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Thread: How do you make an XR200R sound good?

  1. #31
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    ARJ127 - God I could watch your avatar for hours. Hmmmmmmmmmmmm

    Anyway - I have nothing decent to add so - catch ya

  2. #32
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    Well I paid $750 for the bike, but that included a helmut, the manual, 2 pairs of boots and a Fox skivvy. So anything more than $200 for a new can wouldn't add up in the scheme of things, specially when I know of someone who scored a mint supertrapp for $30! - speaking of supertrapps I'm wondering if the idea is similar to 'pulse width modulation' (PWM) in that the can gives out max dB but in quick doses. You adjust the volume by changing the frequency/duration of the max dB output. In this way you get a huge pulse of subsonic sound each time the plates open. dunno just a random thought.

  3. #33
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    now i have no idea how a supertrapp works, but:

    aren't deciBells a measure of amplitude?

    as i'm sure you know, PWM just achieves an easily controlled average power output while using only one voltage/amplitude.

    so a sound tester would measure the same amplitude, and i suspect it would just sound deeper at same volume. unfortunately, stopping the noise from the motor for PWM would require you to stop the motor/sound source

    a more likely method of quietening (or loudening) a bike would be tuning the pipe for destructive (or constructive) interference of the sound waves

    most stock mufflers use baffles to smooth out the peaks/valleys thus giving a lower (and therefore legal) dB rating. most aftermarkets just use fibreglass to absorb the sound energy to acheive the end effect without as much backpressure and thus higer flow, which the market demands.

    so think of the muffler as an inductor/capacitor to smooth out the loud pulses from the motor, with a resistor to absorb the sound energy... or something like that...

    correction welcome

  4. #34
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    here's what supertrapp has to say on the matter:
    Quote Originally Posted by http://www.supertrapp.com/technology/index.asp
    Removing discs decreases the exhaust opening and increases backpressure. This effectively decreases the powerband to create more low-end torque. It also decreases exhaust tone and enriches carburetion.

    Adding discs increases the exhaust outlet and decreases back pressure. This widens the powerband at the top end. It also increases exhaust tone and leans out carburetion.
    which is basically what i've said in earlier posts

    and it's exactly how my tunable muffler worked, albeit by a different mechanism... which basically means even a spotty teenager could've come up with this "patented technology"


    imo, moving parts in a muffler are a very bad idea, which would rule out your pwm idea unless they stuck a spring steel reed in there for some reason

  5. #35
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    and on further thought:

    PWM of sound would just acheive a change in the timbre (quality) of the sound

    same amplitude(volume) and same frequency(pitch), just "sounds" different

  6. #36
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    6th October 2008 - 13:36
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    I had Custom Chambers make one for my XR250 years ago. An awesome muffler and a fair price to i thought.
    I followed up ARJ127's suggestion. Custom Chambers over East Tamaki way will do a black can for $180 (usually same day) and add an extra $30 (and 4 days) if in silver. Not bad really, but would be a hassle to leave the bike over there on a working day tho'.

  7. #37
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    @motorbyclist
    wow amazing where a random thought may lead!
    Yeah I follow you, your R/C filter analogy for a muffler sounds sane enuff!
    For a sec there I half expected yah to allude to interference waves and phase shifting like what Mazda looked at in their electronic noise cancelling mufflers. I think they got it to the stage where you could dial up your own sound wave?

    Anyway, do you reckon you can resurrect that curved pipe leading into the muffler?

  8. #38
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    Quote Originally Posted by oldskool View Post
    Anyway, do you reckon you can resurrect that curved pipe leading into the muffler?
    seriously i doubt my welding is up to the task, but i'm sure there's people who could.

    if i were you i'd go get some steel pipe of correct diamter and excessive length, figure out what bends you want, trace it out, and take it to a car muffler shop and pay a few bucks to have them do it on a hydraulic press for you.
    which is basically what i did for the pipe in my square muffler.

    then perhaps cut the pipe so it can slip over the conical part of my muffler and i'd be a fair bit more confident stick welding that on. more weld to hold it against fatigue and less likely to just burn away the end of the pipe trying to weld it


    or buy one. that usually works.

  9. #39
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    Yeah like I originally figured, good intentions but in reality too much effort for my precious spare time. It's all do-able and we know it, but the time saved for a few hundy spent on a guy who does it for a living is well worth the expense. (as long as I earn more than he does )
    The question remains on trusting a guy to come up with a sound I will like. Seems to me this part is a lucky dip on what is prob a standard can he will pull from the shelf. I guess I could go with the flock and get what the market dictates...not.
    Still, that ARROW on an XR200 I heard on youtube sounded pretty good.

  10. #40
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    Quote Originally Posted by oldskool View Post
    Yeah like I originally figured, good intentions but in reality too much effort for my precious spare time. It's all do-able and we know it, but the time saved for a few hundy spent on a guy who does it for a living is well worth the expense.
    yeah pretty much

    it makes a fun project, but once you account for time taken it's often cheaper to get the pros to do it

    although, if you DIY there's only one person to blame if it doesn't work

  11. #41
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    LOL, being a proud and patriotic Kiwi, DIY is my middle name! Mind you when it comes to something like my DIY motion simulation platform, theres not a lot of pro's in NZ that could tackle the project and if there were I'd be looking at costs well into the mid 5 figures. So sometimes DIY is the only option!

  12. #42
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    Quote Originally Posted by oldskool View Post
    How do you make an XR200R sound good?
    cover it with canaries and then set it on fire

  13. #43
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    Go to your local muffler shop and pick up a coby for about 30 bucks. They sound bloody good on bikes.

  14. #44
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    Quote Originally Posted by oldskool View Post
    I followed up ARJ127's suggestion. Custom Chambers over East Tamaki way will do a black can for $180 (usually same day) and add an extra $30 (and 4 days) if in silver. Not bad really, but would be a hassle to leave the bike over there on a working day tho'.
    I gaurantee you will be more than happy with the result from custom chambers. Otherwise, how about a standard muffler of a late model 250f, should be tons of them around since most mx guys put aftermarket mufflers on instead.
    I kept the standard mufflers on all my yzf's as i was more than happy with the awesome sound they gave.
    Go Coops

  15. #45
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    Quote Originally Posted by arj127 View Post
    I kept the standard mufflers on all my yzf's as i was more than happy with the awesome sound they gave.
    yeah well those are the straight thru fibreglass packing sort - which sound friggen sweet

    the XR has baffles in a big box and sounds like a lawn mower but quieter

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