Need help to fix my little guys bike Yamaha Pw-50
Posted April 05, 2010 - 04:30 PM
Posted April 05, 2010 - 05:45 PM
Posted April 07, 2010 - 03:49 AM
Posted April 07, 2010 - 03:56 AM
Posted April 07, 2010 - 05:54 AM
PW's cylinders are borable. They are really easy to work on. Pull the pipe & carb and the 4 head bolts and the head & cylinder will slide off.
Posted April 08, 2010 - 05:23 AM
Posted April 08, 2010 - 06:22 AM
Inspect the crank and make sure it's ok.
Yes, you can bore it and buy an bigger piston and maybe save a few bucks but that is a alot of hassle for the $175 it would take to bolt on new stuff.
The main issue here is figuring out what happened so it doesn't happen again. some pics would help.
Posted April 08, 2010 - 06:56 AM
1st get a factory repair manual as you will need it. With the manual and basic tools & knowledge you should be able to do the top end reb and it will tell you how to check the crank.
Take the cylinder to the local shop and have them take a quick look at it. They should be able to tell you for free if it needs to be bored or just a hone and what size the bore is now.
For a 6 pack of brew you should be able to get a mechanic to come into the parking lot and check the crank for you.
While you are there have parts quote you on a new piston, rings, piston bearing, piston pin, 2 circlips, head & base gaskets.
Posted September 07, 2010 - 07:29 AM
hi ive got a pw50 yamaha i
usually an oil related seizeure is easy to spot due to galling on the sides of the piston. the whole area that contacts the bore gets beat up.
took my carb apart and wen i put it back to gether the pin has got jammed in the carb carnt get it out can u tell me how to pull it out
Posted September 07, 2010 - 09:57 AM
Posted October 12, 2011 - 02:54 PM
There can often be a problem with the injectors on those bikes, especially in off-throttle situations (going downhill?) when the engine is hot. Throttle off = no oil. I would definitely look into switching over to premix. It's not hard to mix the gas and your kid's engine will be more reliable.
PS- the crank should turn over freely by hand when you remove the cylinder from the cases. You can have a little side-to-side motion in the crank assembly, but absolutely no up-down when the engine is at top dead or bottom dead center.