got it cheap.
So he swapped the original top end back on to it, refitted the engine, and sold the bike (minus the bbk)
I picked up the big bore kit for $80 including delivery from the other side of town, so saved a bit there.

I have repainted the barrel and head this afternoon with gloss black engine enamel as the china paint job was pretty thin.


These ^^ both should give the little bike some get up and go now.

 

[my67xr]

New top end is on.
I centre gapped a new Ngk BP6HS spark plug for it and fitted that
I started the bike up and it fire up second kick, smoked a little as it warmed up.
Sounds a little deeper now.
Once it was warmed up i adjusted the mixture screw to get it running the best, ended up at 3 turn's out.
So i swapped in a #22.5 pilot (was last running with a #40) and retuned it, the mixture screw is now at 2 full turn's out so i'll fit a #20 pilot tomorrow
Then suss out the needle clip and main jet.
Atm i'm in the process of fitting the new reed valve.
It's made a big difference to the take off so far though.
Here's a quick video

[video=youtube;mTsTBwbVQ5M]https://www.youtube.com/watch?v=mTsTBwbVQ5M&feature=youtu.be[/video]

 

[gottagetacheaperhobby]

Nice! Reckon it will pull cj round the track now?

 

[velociraptor]

The top end looks similar to my minarelli minus the boost port I have and sizes

 

[velociraptor]

Craig for reeds on my motor I used some boyesen power reeds for a kx80 and took only the smaller inner reeds boosted my power a bit I mean I didn't buy em I had em laying around but maybe u may be able to find a set somewhere that fits up? All I had to do diff was carve the screw holes inwards 1mm or so with a dremel worked fine. Mine is prob not the same as yours but the idea is you may be able to retrofit if you want name brand but try it with a used set first that and similar tension

 

[velociraptor]

Yeah mine is similar but I have two sets of reeds

 

[Justin82]

Great build series, pity photobucket had to ruin great posts like these.

Just finished a pw50 for my son, no where near as involved as your build, just carbie, steering stem bearings and throttle housing switch.