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CBR125? RS125? Yam R125? SUPERCHARGE it

Discussion in 'Modifications and Projects' started by loki, Feb 23, 2008.

  1. this is probably going to be one of my stupidest ideas, so brace yourself. in fact, anyone with a proper bike might do well to leave this thread now.

    it's pretty daft to want to throw much money on your learner bike, but for some of us motorcycling has never been a very logical passion.

    i had one of those dangerous what-if thoughts a while ago, while watching the Peugeot Jet Force Compressor scooter race a suzuki swift around a racecourse on Top Gear. this is a supercharged and intercooled 125cc 4S scooter. 1 bar of pressure, supposed to add 60% power over the NA model scooter

    these sort of results would see a 125kg RS125 poking out 50hp for i'm guessing, around a grand.
    engine reliability would obviously go to shit, and i doubt there's any easy way to tune the carb properly, but 125kg and 50hp is some damn good maths. you'd have to save a toy like this for the weekend, but it's a very distracting concept. i know there's already turbo kits out for the old CBR250s

  2. Mate, what a wicked idea. Do it! I'm baffled as to why there's no commercially available supercharged bikes.
  3. I'm not aware of any true boosted 2-strokes. A few companies have fitted blowers to commercial 2-stroke diesel engines (GM, Foden, Commer, oh and Napier with their Deltic engine for a really big example) but those were to provide scavenging when not using crankcase compression.

    I'm not sure of the reasons for this omission, but in a field where pretty much everything has been tried at least once, I suspect that they're compelling.

    I also suspect you'd be lucky to get a successful result for a grand. A thousand bananas doesn't pay for many engine blow-ups when you get it wrong.

    If you're really set on spending a fortune on making your bike impractical, give Stan Stephens in the UK a ring (not sure of any 2-stroke tuners in Oz) about one of his stage 3 porting jobs.

    Don't want to piss on your bonfire. Wacky tuning jobs on little bikes are great fun. I think pushing your RS out to the limit could be a hoot. I'm just doubtful about blowers on strokers and think you'd get results more cheaply and easily by more established means.

    On a broader note, like Loz I'm puzzled as to the lack of supercharged bikes. Maybe it's 'cos the Japanese made all their early '80s turbos so terribly disappointing. They almost seemed to do it on purpose.
  4. That's because to get a S/C to work on a 2-stroke you have to get the engine timing right to make 100% sure the exhaust port is fully closed before the inlet - otherwise you just force fuel/air straight through. This reduces the efficiency of the engine which makes the gain from the S/C not worth the effort (especially since it uses power and adds weight).
  5. it's only a medium-sized pit at the moment. perhaps i'll leave it that way :)

    ever read about the SuperSqualo?
    same production concept as the Bullet SS Roadster cars.
    Australian company recieves Ducati, adds some Sprintex supercharger goodness and knocks it out to us happy punters
    pricey though. from memory like 40k. but it gets you 200hp in a 180kg package, with rear-facing camera and video screen for a rear vision mirror

    sounds like a right pain in the ass.
    think i'll stick to a simple bore-kit at my next top-end rebuild (in between saving up for a proper bike)

    should still be feasible for the four-stroke CBRs
    so if one of the kids on their CBR125 wants to give this idea a crack, i'd be more than happy to be surprised at the traffic lights

    thanks for your comments and input guys
    i'll lay this one to rest
  6. How much would u be looking at for a big bore kit?? What size?? and what brand??
    I am due for a top end re build soon and am interested in a little more performance as well.
  7. the Polini 154cc is a popular choice. just saw it posted for 299 pounds ($600?) plus fitting, you get a few extra horsies (i'm guessing 5-10hp) for free (i paid 800 for my 12,000 rebuild)
  8. The Super Squalos are more like $75k, and they are only producing 99 IIRC, so it's hardly a rebuttle to Loz's point.
  9. perhaps...it wasn't meant to be rebuttal,
    more of a 'btw, here's the closest thing we'll ever get to a proper factory-release forced-induction bike' mixed with some 'here's some quirky little outside-the-square eye-candy to brighten your day'
    but thanks for your small contribution to the subject anyway.
  10. try www.pjme.co.uk he has his own 144cc kit

    paul knows his stuff or you can jump on

    trevor sells BBK kits and there are plenty of people on the forums that already have them.

    i'm looking at getting a 34mm carb then BBK btw
  11. I'm still here. :p
    There's a whole host of LAMS bikes that already do this.

    How about 113kg, 60hp? Husaberg 650. And that's with buckets of torque and just as much flickability as an RS125. You've got the Husky 510, KTM 525, Prilia 450/550.

    Having said that, I love seeing a ridiculous project brought to fruition by a nutter with not enough sense to know better, but enough determination to get it done. And I say that with utmost respect. :grin:
  12. i'm yet to be bitten by the motard bug
    (only a matter of time, though :) i used to love hopping up gutters and down stairs on my mtb)
    the new ktm RC4 is posting some similiar p/w stats, might start checking out the motards after the sports bikes have done my back (and licence) in

    as for nutters not knowing better, have you seen the current fad of bored mechanics bolting the prilla 550 engines into an rs250 chassis?
  13. neat sites

    interesting, advises against the polini saying it doesn't like to rev
    $900+shipping+fitting for bore kit, manifold and 34mm carb.
    out to put some zing back in your bring-ding :)

    my brain is telling me i'm a damn fool for throwing more money at this bike
    but it's so pretty, it's hard to stay mad with that face
  14. in fitting your arrow kit, did you ditch the cat converter?
    that must have saved like 4kg, right? go much better?
  15. I was looking at trying to organise a 2t spanner day it would be good to have someone well versed in 2t engines to be able to help us out with projects like these.
    i was thinking of a Tyga can and expansion chamber Wiseco piston 34mm carb and race crank.
    Would there be any point in getting a 34mm carb without a big bore kit??
  16. I've seen just the one, but very nicely done. Great combo. I will definitely end up owning an SXV, but even with the extra horsepower, they don't pull your arms off like a big single does out of the corners.
  17. would it not make more sense to add a small-ish turbo? bit more efficient, maybe easier on a single or twin pison though i guess
  18. Not so good on a 2stroke.
  19. sorry didn't realise it was 2 stroke discussion...

    anything forced induction gets instant cred unless it blows up quickly