Looking for high hp, low weight 500cc engine

Discussion in 'Some Assembly Required' started by anonny, Dec 18, 2011.

  1. anonny

    anonny What could go wrong?

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    Looking for opinions .....I have another project in mind, I'd like to find a medium displacement engine that puts out 75-80 hp. Turbo charging is definitely an option :evil fuel injection would also be a plus.

    Weigh is a concern but I'd probably stay with a 4 stroke liquid cooled single or twin and must have electric start, something common would be a real bonus with the ability to pump in some extra hp.

    Any good ideas lads?

    If this flies I will keep it as a build thread :deal
    #1
  2. Grainbelt

    Grainbelt marginal adventurer Super Moderator

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    The EX500 motor puts out a supposed 60hp at the crank, and they are abundant and cheap. Not sure what the block weighs. They've been used in the KLE500, Vulcan 500, and EX500 in various states of tune.

    Beyond that, a 450 MX bike is probably the lightest, and they all put out about 50hp. newer ones are EFI.
    #2
  3. Hayduke

    Hayduke ///SAFETY THIRD/// Supporter

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    KTM RFS motor (400, 450, or 525?) Common, and people build them to over 600cc's. :dunno
    #3
  4. anonny

    anonny What could go wrong?

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    I have an 06 KTM 450 XC as a project base.... but I need that 75 - 80 hp :evil

    Stock it more like 50
    #4
  5. Donkey Hotey

    Donkey Hotey De Jo Momma

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    You'll have to share more of the project goals to get better suggestions. That's a lot of HP for the displacement.

    The only thing I can think of is a high RPM tuning an Aprilia RXV550 and that's going to be big bucks to pull out a perfectly good engine.

    HP--in any engine--starts with the head(s). If the head won't flow enough air, nothing you do with the rest of it will matter. I think that's going to eliminate many of the low-buck choices.
    #5
  6. anonny

    anonny What could go wrong?

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    Ok..... I put together this Timbersled kit on my 450 xc and although it's an absolute riot to ride I want to up the ante... was thinking building something with a little more whompa over the summer and keeping this for the dirt or just sell it as i already have a dirtbike I like.

    Was going to try and find an aluminum framed dirtbike such as a WR 450 and do an engine transplant and shoot for the 75 hp mark.

    [​IMG]
    #6
  7. Donkey Hotey

    Donkey Hotey De Jo Momma

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    [​IMG]
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  8. malokam

    malokam Been here awhile

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    Stock EX500 puts out 54BHP if I am not mistaken. Even with all the performance mods, it might go up to 60.
    And there was this guy who did a Nitrous kit on his drag bike (at EX500 forum) that gained like 10 HP.

    I dont think that meets your criteria.

    Though, I donno the exact weight, it should be light as the bike itself weighed like close to 400ish wet.
    #8
  9. LukasM

    LukasM Long timer

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    I think you will want to start with a high performance single that can be opened up, think KTM RFS/XC4, Husaberg 550/570/650 etc. The Aprilia twin makes great power as well but I doubt it will fit a single cylinder frame well.

    If you want something that will drop into your current frame keep an eye on the Flea Market, I am going to list this baby soon. 600cc RFS, lightened SXS stroker crank, long rod kit, custom piston, head ported + SS oversized valves, custom cam, etc, only the best parts were used and it was built by the best - GWR in Belgium. 0 hours on it, never installed. Only selling as I got a factory ride for 2012...

    [​IMG]
    #9
  10. JAB

    JAB Unsprung Weight Supporter

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    I know you said 4 stroke and e start, but how about a Banshee motor?
    Build them up to your goal pretty easy. Would sound good too.
    #10
  11. anonny

    anonny What could go wrong?

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    The EX sounds like a pretty good lead...... is anyone turbo charging them?
    I will look harder at the Banshee, keep the good ideas coming lads :D
    #11
  12. Dryslick

    Dryslick Been here awhile

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    Have you ridden a KTM 570? I have a 2Moto on my '07 450 XC, and it is a hoot, but more power would be nice. I rode a Thumper Racing-kitted 570 SX a few weeks ago, and I thought it put out a ridiculous amount of power.
    #12
  13. FlySniper

    FlySniper Bleh...

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    The stock EX motor has been pushed about as far as it will go (HP wise) and stay together. I don't think you could get 70hp out of one for very long, if at all. Forget about turboing one!
    #13
  14. Pezz_gs

    Pezz_gs Cant ride for crap

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    These look lovely, I would like one in a bike, but dont think they make them any more, Godden Engineering

    [​IMG]
    #14
  15. anotherguy

    anotherguy Long timer

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    Lightweight and powerful 500CC just screams 2 stroke. CR500 can put out mid 80s. I've heard of 90+ but that may cross the maintenance line. The primary issues are vibration (balancing helps) and starting if you're a smaller guy. They're everywhere,reliable,parts are reasonably priced and available. What exactly are you heading for?
    #15
  16. LukasM

    LukasM Long timer

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    If the price can be sorted shipping is not going to be the problem.

    The engine should make about 70 HP - reliably. It weighs 70 lbs with kick and electric start, so about half of an EX500 or 650 twin.
    #16
  17. Hayduke

    Hayduke ///SAFETY THIRD/// Supporter

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    Oh my. :knary :tb
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  18. anonny

    anonny What could go wrong?

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    ??? I don't understand the question
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  19. sailah

    sailah Lampin' it

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    Any reason to not just get a sled?:lol3

    I'm sure the timbersled is cool but that's a lot of work to shoehorn in a motor just for that one project.

    Believe me I'm not talking you out of it:evil, just wondering if all that time and money could be easily fixed with a decent sled. Speaking of that, how about a sled motor? Any 500cc twin will get you your power needs, plus the clutch is already sled made.

    I met a guy this summer that was putting a 500cc yamaha sled motor in a cafe racer.
    #19
  20. mtothef

    mtothef Been here awhile

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    what he said ^^^
    #20