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CBR250RR track bike conversation

Discussion in 'Modifications and Projects' started by POPEYE, Sep 25, 2013.

  1. hey guys,

    I recently decided to 'retire' my cbr250rr to the track.

    I am applying to join a club & get my MA license so I can do practice ride days & maybe race in a classic era series just for fun.

    Just had a couple of specific questions:

    1. whats the best shop to tune this bike (Sydney Area), it has four carbies & its a pain to balance, i know that, but it definitely needs a proper tune as the previous owners have installed a non standard pipe on the thing & got knows what they have done with the carbies. I was thinking of maybe approaching RB Racing as they originally imported this bike?

    2. The front forks are quite bouncy, however i changed the seals & replaced fork oil. Will changing the bushes & springs to suit my weight help much, can do it myself or does anyone have any good contacts?

    3. Tyres, have done 5 track days with Pirelli Sport Demons, however they will literally start to smoke after 3-4 laps at EC. Where & what tires will be more suitable for this bike under track conditions?

    4. Can you get rear sets for this bike & where? Easy to scrape boots / pegs on this bike at turn 2 EC.

    let me know if there is anything else i should know, btw not looking to spend a fortune as i'll track this bike for 6-12 months until i get a new road bike & then the gixxer with be 'retired'

    cheers in advance!
  2. Drew and one other mechanic from Close motorcycles both race old VFR/RVF400s. Not sure how different they would be from your CBR (obviously inline and V4) but assuming they are from around the same period and carbied hondas might be worth calling close and asking to speak to one of them see if they can help/advise you on the tune.
  3. I got my mrs a set of Tyga rearsets last Xmas for her mc22. They are quite good. It's still possible to scrape boot but its not hindering the lean angle like the stock ones. They work with GP shift aswell.

    The forks is a very interesting topic. No one seems to make springs and valving for them. The old trick was to put a 20c coin in each fork as a preload spacer. My mate is doing a 250 budget track bike aswell. He rebuilt his forks and added 40 or 60c in each side and ran thicker fork oil. I haven't ridden it but bouncing it, it feels like its all spring with virtually no dampening, I think he overdid the preload. I've seen guys selling aftermarket fork caps with adjustable preload on eBay, they might be the way to go. Really they need to be sprung and valved properly.

    On the mrs bike she's running Dunlop GPR12A's and they have proven to be good on the track, I took it round Wakefield last week and the tyres felt good.
  4. I'm just about to put a clutch kit in my mrs bike but I reckon if you don't do that atleast try and get some heavier duty clutch springs since these bikes have a tendency to slip slightly on hard shifts. Ill see how the oem ones go, she won't be able to hack stiffer clutch springs but if it was mine I'd be beefing them up.

    Also these things could really use a quick turn throttle, theses no way you need that much progression on the track on one of these
  5. thanks for the tips,

    actually already done the 20cent piece trick, 2x per fork plus 15w oil.

    actually the front forks aren't too be bad even for the road (except potholes), so that should be ok for the track.

    use to get a wiggle under power at EC, upped the preload slightly it was quite stable.

    Dunlop GPR12A's are virtually the only sticky tyres for this bike that I can find.

    upgraded the bike with EBC springs the other week, the clutch plates were well within tolerance so didn't bother swapping those. Superheavy clutch now!

    the main issue for me is the tuning & the tyres. its running rough below 10k & flat spot at 3.5k not that it matters, have to keep it between 14-18k at EC!

    how these things don't blow after constant thrashing at the track is beyond me!
  6. With the tuning issues, Have you tried putting the standard pipe on it? My gf's bike seems to perform the same with the stock and aftermarket shorty pipe.

    It could be something like the emulsion tubes are gone on the carbs, my old cbr900 had a flat spot and turned out that was the problem.

    It might be worth taking it to someone like RC tuning, my mates taken a few carbed bikes to them, they're very helpful. Get them to run it on the dyno and see what they think the prob is.