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Thread: Yamaha YZ 250 EFI

  1. #1
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    12th March 2010 - 16:56
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    Yamaha YZ 250 EFI



    Some might be interested.

  2. #2
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    3rd May 2010 - 18:46
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    Great work and 10 points on the video, any comments on the power vs the standard carb at this stage ?

  3. #3
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    25th May 2013 - 18:51
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    Good stuff. Keep it up. Why arnt the factories doing this??

  4. #4
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    Quote Originally Posted by Pk33 View Post
    Good stuff. Keep it up. Why arnt the factories doing this??
    cos the fueling is only half of the problem.The biggest problem is the a lot of oil used for lubrication is burnt with the petrol,not so good for emmisions

  5. #5
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    12th March 2010 - 16:56
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    Kawasaki EFI

    Just thought it might be of interest to some people. I goes very well although we are still adjusting the fuel map. Looking to have it at trail blazer this week end for more testing.
    Should have this beast there as well, it was the first twostroke I fuel injected, first mechanical then electronic ). Oil is the least of the problems but in this video the kawasaki is running 40 to one on ethanol ( effectively 20 to 1 ratio ) a little smokey but it's only castor and it's like this for safety under testing.


  6. #6
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    Quote Originally Posted by BMWST? View Post
    cos the fueling is only half of the problem.The biggest problem is the a lot of oil used for lubrication is burnt with the petrol,not so good for emmisions
    They've got it sussed on outboards so why not bikes?

  7. #7
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    9th January 2006 - 12:26
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    Quote Originally Posted by Pk33 View Post
    They've got it sussed on outboards so why not bikes?
    apprantly it has to do with the amount of power (amps) the direct injection requires, they can get it to work on multiple cylinder out board motors, but not on single cylinder bikes, (DI two strokes tend to be only on the bigger outboard motors at this stage)

    it was said that Husqy had direct injection two strokes about to be released, I wonder if KTM has brought the rights to this technolgy,

    Sthil has released two stroke concrete cutters now, i am not sure if they are direct injection or not,

  8. #8
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    17th November 2009 - 14:46
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    Wow, looks like a winner, so will this be a retro fit as well as a possible OEM fuel system on new bikes? I know of a certain EXC 250 that might like one. Keep up the good work chaps.
    HOW DARE YOU SAY I HAVE A BIG PIPE
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  9. #9
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    Epic Events trail ride on Saturday, lots of fun.
    EFI twostroke at work.







  10. #10
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    22nd October 2006 - 00:29
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    Quote Originally Posted by scott411 View Post
    apprantly it has to do with the amount of power (amps) the direct injection requires, they can get it to work on multiple cylinder out board motors, but not on single cylinder bikes, (DI two strokes tend to be only on the bigger outboard motors at this stage)

    it was said that Husqy had direct injection two strokes about to be released, I wonder if KTM has brought the rights to this technolgy,

    Sthil has released two stroke concrete cutters now, i am not sure if they are direct injection or not,
    It was 3rd party developed I heard ( husky's direct injection ), I wonder what rpm they can get a DI 2/ up to, be pretty dang cool a di 200 2/ that could pull 12k.

  11. #11
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    31st December 2010 - 09:02
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    Does the rotary disc induction help with the fuelling ? I suspect it would as it will be more controlled than a piston/reed valve engine, now anybody got a RG500 engine to test on ?

  12. #12
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    12th March 2010 - 16:56
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    no, no real difference to fueling / tuning, but the rotary valve engine does have a stronger top end. This engine ( F9 Kawasaki ) features a sliding rotary valve housing. This changes inlet timing as the engine changes rpm so you can have late valve timing ( strong top end ) and yet still have mild timing at low speed for good low down pull ( all the advantages of a reed motor with out the top end gas flow drop off disadvantage). This sliding valve is varied by the computer driving an R1 servo motor. I am slowly building up a new engine to fit into a YZF 250 ( 0010 ). This will be a 350cc EFI, reverse cylinder, reverse rotation crank, variable rotary valve. I'm making the cases so they will fit straight into the alloy frame with no need to cut it.




  13. #13
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    23rd April 2008 - 19:15
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    Awesome man, great job!

  14. #14
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    EFI Dyno time



    First time on a dyno

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    You Sir, are my new hero...

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