Yamaha QT 50 "Noped" project

[Rat Rod]

Sounds like you just need to fly outskirtscustoms in for a weekend to finish the project. :lol:

 

[outskirtscustoms]

Sounds like you just need to fly outskirtscustoms in for a weekend to finish the project. :lol:

:lol: Well I'm not an expert on them but I used to work with a friend tinkering on mopeds and scooters rebuilding them. Probably 300+ mopeds / scooters a year (Every few days we were getting something new to work on sometimes 4 at a time) for 4 years straight year round. I have seen everything from people using motor oil instead of 2 stroke oil to the Chinese 4 stroke motors, to wrecks, to complete basket cases from the early pedal type to no-peds to scooters, to even a few motorcycles. Most of the scooters I did were quick flips though, buy them ugly and do a quick re-spray and tune up then sell it for a few hundred profit, others were build it from scratch and make it run to sell it cheap, then there were a few really nice ones. I've worked on about every make and model from Honda, Yamaha, Sundiro, Geely, batavis, trek, trac, Motobecayne, you name it.

Here are a few scooters I worked on, a few still haunt me like the Yamaha Chappy I mentioned before
"Swamp Thing"


Here's one that was so ugly you had to love it. Yes the body work is a old board, mud flap, and the bottle was nessisary to start it... Give it a drink of fuel and away you went.
Before



After


A regular day was to do something like this
Before

After


My old camo seat razz


Then there were bad days




Few others














One of my personal favorites

 

[outskirtscustoms]

Also a word of advice to all of you thinking about a moped, no-ped, or scooter, A Honda Urban Express is the biggest headache I have ever seen in working on hundreds of models, the kick start mechanism sucks, the vacuum choke never works right, and they are a pain to find parts for. They look cool but they are a huge headache.

 

[Whitfield]

Re: Yamaha QT 50

Why would you lose the lights going with a CDI?

You don't have to ...
The PW 50 does not run a battery and the charge / lighting coil is not in play (But most likely ~ with mass production it is still there). Wire it up and run a stock Yamaha regulator AC or Rectifier Regulator battery DC and you are good to go. Many of the small CDI ignition bikes run headlight / tail light, some even do it AC / battery-less. The electricity does not care what style engine is turning the flywheel.

 

[Whitfield]

Link to roll your own lighting coil on a CDI bike. While the XR100 is no QT 50 ~ there are many electrical similarities with the PW-50

http://home.comcast.net/~pgailunas/stator.html


I noticed in the parts manual it says the pw50 has a lighting coil... So looks like lighting power is already there stock along with CDI.






I know a guy, who knows a guy, who's niece used to ride a PW 50...

 

[yoothgeye]

And I know a guy who has a niece who's dad can explain why that Z50 has a clutch lever.

 

[dracothered]

yoot watch out for those clowns over in Moped Army if you do anything that falls out of their narrow view of what a moped can be the idiot come out of the wood work.

 

[yoothgeye]

No worries, I play nice with others.

 

[dracothered]

No worries, I play nice with others.

Wasn't saying you don't play nice, it is them over there... or should I say the few over there that have a narrow view and don't play nice.

 

[yoothgeye]

OK, I put some windows in the house today but managed a few minutes in the shop while Donna was giving the kids their baths.

I was impatient again, so I removed the head nuts (that's what I'd call them) and removed the head, pretty simple:

After seeing the crusty piston top I added a little heat (propane torch) and some gentle persuasion with a ball peen hammer. I gently pried up on the bottom of the head (jug?) with a pickle fork while lightly tapping the piston with the hammer. It stared to move pretty soon and as it got deeper in the cylinder I put a BMX axle peg on the piston and tapped on that while still lifting the head with the pickle fork.

Soon it popped out.

So... now what? How do I examine the rings (they move freely and are not broken) or do I just order new rings? Can I clean the cylinder wall myself or spend a few bucks to have it done? I like doing stuff myself, but if it calls for a pro, then I want it done right.

The piston moves easily and smoothly on the rod and the rod smooth and easy on the crank. I pushed down the kick start and the crank turned.

 

[Whitfield]

Next step is remove a wrist pin wire C-clip from one side, Remove the wrist pin, piston and wrist pin bearing. Then CAREFULLY remove the rings. Clean the piston / Clean the rings. Clean the cylinder as best you can, Kerosene and a dark red 3-m scotch brite pad work well. Some guys tape a piece of a 3-m pad to a legnth of somthing chucked up in a drill to spin the 3-m pad to clean the cyl.

Last one I did we were still at the shop and had the Bar hone set. We took it .020 over using a bar hone.

With the Cyl and piston clean you set a bare ring in the cylinder and push it down even with the piston placed in the cyl upside-down. Most of the wear will be at the top (Most powerful part of the power stroke / highest compression = most wear). With the pistn ring in place you then measure the ring gap. In the manual you should have a ring gap spec window. If it exceeds this window then you need rings. General rule is that you do not ever reuse rings on a 2-stroke. The piston rings are a wear item. On many dirt bikes it was new rings every year and a new piston every other year. The pistons and rings are made soft and made to wear. The Piston will wear the bottom front and bottom back of the skirt (check the piston for the bottom rocking back N forth in the bore ~ it should not).

That QT-50 being low compression and lean burn for fuel economy I'd bet that unless you have cylinder wall RUST pitting you can prob get away with Fresh piston and rings in the bore you already have.

 

[Whitfield]

If you carry the piston / Rings / Cyl to your friend at church who works at the MC shop. He can give you a hands on once over on the finer point of what to do / what to look for. Most of these folks enjoy sharing there knowledge and passing it on ~ especially when it doesn't involve getting dirty for free. He may have a better recommendation on Cyl cleaning too. You have to use some caution around the intake / exhaust ports. Nick up a port and you can hang a ring.

 

[Whitfield]

Fill the crank case with marval mystery oil and turn the crank. It needs to be ultra smooth ~ Those bearings are only oiled by the gas and oil that the engine burns. Cranks case seals are the life of the motor. New crank case seals are a step you will never regret on an older repair. AS the piston goes up compressing the mix / the bottom side creates suction and pulls the new charge under the piston through the transfer port (hole in lower intake side of piston). Bad crank case vacuum make it hard to start and run poor good crank seals = good vacuum.

 

[Whitfield]

http://www.thumpertalk.com/topic/592687 ... pw50-2001/

 

[outskirtscustoms]

Looks like she was pretty gummed up, you got lucky in that the piston was up at the top so the rust was contained to that area, if you can, get it honed out and put a NEW piston and rings in. I have done a few that I just cleaned and stuck back in because I was selling it and just wanted it to run but being this is YOUR personal ride it's not that expensive to buy new so while you have it apart I'd do it right the first time and you won't have to do it again.

Normally a new piston and rings are $20-$25 so it's well worth the investment. Also get NEW C-clips!!! AND ORDER EXTRAS!!! They will fling across the shop and you'll never find them again and if you try to re-use them after they've been bent stretched or just old clips or don't get them seated in properly they can come out and gouge the cylinder wall then it's game over. Take a large screwdriver that is about the size of the wrist pin and tap it back and forth a few times against the clips to make sure they don't come out before you put it together and seal it up. Also be careful that if a clip flings during installation make sure that it did not get into the cylinder head's intake port. I had that happen once and it totaled the head and brand new piston I had just put in the first time I revved it up.

 

[yoothgeye]

At church this morning I saw my friend that works at the local motorcycle shop (and has for a long long time as their head mechanic) and showed him the photos of the piston and the cylinder. Before I asked anything he said "I've got a hone, I'll hone it for you." Sweet! Then I asked how clean I needed to get the combustion chamber on the head, he said "Bring it, I'll sandblast it for you." Score!

Things are progressing quite well. Too bad the shop is closed mondays... of course, he has the key and sometimes goes in to do catch up work on Mondays by himself... maybe tomorrow is my day!

 

[dracothered]

Cool... hope it works out.

 

[outskirtscustoms]

Cool, good deal!

 

[yoothgeye]

Handed over the piston w/ rings, cylinder and head, he told me he'd take care of it. Easy peasy. He is a really great guy, maybe 10-15 years older than me, always been a motorcycle mechanic, has helped me out plenty of time. I get use motorcycle tires from him to test on different sized bicycle rims, and he has found me quite a few bikes for free and even a free Yamaha Wavejammer!

 

[yoothgeye]

Here's some QT50 potential: http://www.youtube.com/watch?v=RKlrygX31Fo

This I copied from his comments:

"You can buy the YT60 top end, piston and rings from Yamaha still. The PW50 gears you can buy on Ebay for the cheapest, the PW80 carb from Yamaha (needs to be rejetted). The YT60 oil pump from ebay or Yamaha. Uni Pod filter I bought from a local motorcycle shop.

NGK BP8HS spark plug. Very important or you can burn them down with too hot of a spark plug."