This is the 2-stroke O.S. Max 28XZ Truggy Engine.***Because of the expressed racing nature of this engine, ********* it is NOT covered by the O.S. 2 Year Warranty ********* per page 8 of manual ******Features: Designed for 1/8 scale truggy applicationsAluminum crankcase, black in colorThree needle 21J slide valve carburetor8mm red carb insert for smaller tracks that restrict air intake and9mm blue carb insert for higher RPM applications and larger tracksSix port piston sleeve ensures high powerTen fin blue anodized cooling head with inner head buttonINCLUDES: O.S. Max 28XZ Truggy Engine with instruction manual, P3 turbo glowplug, 8mm & 9mm carb inserts, extra copper head shim, exhaustgasket, dust cap set and instruction manualREQUIRES: Fuel: 10-30% nitro content (20% for break-in)Air Filter: MSFG1660Exhaust system depending on vehicle, see COMMENTSTrack equipmentSPECS: Displacement: 0.284 cu in (4.65cc)Output: 3.31ps/32,000 RPMBore: 0.728" (18.5mm)Stroke: 0.681 cu in (17.3mm)Practical RPM Range: 4,000-38,000 RPMWeight: 13.2oz (375g)Distance between Mounting Holes Same Side: 0.83" (21mm)Distance between Mounting Holes Opposite Side: 1.4" (37mm)Length from Backplate to Drive Washer: 2.9" (73.3mm)Width of Mounting Flanges: 1.8" (45mm)Width of Crankcase Below Mounting Flanges: 1.2" (31.6mm)Distance from Crankcase Center to Drive Washer: 1.7" (43.9mm)Height/bottom of Mounting Flanges/top of Cylinder Head: 3.8" (95.9mm)Height/bottom of Crankcase/top of Cylinder Head: 4.4" (111.9mm)COMMENTS: The O.S. Max T-2060 WN Speed Tuned Pipe OSMG2939, OSMG2938is an ideal exhaust system for the 28 XZ.Flywheel sets are required (OSMG2648 for Mugen, OSMG2649 for Kyosho,both sold separately) for certain truggy models.Some notes on rotary and slide valve carburetors;Rotary carbs offer a larger response in the middle of the powerband. This works well for off-road applications when throttleresponse must be varied.Slide Valve carbs provide greater response at the beginning and endof the power band. This works well for on-road and racingapplications for fast take-offs and high speed.