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ZZR250 Questions - Cans and Fairings repair

Discussion in 'Bling and Appearance' at netrider.net.au started by robbie3786, Apr 7, 2008.

  1. Ok, basically, i had a fall like 8 months ago, scratched up my RH FS fairing, and kinda cracked it a little. Also dented my exhaust with my foot.

    So i have two questions:

    1) How wuold i go about repairing the fairing my self? Would Supa glue siffice to fix the crack, followed by some light sanding and a re-paint? Or would it pay to have this all done professionally? I am keen to do it myself though, it works out better economically

    2) With the exhaust, i've been considering purchasing a new exhaust system (2-1) mainly to enhance the look and sound of the bike not really after increasing performance but understandibly better airflow = slight increase in performance. Also, what is re-jetting? like... i mean i haven o idea what it is as i am a complete Noob (newbie) any help? but i did manage to figure out that it has somethign to do with the carbies, and that if i get a new exhaust system, the carbies need to re-tuned or re-jetted..

    Any advice would be greatly appreciated.

    OHH One more question - What is your preference for chain lube; Silicon spray? or Drip oil? I've only ever used silicon spray stuff.

  2. As far as question 1 goes CA adhesives (superglue) is generally no good simply because it is far too brittle and will simply snap again if the fairing flexes (and just the force of the wind when riding can be enough for this).
    What you want is to plastic weld - this can either be done chemically (dangerous if you don't know what you're doing) or thermally by simply melting some scrap plastic or cable tyres and using that as a "glue" and filler.
    Sanding and painting can be done yourself fairly cheaply and easily, hard part is matching the paint (though depends on what colour it is).

    Rejetting is simply changing the size of the tube that sucks the petrol into the carbs. Changing the exhaust and/or airbox can mean more air - which means you need more petrol or you'll run lean which can burn a hole in the piston (petrol helps keep the engine cool and inhibits oxidation). Too much fuel though and it'll foul the plugs and the engine won't start or run easily.
  3. Better airflow without rejetting = slight decrease in performance actually. At least in carb bikes (don't adjust for changes).
  4. ok well i changed my Airfilter about 2 months ago (bought a K&N Filter off ebay) so how do i re-jet? Is this somethign that should be handled by a bike shop? or does it just take some Will pwoer and common sense?
  5. Changing the jets is easy. Knowing what jets to use, and any other adjustments that might need to be made to the tuning, is what requires skill if you want the bike to run the way you want. Otherwise as Phizog pointed out you may find yourself with less power than you started with (just more noise). For this you really need an exhaust gas analyzer (which most mechanics should have) or a dyno (which dyno-tune places have). Also helps if you know what you want from the engine (ie better response at low revs/more peak power/whatever).
  6. If it is just a K&N replacement for the oem filter element no rejetting is required.

    If you have removed the airbox and replaced it and the oem filter with pods you will need to rejet, because removing the airbox restriction allows a lot more air through.


    Trevor G
  7. If you use a staintune muffler then they will normally say you don't need to rejet. In practice a slight extra part of a horsepower or two might be released by going up one size on the mains (mainjets) from a 105 (I think) to maybe a 110.

    Increasing the main jet(s) also allows more fuel through from 1/4 throttle opening on. The main jet takes over fully from 3/4 throttle (approx). A "cheats" way to help the midrange is to place a small washer under the jet needle, which sits in the throttle slide. You have to choose this washer OD and ID) carefully. (Outside diameter and inside diameter)

    While exhaust gas analysis can be fun, it is not necessary - everyone used trial and error to change jets prior to analysis becoming available. In addition, analysis is also more useful for EFI systems (not on your bike) where you control the extra fuel flow needed by making slight adjustments up or down to the fuel flow delivered by the injectors.

    Carburettors are much more linear devices which do not need (and cannot provide) such minor variations in "output".

    In other words, go up one size on the mains and maybe lift the needle by 0.5mm.


    Trevor G