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cbr250rr derestriction

Discussion in 'Modifications and Projects' started by notorious_nick, May 25, 2008.

  1. ok guys this one has been done a million times on a million forums, but a straight answer is hard to find.

    ive seen everyone say that theres a pin in the speedo that you can grind off or bend aside, or that you can buy a derestriction box that you plug into your speedo, but these mods only affect the top speed.

    ive read of one feller doing the air filter scene and apparently removing a plate in front of the air filter to release more ponies / torque.

    my question though is how does a complianced 1990 model compare to an aus import 1994+ model?

    even though my 1990 model was originally a 45hp model, has the aussie compliancing brought it down to 40hp like the 94+ model and how do i derestrict any power restrictions, as opposed to the speed restrictions?

  2. why on earth would you bother?
  3. Why not? If he likes the CBR & wants a bit more power, why on earth shouldn't he? I had my Mito derestricted for the same reason.
  4. Best asking this on the cbr250rr forum. I wouldn't assume that the aus model is just the 45hp model with a restrictor, it may possibly have different cam profiles or some such.
  5. No, but 18 years of age will have probably brought it down by that and then some.
    If you don't know if it's 40 or 45hp then really, does it matter?
  6. There is a pin to stop you going over 180, but can your cibby do over 180?

    Apparently freeing up the air filter and new exhaust is good for an extra 5 hp. which is a 10%~ power increase! But you need new jets so it doesnt run lean.

    If its a 1990 model, then it shouldnt be restricted. Go check out the cbr250 forums, which iirc is www.cbr250.com . Nice bunch of people and very helpful. At the end of the day, you have a 250 which is extremely well designed (getting 45hp out of a 250cc when they are only just starting to get 200hp out of street 1000cc) and you won't be able to get ball tearing power differences out of it.
  7. hey out of interest take your cbr250 to a dyno...my guess is that it barely gets close to 45hpr...not dissin the bike directly but i think u will find that advertised figures are at the crank..and that would be a top notch example at that..id say a cbr250 would prob make around the 30hpr at the rear wheel..
  8. I think pro-pilot has some experience with the de-restricted cdi he bought off ebay... He said it worked quite well....
  9. IMO It's all a load of BS.

    the MC22 Aus complied cbr250rr (RY) came in via hondaMPE aust in 1996.

    I still have mine that I purchased on easter thursday (april 96).

    there are a number of aus - specific changes to comply with ADR's, including exhaust headers, CDI and hardwired headlights etc.

    Like I said, I've owned mine since new - thats 12 years and counting, and it's only got 35000Km on it. I've tried all the tricks, including dynoing genuine HRC cdi's, airbox mods, exhausts, and a truckload of other mods.

    The bottom line is simple: once you start fiddling, you lose torque. Standard au spec models are lucky to push 40 rear wheel nobbies on the dyno in standard trim. do an exhaust and you lose a few more. jet it up and you claw back some top end, but lose some mid, and it all gets peaky.
    fiddle with the airbox by removing the plate or doing the k&n filter, and you lose gas speed, and that's directly translated into rwhp.

    everyone has their own spin, but I can tell you (and back it up with dyno sheets) that every change you make brings a net loss in torque or rwhp.

    The MC19 engines have larger ID headers, and no cone baffle @ the collector, which some people swear by. the MC19 head also has slightly larger porting, but you need to take advantage of this by increasing gas speed, which is hard for an engine with such a small bore & stroke.

    Like I've said, I have seen it all - but rather than discourage you from wanting to do it, I would encourage you to learn in your own way, have fun with your baby blade like I have, and enjoy riding it and doing your own mods.

    With one caveat: Honda spent a lot of R&D $$$ on this bike as a mainstream jap market commuter bike. It works exactly as intended in this way, returns excellent fuel economy, fantastic power and handling for an entry level bike. Changing items from standard, is always going to change the way the bike behaves, and may detract from the overall rideability and reliability.
    There are not many people who still own an AU complied HondaMPE import that they bought from new, and that also means there are very few people out there who know exactly what a standard baby blade should ride like, or can tell whats exactly original.

    Have fun with your mods and your bike, keep it shiny side up.
  10. I think what Zippah says is likely to be pretty much on the money, and besides, you just need to learn to ride it like Zippah, and that extra 5hp will serve you no purpose...
  11. Hey there!

    boy have I got news for you...

    2008-04-09 Zippah turned into a temporary Superman. a low speed accident where a dumbass astra driver turned across traffic without looking netted busted ribs and left hand side contusions plus some other small injuries. Lucky for me I have really good reactions. the downside was the wet road increased my braking safety margin, and although Im careful in the wet, other people aren't necessarily so. I can say my braking effort and huge stoppie in the wet saved me from being roadkill.

    Bike was damaged, endcases and subframe took most of the smack. It is recoverable. No damage to chassis or swingarm at all. not a scratch.

    I almost cried. The baby is an emotional attachment. It's not like the other bikes I've been through.
    BUT the good news is Brendan @ SPM and Zeno are having a field day :) I've put in the wishlist, and it's all coming together nicely.

    Soon to be a (surprise) with a truckload of more mods.

    Stay tuned. You liked it before, just wait till you see it's new bits.

    I'm on the mend - still splinted up and suffering travelling to work in a cage... and can't wait to get back on 2.

    Hope everyone's well, looking forward to catching up as soon as i'm back on deck.
  12. the 1990 cbr 250 is not ristrcted
    compliencing in aus does not ristrict it
    the the ristriction for later models was done for the japanese market
    ur bike is not ristricted
    u can get a few more ponnies but its seerouse work and will most like make a hand grenade.
  13. 94+ are restricted mechanically not electronically. waste of time/money/effort to try and bring it up to 91 92 model spec
  14. I think if you give the full story they are not actually restricted as such, but through porting changes among other things, produce slightly less power than the earlier models.

    That is standard practise for Honda and others, to improve reliability and rideability.

    See motorman and his excellent porting series for the real story...



    Trevor G