Honda ATV : TRX450R / Sportrax 450R ATVs

Powerful purpose-built Honda ATV four-stroke 450cc liquid-cooled four-valve Unicam engine is based on the award-winning CRF 450R motocrosser's.
Compact, lightweight engine designed specifically for ATV usage is worthy of its CRF heritage.
Unicam valve train provides the light weight of a compact single-cam drive and the optimum combustion chamber shape for maximum power at all engine rpm.
Unicam valve train features a carburized single camshaft that directly actuates two 36mm steel intake valves. The camshaft exhaust lobe actuates two 30mm steel exhaust valves via a forked, low-friction roller rocker-arm.
Lightweight, compact, internal auto decompressor provides superb cold-starting and hot-starting operation.
Engine incorporates ATV-type forward kickstarting for ease of starting and light weight.
Crankshaft is made of high-strength, low-carbon steel with carburized main journals for maximum durability at sustained high-rpm operation.
Cylinder head cover is made of magnesium to reduce engine weight.
Cast 10.5:1 compression piston features 28.4mm piston skirt length, with three piston rings for added durability.