The Yamaha YZ250 is a two-stroke motocross race bike made by Yamaha. It was launched in the 1970s, and has been regularly updated since.
The YZ250 has a 249 cc liquid-cooled two-stroke reed-valved engine with a YPVS Exhaust valve for a wider spread of power. The engine produces a peak 48.8 horsepower (36.4 kW) at 8,800 rpm and 30.6 foot-pounds force (41.5 N·m) of torque at 7,500 rpm, with a 9,000 rpm redline.
Since its introduction in 1974, the YZ250 has had a single backbone steel frame. For the 2005 model year, however, the YZ250 has a new frame made entirely from aluminum, which brought the dry weight down to 212 lb (96 kg), and more recently in 2010, to 211 lb. The bike has a Swingarm rear suspension system with more than a foot of travel, as well as telescopic inverted forks with 11.8 inches (300 mm) of travel. Front and rear hydraulic disc brakes round out the YZ.
The YZ 250 is a great dirt bike that has been around for a long time and will be around for a while to come.
YZ250 Two-Stroke Rebuild
After a piston meltdown and a damaged cylinder Dirt Rider used Millennium
Technologies and Vertex Pistons to rebuild a 2003 YZ250 two-stroke. Test
rider Ryan Orr spins the wrenches and overall looks just plain awesome.
www.dirtrider.com, www.mt-llc.com, www.vertexpistons.com
1987 87 Yamaha YZ 250 Rebuilding
A totally rebuilding for a 1987 yz 250.
We had to change the right inner case which was craked, to repair the Exhaust system, to check the carburetor,
to clean all the mechanical parts, change the bearings, add a new sprocket,
rebuild the stator with new coils, clean the flywheel, replace the clutch
and check the power valve, adjust the rear brake and also giving a general
EFI YZ250 Dyno Run
YZ250 with electronic fuel transfer port injection fitted.First time it's
been on a Dyno, so all
tuning has been seat of the pants.Good first effort. No ignition trace was
available on this run so we used road speed only.