BIKE OF THE MONTH: CHAD FITZPATRICK’S YZ650


Editor’s Note: I saw this bike somewhere on the internet while I was killing some time. The bike was under construction but you could easily see the potential. I sent a message to Chad and requested updates then promptly moved on. So many times I get no response, I have learned not to expect one. However, I was pleasantly surprised when one day I did have a reply; and furthermore the bike was completed and had actually been raced! Well, I was excited all over again and I hope you enjoy this as much as I have.

Chad began with an 81 Yamaha XS 650. He selected the main part of the frame, the engine and swing arm. Now the measuring began as the steering head was de-raked 4 degrees to 26.5 degrees. This of course was entirely for the quicker steering a motocrosser must have.

With the hardest part completed Chad sourced parts from a 1981 YZ125, the rear frame half, forks and front hub, seat and the fuel tank. He added some mid 80s KX 250 clamps and All Balls steering head bearings, then shortened the front forks 1.5”, kept the stock spring length, and planned for 20 wt oil with five psi air pressure up front to soak up the bumps and jumps.

Buchanan’s front and rear stainless spokes were laced to Takasago shouldered aluminum rims and fitted between the forks and swingarm which was being handled by Progressive rear shocks. Dunlop MX 33 tires were selected for roosting at will.

A bunch more little details were needed and Chad found everything to make it work.
A 1978 DT175 rear hub and spring assist chain tensioner to maintain tension and a 1979 Honda XL175 lower chain guide to help keep track of things. Sprocket Specialists sprockets 520 16/44 and an RK 520 chain were installed. 1999 WR400 foot pegs, mud flap, and chain rollers found a home there and the upper mud guard was made out of a no parking sign.

And still the list of custom fitted parts goes on. There is a 70s Cr250 rear brake cable, Chad made a custom shifter, brake pedal, and linkage. The stock CV carbs from the XS worked well enough but it was clear the motor needed better breathing and control so Chad added a pair of Mikuni 34mm carbs from Hoos Racing and lets them breath through a pair of Uni Filters. XS650 ignitions are adequate and so is the charging system, but they’re not nearly up to the task of a custom built one off motocrosser so Chad turned again to Hoos Racing for the Electrex World ignition from Hoos racing. Then, since points,condensor and advance plate were no longer needed, Chad had a set of custom cam covers fabbed up by American Technical Fabricators in Bad Axe, Michigan to narrow the engine and get a little more knee room. A custom exhaust was made with the do it yourself kit from TC brothers. Universal exhaust heat shields and 1 inch wide header wrap where pipes go underneath carburetors but no mufflers for this beast.

Finally, Chad was ready to turn to the cosmetics. He selected 1977 TT 500 side panels and a replacement front number plate for 1980 YZ 125 from DC plastics.

Chad says “It took me six months with approximately 165 hours of labor into it. I Spent a lot of time making sure the chain stays tensioned properly. My goal was to make it look like something that could have actually been produced. I also had a lot of time mocking it up with seat, sub frame and body work to get to that factory look. And best of all the bike actually worked well in the 1983 evo class.
Chad welcomes comments about his bike at: 1981yz650f@gmail.com

Thanks, Chad

If you have a bike you built and took pictures and or video of the build, send them along with a write up to mtreadersrides@gmail.com.


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