Yamaha QT-50 Restoration 

Although it wasn't previously documented here, this project has been going on for about 6 weeks. During this time, I've accumulated a few documents that have been extremely helpful in the process. I recommend these to anyone undertaking a repair or rebuild of one of these old bikes. These are local copies and will be available here for as long as this site is on the web.

Yamaha QT-50J Owner's Manual (1984)

Yamaha QT-50/MA-50 Service Manual

Here is a very clean example of a QT-50 (not mine):



Photos of my project bike (from Craigslist) as I originally found it can be can be seen in the gallery at this link. It was quite a mess, but I was able to start her up after only a few minutes! There are more detailed photos in "as found" condition here.

After finding a parts bike, and a few trips to eBay, the bike is much improved. As of today (July 9), it runs and rides pretty well. There are some grainy photos here. Excuse the garage clutter, I still haven't unpacked everything from the move (I know, so lazy).

If you are planning to rebuild one of these bikes (or probably any vintage moped), my advice is to try and find a parts bike as quickly as possible. I originally paid $60.00 for my QT-50, and shortly afterward had a call from someone who was selling a bike for $100.00. Of course, I really didn't want to pay a whole lot to get this going, but after some thought (and a paycheck), I bought it. I thought I was making a mistake, but I was so wrong. The parts I got from the donor bike would have easily cost me $400.00 (or more) if I had bought them separately (the main ignition switch alone would have been at least $90.00). The bottom line is that most people will not want to strip a bike down to part it out. They would rather sell it whole, which probably means selling it locally, which means the price stays reasonable. Although it's great that some of the hard-to-find stuff is available on eBay (speedometers are REALLY hard to find at a good price), the prices for parted-out pieces are kind of extreme. So save yourself a few bucks (or a lot of them), and keep checking CL, yard sales, and the classifieds. A remarkable number of these vintage bikes are still out there in the back of someone's garage waiting to get back on the road. [Just happened to think... Some of those over-priced eBay parts have been on there for six weeks, and still haven't sold. I wonder why these guys don't just get real on the prices...]

REALLY IMPORTANT NOTE: If you find a bike missing the key, but with the main switch intact, resist the temptation to try using a screwdriver to start it. You will probably destroy the switch, and the bike may not start anyway. My bike had originally been taken down this road. The switch was broken up inside, and it took 10 minutes of messing around with the thinnest screwdriver I could find to get it into the start position. The donor bike had a perfect switch, but no key. I found a locksmith on eBay that made a key using the number embossed on the switch. It cost $27.00, but worked perfectly, and saved me from having to replace the switch ($110.00 was the cheapest on eBay at the time, although I saw one for $90.00 a few days ago).

Still on the TO-DO list:

- Check out the oil pump (running 32:1 premix now).
- Get some mirrors (should be here at the end of the week).
- Replace the rear brake lever (ditto).
- Pack the wheel bearings (front and rear).
- Rebuild the front end - Pack the head tube bearings, etc.
- Replace the battery.
- Get new tubes, or maybe even tubes and tires.


I took her out for a spin last night. I believe the carb still needs a bit of adjustment (idle seems low), but acceleration to 25 mph was smooth and easy. Ran about 5 miles round-trip.

[UPDATE 2013-07-10]

Got the mirrors in the mail today. Left one goes on fine, but the threads seem stripped on the right perch. Oh well, they only had one mirror anyway, guess I'll just run "stock". Also, for whatever reason, and I'm not complaining, the battery now seems to be holding a charge (hazzah, working turn signals). Guess I'll hold off on that replacement... Also, I confess that I put Slime in the tires. The shame... However, it seems to be working, so whatever...

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