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VTR 250 Air filter

Discussion in 'Modifications and Projects' started by ihaveduff, Nov 10, 2007.

  1. It's come time for me to give my filter a change. Does anyone know if anyone makes an aftermarket filter for these? Would it be worthwhile putting in a better flowing one?

    *paging idontlikemondays* :p
  2. I think there would be nil gain in performance, it's a well debated topic, some believe it improves performance because the less restrictive aftermarket ones allow greater airflow, and the non-believers say that greater flow comes at the expense of less filtration.

    If you do lots of km, and would be paying for OEM's all the time, the only benefit i see is an economic one with a K&N or BMC etc.
  3. *idontlikemondays comes to the rescue* :LOL: :cool:
    james yeah look if you want to do it, do it! but this WILL require a rejet. dynojet does the kits for about 80 bucks i think for the VTR. filter, yes an after market one is made, its a BMC i think??? dont hold me to that but i do know there is one available and from memory the long time ago i made enquiries about this it was about 100 bucks. i know that K&N do not do one. for economic reasons if i had my bike again i would have done it. at 50 bucks a filter its not cheap to get the factory ones. and you "need" to replace them every 18000kms according to the factory. but in our city which is equivilant to smoking 5 fags a day, i do mine every 12 000 kms, otherwise the whole filter will be black.
    ive already told you what was involved in a rejet, if you deleted that pm give us a yell, ill run over it again for you. if you need a hand installing it give us a yell too. ive installed a dynojet kit and K&N in the storm and its still running :LOL:
    other thing you'll need to do is get a confirmatory dyno run, this will cost you 90 bucks at flywheels and will tell you if you need to make adjustments to the needles and idle circuits.
    maximum peak HP gain i rekon would be no more than a couple of ponies. you might get a boost in the midrange though. if you bike is going to be off the road for a while id check other things in the motor like the condition of the valves/seats, do a compression test. there aint no point in doing three hundred bucks in flow mods if power is leaking!
  4. You might like to read this comprehensive test:


    In summary, the difference in airflow between the best and the worst was so slight as to show no real performance gain. Even removing the filter itself produces such a slight improvement it is not worthwhile. This agrees with my seat-of-the-pants findings in cars and bikes over some years

    However changing the airbox itself, to flow more air, is what most performance shops do when they replace an element and rejet. You do not need to rejet for just a filter change if everything else is still standard or unchanged!

    The test also showed that original-style paper elements are the best all round for filtration and flow. The VTR250 original element is fine - because it covers such a large area the reduction in flow through the element itself is very small, as in the test findings. However, the inlet or airbox lid for the VTR is very restrictive to reduce noise. Opening it up in the right way should should produce noticeable performance gains with the appropriate jetting.

    One of these days (since I now have some jets) I will open up the airbox lid and try it out. BTW, a melbourne guy who races a VTR with Spada heads reckons that his attempts at opening the airbox did not show any performance gains - I did not see his efforts, but from chatting with him I think he might have gone about it the wrong way. ;-) I'll let you know one day, hopefully soon.

    Because it is such a big job to change the main jets on the VTR250 I have been putting the job off. It takes several hours!


    Trevor G

    PS Some years back air filter elements were much smaller and thus more restrictive of airflow. That is not so common now.
  5. OK guys, i opened up the airbox and figured out a big part...

    i was missing 4 screws and the airbox was half open :LOL: ... the back half of the filter was dirty, the front was clean :p ... i found 2 of them in the V of the engine and put two more in to keep it down!

    i also bit the bullet and did a rejet/lifted the needles (i went from 115's to 120's) - HUGE improvement! I finally have the grunt i used to have before pipe! *looking forward to next lot of twisties* :LOL:

    Thanks for the advice in the PM/post dom!
  6. Where did you get the jets from?and how much? Does the stock exhaust allow enough flow to handle a rejet or is a new exhaust ESSENTIAL? (Im on a budget at the moment)
  7. i got my jets for free (my boss was throwing them out of his old Honda 750), though from memory you can buy jets for around $10 each

    the washers to raise the needles are bloody small

    I'd say not to bother with a rejet with a stock exhaust
  8. Dyno dyno dyno dyno dyno :p
  9. :rofl: :rofl: :rofl:

    dyno a 250??

    after this weekends run mate!
  10. Yep, dyno the biatch or you won't know if it's getting better or worse with the changes. Placebo, who knows, but bring it on over the weekend :cool: