I believe the reason that Honda will only use 4 stroke engines is that the EPA is really cracking down on pollution.Look at how Polaris is slowly replacing all of their two stroke engines with four stroke engines.I even heard that the EPA already has given Mfg's a deadline.I wonder what they will do about snowmobile and outboard motors chainsaws and weedwackers.Look at all of the new fourstroke marine engines that are hitting the market.

 

Another reason is doesn't make sleds or watercraft where you need that 2 stroke power.

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Andrew Thomas

'99 Scrambler 400 & '99 Trailblazer, both with RCR mods.

 

Honda is a 4-stroke engineering powerhouse. Look at what they've done in European F-1 car racing and here with CART - absolutely kicked butt. All with 4-stroke. Their newest 4-stroke CBR929RR makes over 160bhp per liter in EPA legal trim.

They win with 2-stroke also - see the success of the World GP bikes and Mick Doohan. But its nice to "win on Sunday, sell on Monday" and nobody is selling a 2-stroke street bikes in the US (over 50cc) because its so expensive to clean up the emissions. Its rumoredthat World GP is planning a switch to a 4-stroke formula. Even Honda's latest 50cc scooters in Japan now have a liquid-cooled 4-stroke with 12:1 compression!