2010 Yamaha YZ450F leaked with reversed single-cylinder

Dailies -



Update: the 2010 Yamaha YZ450F has been officially unveiled and, yeah, this was it. Click here to see it.

This shot of the 2010 Yamaha YZ450F is getting a lot of attention and rightly so. We can’t remember having seen any reversed cylinder machines sold to the public since the 1990 Yamaha TZ250A privateer road-racer. Beyond the reversed single-cylinder, the new YZ450F looks to be an entirely new bike, with a slew of refinements including front and rear suspension, rear frame, new seat and we’re guessing a completely revised chassis as well. While we think the Yamaha looks pretty cool and will be fast in the dirt, we’re holding out for a  supermoto version.


The logic behind the reversed cylinder is better weight distribution by pushing the crank down and forward in the chassis for improved handling as well as a cooler intake and a direct line of flow from intake through the cylinder to the exhaust port. This was also the criteria for the reversed-cylinder TZ250, which, if memory serves right, was known to be rather delicate, cracking motor mounts and causing water pump failures, chassis harmonics and vibration issues. Hopefully Yamaha has fixed all those gremlins this time.

via MCN
  • JR

    Is the tilted back cylinder good for weight distribution?

    • Hosenpants

      MCN said: “…the inlet tract can have a straight path from fuel injector to combustion chamber thanks to the cylinder being inclined backwards.”

      This different layout brings to mind the Husaberg FE 450 – the one with the flipped engine – cool stuff. I wish I had some experience with these bikes.

    • Hosenpants

      Sorry, scratch that first bit. Shouldn’t assume you haven’t read the article.

  • Ben(pi)

    The short lived Cannondale motorcycles had a reverse cylinder set up, as well as Rob Tuluie’s Tularis. There is also an engine that Norton is looking at using in their production bikes (can’t recall the name off the top of my head) that has an option for reversing the intake tract.

  • Scott


    ok, almost had me for a second.

  • JR

    Hmm, that’s weird. I just came back to this post from my home computer, and apparently I could only read the first paragraph from work. They filter things pretty heavily there.

    Now I see why you must think I can’t read very well, based on my pretty obvious question.

    Oh well.

    • http://hellforleathermagazine.com Wes Siler

      Calm down, you’re not going crazy, Grant added some info.

  • JR

    haha! good to know

    Thanks Wes…always got my back.

  • http://www.fetherston.tumblr.com fetherston

    Smashed up header pipes have been a problem this outdoor motocross season. Should be interesting to see how the shock mount location changes; this design would allow more options than before.

  • http://setthemfree.tumblr.com Sasha Pave

    So awesome, go go Yamaha engineering!

    One correction Grant. You’re correct about the TZ having reversed cylinders, but it was the 1988 TZ250U which debuted the front carbs (my team raced them from 88-90).

    Compared to the 87, it was light years ahead on performance and marked the intro of proper sized 17″ racing wheels ready for radial rubber. I don’t remember any mechanical faults, but I had John Lassak tuning for me :)

  • Stephen Sullivan

    Whats the big deal, Yamaha seems to be copying the Cannodale 440 design that is still sold by ATK now. Everyone seems to forget that Cannondale was the first dirt bike to come with a reversed cylinder, fuel injection, airbox on top back in 2001. I have a 2002 Cannodale converted to a Supermoto that runs just fine.

  • Jon

    is the carb in front and the air-box???

  • Sandeep

    I think its a shame you support people who leaqked yamahas blue prints , should you be cursed for it ? decide yourself

    take it off

  • BOB


    • asdfasdf

      Bob, of all the words in your post to screw up, right is the worst.

  • Shawn O

    Snowmobiles have been using the reverse cylinder technology since 2003 in production machines so it isn’t new but it is to Bikes.

  • xânto

    Que será que nossa querida Yamaha está aprontando para o futuro????????

  • Devo

    wut did he say?

    well anyways, im broke between the rmz 450 this wonderful looking machine and the crf450. I dont know what to get just yet, i guess ill just have to wait and see how the tests go with this bike.

  • El Dusto

    Interesting… In this image, Yamaha has labeled the rear fender as a “new front fender.” Oh the shame!!

    Seems like the cylinder isn’t the only thing that’s backwards ;)