Yamaha’s answer to the recently-retired Honda XR350R, the TT350 was a hybrid between their XT dual-sport and the YZ motocross bike. Yamaha marketed it as “Dirt Tough, Street Wise” and “a purpose-built machine that’s perfect for tackling the toughest enduro…or riding to work!” They only sold it for two years, making it difficult to find nowadays.
Technology-wise, the TT350 was pretty straightforward. Yamaha went with an air-cooled motor and it made 26 horsepower. One noteworthy feature was the Yamaha Dual Intake System (YDIS): they used two carbs for the single-cylinder engine.
The Teikei Kikaki carbs utilized for YDIS.
At low-rpm, the motor was only being fed by one carb for better low-end response. At high rpm, both carbs were in play so there was enough fuel flowing for better top-end performance. You can see a simple illustration here. For more on the TT350, check out this “Classic Steel” profile on PulpMX.
This example is said to run and ride great, it’s mostly original except for new grips, a seat cover, and stickers. Check out this period ad to see what the stickers should look like (Yamaha is smaller on the tank and the TT logo is slightly different, note the “slices” in the Ts). “Bike has been serviced with fresh oil, oil filter, spark plug and full tank of gas.”
Find this TT350 for sale in South Jordan, Utah with an unmet opening bid of $3,500 here on eBay.