Kirk Mayfield was a factory trials rider for Yamaha back in the day ('70's). Just recently, he decided to build a TY250 that would rival, or actually surpass his factory bike. He purchased a bike he thought was in good condition, only to find it needed a great deal of work and many parts either fixed or replaced. Other than the obvious cables, bars, fenders, etc... he made several upgrades to the TY, including a 520 chain conversion, electronic ignition, foot peg lowering kit, stainless steel head pipe for a WES alloy exhaust, boxed alloy swing arm, and of course an OKO 26mm carburetor with a vertically stretched bore. The Yamaha is now just about finished except for some cylinder and head work. Kirk's mission of building a TY better than his factory ride has come to fruition, so now the fun part of riding can begin.
The frame has been powder coated and practically all aluminum pieces have been polished.
I was honored to be able to help with carburation. The 26mm OKO has had its bore machined vertically to provide the TY with more top end without sacrificing bottom end smoothness and power.
Here's Kirk on a test ride. So far he's very pleased, but still in pursuit of the most performance he can get, Head and cylinder work are next, and that should do it.
Here's Kirk's finished bike, ready to go. He says he spent many hours polishing as well as building and even had the outer surface of the fork springs polished as well as the inside of the fork tubes. Note the alloy boxed swing arm, lower foot pegs and different shock mounts.
Here's a good shot of the WES exhaust coupled to the Sammy Miller stainless steel header pipe. I'm sure you TY enthusiasts will notice many other upgrades.