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a little torque for xt225

Discussion in 'Modifications and Projects' started by ridgey, Dec 27, 2006.

  1. Hi guys.
    Looking for ideas for my little xt225/250
    I realise it will never be a grunt machine, but looking for a little extra fun. I love the size and weight of this bike. I find it the easiest thing to jump on for short trips, and i get it on the dirt a bit. I have other, more powerful bikes, but dont want to part with the xt.
    The little baby is almost new. Only got 4000kms on the clock.
    Have "adjusted" the exhaust (using a holesaw) and adjusted the jets and airbox to match. The thing sounds awesome now, even if it is grumpy when cold. Has lost the very low down torque, due to no backpressure, but mid-range is much better.
    I now have a little oil cooler and pump to put on, and some performance valve springs (from a racing 4wheel bike shop in america), and am wondering about cam grind, and compression ect.
    Has anybody had any expreience with these motors? Any reccomendations ? Just want some torque low-mid range.
    I am going to pump oil from the sump, through the oil cooler, and back into the rocker cover, over the valve train, so hopefully it should stay nice and cool.

  2. I would up the jetting a touch maybe 2 steps main and raise the needle 1 clip for a start after the performance mods to the exhaust

    I would then give the head a work over especially the port floor area you can get 10 to 15 percent more flow through that head easy as they are a cheap bike so they dont spend much time at all ensuring all the dags and dross is removed from the ports on economy models and there is always more to be gained by removing the steps around the seats and over the port floor area the upper floor area is always pretty good and easier to get at.

    I would leave the cam alone at this stage as it sounds like you want torque not revs i would replace the springs though

    Good Luch with it
  3. Hey dude I had one of theses bikes a few years ago was awesome put 13000kms on her rode from vic border up to tweed heads and back was fun, cut the exauhst and pulled all baffles out then re welded rear back up so it still had back pressure just a little bit bigger outlet than it was and did the trick was heaps better low and mid range and did the air box to suck in more air, I reckon you biggest and most reliable gain for fun would be change the gearing depending on your riding ie.. commuting , high speeds or bush fun
  4. Thanks for the great advice guys. Brucey your advice on the head sounds like the cheapest improvement ever. Nice. Chazpowers did you use the original plate when you welded the end back on? or make a new 1 with larger hole? Sounds like the solution to my back pressure prob. Not really sure what to do with the gear ratio. I mostly use bike for local aera stuff, and not much highway work (i have a r6 for that) but the gearing already seems very low. will polish up head, then see how we go.

  5. Ahhh from memory adam used the same plate and just blew a bigger hole in it and fitted a short piece of pipe into hole to use as outlet then welded pipe to plate cleaned it up then welded plate back in sounded heaps better and let the engine open up with out baffles and restricors ...I am sure this was a legal modification lol
  6. update: Things are looking up for the little baby.
    Have aquired a fmx powercore4 muffler and kick starter for it, thank you e-bay, and found a group in america that seem to know how to tickle these engines just right.
    http://www.xr100.com/ttr230.htm#TTR230 to 250cc Ultimate Big Bore Kit
    Its for a tt-r230 but they use same 225cc motor.
    Will get the big bore and piston ect, and see somebody like wade cams in melb for the cam. will give the head a good going over while its off, may even get it done professionally, as it is fairly cheap.
    Does anybody have any experience with the 32mm Mikuni flatslide carburetor? Is this a higher performance stye than the su style that is stock?
  7. why dont you just buy a wr250 or similar might be cheaper lighter and quicker? just a thought lol but good luck with it ... by the way mine was grumpy when cold as well and it was like it from new!!
  8. Th flatslide will give a little more peak power, at the expense of low and some midrange.

    Not worth the trouble of setting it up to fuel smoothly (jets and needles) imo on a roadbike.
  9. Given the 10% capacity increase and the top end the cams should give, I think i may need the sort of carb you discribe. Im not sure the little oam carb has enough adjustment. The pre-jetted flatside and matching airbox sounds a pretty simple if expensive solution.
    Its a bit of a change of plan, started off looking for a little extra torque, end up with xr & cr-f power levels, in a much lighter bike.
    p.s. bike is a dual sport and spends as much time off rd as on. Road legal knobbie tyres ect.