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On a tweaking note

Discussion in 'General Motorcycling Discussion' started by nil_orally, Oct 31, 2004.

  1. Howdy folks.

    For reasons of dharma, I currently have on the bench the engine out of my 2001 Suzuki GZ250. Some idiot ran it out of oil (to be honest, it hasn't used a skerrick in the last six months, then ate a litre in 2 weeeks - no visible leaks or evidence in the exhaust. I suspect there is more to this than mere tardiness).

    I have approached several wreckers in the outer East Melbourne suburbs about a replacement, but they all stare blankly, then shake their head slowly.

    Ok, the hard sell bit. If I am going to be forced to rebuild this sucker, does anyone know what can be done to get more speed / power at the the top end? (No "put a Honda in it", please). The bike always had (just) enough acceleration from the lights for me at this stage of my riding learning curve, but it struggles to get from 90kph to 100kph. On a flat surface and no wind, it takes 25 seconds to get from 100kph to 110kph. On a slight incline, the top speed is curtailed significantly, generally requiring a kickdown. Ok, ok, at 6'1" and 100kg I make a good parachute for the poor beast, but short of drilling holes in myself to reduce mass and surface area, I am stuck with this.

    I would hate to have to catch a train to the coffee nights.

  2. This is a tough challenge :shock:

    You are obviously never going to get much out of that engine which looks suspiciously like a bored out GS125 lump. First thing would be to get in serviced and check the engine timing, values, air filter & give it a compression test. This will give you max performance stock.

    Next up would be to de-restrict the stock exhaust (do a Net search), then fit a bigger carb from a compatible Suzuki (you'll have to do some homework on this) and a racing air-filter (ditch the standard airbox) and tune to suit (not an easy job, need to change the jets and adjust the air-screw etc).

    This should give you the max power possible for that engine without getting really silly....
  3. GSXR1000 engine?
    Should be heaps available at the wreckers, and you should get the top end you want....
  4. ok , i have some good news for you

    the gz250 murauder is the same motor as the GN250 .
    the GN250 has less crome and is more easily abtainable through wreckers .

    bad news
    Approx $850 change over , you give them the old one they give you tha working one .

    hope thats helps .
  5. Thanks for the info folks.

    There seems to be a dearth of GN250 motors at the moment in the 7 wreckers I have tried, so I will have to put my name down and keep trying (everyone had one "just last week").

    It will give me time to research more on performance improvements too, I guess. And to plan my next assult on Tassie, where this all started (on the last day, thankfully). For those who haven't been there - go. It's like riding the Black Spur for 4 hours, having lunch, then doing it again, with bugger all traffic. (They have a nasty habit of putting right-handers just after the crest of a hill and forgetting to sign it, though. It quite a few places, the signs advising 45kph corners would have been handy 2 corners earlier. Ride within your limits. I found mine).

    btw, everything above the gearbox is scrap value only. One of the valve heads let go. *Sigh*.

    On the ride for justice, will you take a rather heavy pushbike in the group. Used to be a motorbike......