my new/used Yamaha PW50 thread

[Rodney68]

LOL sounds like the way to go matching coloured bikes twins LOL

 

[timeeh]

great thread!

thats it.. im getting my boy a PW50!

One step closer to his YZ?

 

[Rodney68]

LOL thats it Hillz will not be long and before you know it he will want to ride the YZ.

 

[my67xr]

look what you can get for the PW50 too, it's got your name on it Hillz
http://www.gumtree.com.au/s-ad/well...t-system-for-yamaha-pw50-not-bike-/1017193248



there are also things like Boyesen reeds, bigger carbys, 60cc barrel and head conversions etc etc

 

[Hillz]

deff need one of those!

 

[my67xr]

http://www.ebay.com/sch/i.html?_odk...3.m570.l1313.TR0.TRC0&_nkw=pw50+race&_sacat=0

FMF even have 2 different mufflers available for them.

 

[my67xr]

i have just been down and picked up the freshly bored barrel, it now measures 40.5, instead of 40.25 ,
the PW is now a true 50cc, actually a 50.5 cc to be exact.
it looks pretty sweet, time to start reassembling it now


i have borrowed my sons phone while he is out, so the pics should come up a fair bit better too.

you can see my quick port work, i opened up the exhaust a bit, and straightened the runners,
same with the intake, took a bit out of the corners, and any casting dags etc, and a couple of mm's of the bottom of the runner (short return) to help it flow a bit smoother.




exhaust port,






and the inlet port,






the 2x side ports didn't look to bad, so i have left them as is for the time being



cheers, craig

 

[Rodney68]

Top job on the ports Craig it will be good to hear how it goes now.

 

[timeeh]

Port n polished PW, cool stuff

 

[Hillz]

i have just been down and picked up the freshly bored barrel, it now measures 40.5, instead of 40.25 ,
the PW is now a true 50cc, actually a 50.5 cc to be exact.
it looks pretty sweet, time to start reassembling it now


i have borrowed my sons phone while he is out, so the pics should come up a fair bit better too.

you can see my quick port work, i opened up the exhaust a bit, and straightened the runners,
same with the intake, took a bit out of the corners, and any casting dags etc, and a couple of mm's of the bottom of the runner (short return) to help it flow a bit smoother.




exhaust port,






and the inlet port,






the 2x side ports didn't look to bad, so i have left them as is for the time being



cheers, craig

i dont think 50.50cc is correct, they are standard at 49cc 40mm, .5mm over size would not be that much of a cc gain

 

[Hillz]

just checked.. it would be exactly 50cc now at 40.50mm

 

[my67xr]

guess it depends on what calculator you use

40.5mm bore, 39.2 stroke
http://www.bgsoflex.com/cgi-bin/dis...m=40.5&osize=0.0&stroke=39.2&mode=Millimeters

 

[Hillz]

lets say its 50.25cc haha

 

[my67xr]

yeah, they are 49.3cc standard

 

[my67xr]

i have been trying to suss the compression ratio for it,
the standard motor has a 6-1 compression ratio.
since i have shaved the head 1mm, im guessing it now has around 10.5-1,

i'll be running it on a premium mix with Shell advance 2 stroke semi synthetic oil at 40-1 ,
not that i use anything else.

 

[my67xr]

Port n polished PW, cool stuff

^^ yeah timeeh, but minus the polish,
for now that is !

 

[my67xr]

i've just had a go at burning the carbon/oil from the expansion chamber, it's got a bit in there.....
but there's too much smoke for today, i'll have to wait for a windy day so all the neighbours dont choke.
here are some of the loose bits that came out when i tapped it with a hammer.
a couple of the bigger bits are almost 2cm across, easy to see how they block up and restrict the flow.

 

[my67xr]

 

[my67xr]

i am having a play around with some scrap steel atm,

 

[my67xr]

i put the PWs' engine back together yesterday arvo,
no drama's there, gave it a few kick's and she came to life,
it chuffed a bit of oily smoke out for the first minute due to the oil i put in the bore, rings, piston and bearings etc
and then started running clean, it definately has some compression compared to before.
the rattly piston noise has gone too.
the choke cable needs replacing, was a bit dry and stiff, and the inner cable is now a 2 piece.
i might have something i can replace it with and adapt it to work.
the exhausts' sound has changed a little too, most likely due to the part clean out it's had.