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Bike of the Month
January 2022
1978 Yamaha XS 750 Special
By Rick James

I bought one of these Yamaha's brand new in 1978, and then went on a 5 week trip with a buddy who also had one. These bikes are fun, fast, smooth, and comfortable with triple disc brakes and shaft drive. I purchased and installed a "Triumph bend" set of handlebars to replace the ridiculous "pullbacks", and I also installed a rear rack. I put 14,000 miles on it in less than a year, then sadly had to sell it because I was getting rained on in the San Diego winter. I needed a car.

Fast forward to 2005. I was going through Craigslist and spotted an ad for one the same year and color as the one I had. It stated, "engine seized, needs work, $400 ". I'm thinking ok, so it probably has a seized piston, that's not too hard to fix, so I purchased the XS. I squirted some penetrating oil into each cylinder, let it sit for a few days, and tried to turn the engine over with a breaker bar and socket. Nope. Wouldn't budge. I then joined an online Yamaha Triples Club and while searching through their forums, I learned about something called "gas-oil". Yamaha's of this era used vacuum operated fuel petcocks that open when the engine is running, and close when it's shut off, closing off the diaphragm. There wasn't an "off" position on the petcock. What would happen is the diaphragm would wear out, allowing gas to slowly leak past the intake ports and eventually go by the piston rings and dilute the crankcase oil. It was a big deal and Yamaha had a recall on them, unfortunately it had ended before I bought this bike. It took me several months to tear it down to find the rods had run hot and seized the bearings. I purchased a used crank, a set of rods, new rod and crank bearings, a manual, and a gasket set. I also purchased a pair of manual petcocks. These motors are very well built, the quality is amazing. The bike itself was pretty nice and had been garaged its entire life, so there was no need for further disassembly. I eventually finished the rebuild and installed it into the frame. After hooking everything up, it started right up. I stripped the gas tank and painted it the original "black gold", got a new seat cover and a set of tires. That was it, and my efforts were well worth it, I was instantly transported back to 1978 and had my new bike again. Who says you can never go back?  

XS750 1.JPG
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