Mike Finnegan’s Garage usually features crazy project cars, cool trucks, and hopped-up boats, but he recently decided to shake things up and put out an episode featuring his classic 1994 Yamaha SuperJet.
More than a decade ago, Mike traded a 50cc Honda pit bike for the 2-stroke stand-up ski, and after working out some electrical demons and rigging up a replacement steering cable, he has ridden it hard without much more than basic maintenance.
Mike kept the 1994 2-stroke “Square nose” SuperJet basically stock with the exception of a Solas impeller, an upgraded ride plate (to reduce porpoising), and an occasional coil pack. Recently, however, the ski began to have some mechanical trouble and Mike decided it was time for a proper rebuild.
He called in Mark from Erickson Machine and Performance to turn his 28-year-old SuperJet into a bonafide hot rod. Ericson Machine focused on reliability when building out this ski, going to the newer style 701cc 62-T engine that came stock in the newer Yamaha “round noses” until they went 4-stroke.
The teardown of the ski went pretty quickly, with the guys knocking it out in just over 23 minutes. A snapped engine mount bolt ate up a ton of that time as the guys wrestled with the snapped stud. With the ski finally stripped, it was time to begin the rebuild from the jet pump forward.
Erickson installs the jet pump first, so that the input shaft can be properly aligned with the intermediate shaft and then with the coupler on the engine. Proper alignment and shimming are critical, and Mark takes his time to do it right. The new jet pump has a bored exit nozzle, a blueprinted and ported body, and additional cooling ports.
The new Solas stator also features a full stainless-steel body which reduces the corrosion and swelling common between on the aluminum housing and stainless wear ring of the stock pump. An upgraded cooling system includes dual channels, and a Stinger valve at the rear of the craft- which will open and close to fill and dump the water box- increasing bottom end power and torque.
This build also has a polished and tuned Factory Pipe B-pipe specially formed and designed for the SuperJet, as well as custom port-work and a billet head girdle to strengthen the water jacket and head. Forged 84mm Wossner pistons and a modified stroke length will allow the improved engine to produce about 130 horsepower.
Mike and guys get the ski in the water and fire it up for the first time. After running and revving the engine for a bit, Mark does a plug chop- a critical step in tuning 2-stroke engines. After making some adjustments to the carbs and leaning out the fuel-air mixture, the ski is ready to ride!
Despite nearly 30 years of hard service, this classic 2-stroke “square nose” Yamaha SuperJet has been given a new life as a 130hp stand-up hot rod any freestyler would be thrilled to ride.
