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Muffler technical question

Discussion in 'Technical and Troubleshooting Torque' started by adge82, Mar 7, 2006.

  1. I know with cars that changing a muffler will do little to the overall running of the car, Eg: changing to a canon type muffler will change the way your exhaust sounds but does little for performance if the rest of the system is left stock.

    On a motorbike is the same true?

    Im not looking for a performance gain at all, thats counter-productive on a 250.
    What i am looking for is a noise level gain.

    My car runs a straight pipe, no muff. Looks like its got a muff, but it doesnt, and it sounds fantastic.

    If i were to do the same on my bike, seeing that its not fuel injected, would this adversely affect the fuel system (carbies).
    Would i need to do anything if this was the only modification?

    I know very little about carb'd engines and imagine that changing something that does not necessarily change the restriction or flow of spent gas from the exhaust would do nothing to the performance of the engine.
    Am i correct?

  2. well if its not going to change the gas flow or back pressure .......... its not going to change the sound either ............. if it does well your looking at rejetting ... all depends on the system u shoose .......... slip on,s change very little BUT do change somethings .... les noticeable is all .... but all exhaust changes ... b car or bike will / should involve other re configurations ... ie air flow or jetting
  3. You may need to change the jetting alittle but thats debateable,
    some will say you must rejet the carbs, others like myself will say try it out for a few tanks and see if you notice the power is down or your useing more fuel etc etc

    personally myself and a few others have removed the baffles on our VTR1000's
    and still have yet to even rethink about rejeting, yes the noise improved and the low rpm pickup changed slightly "for the better"
    But overall power and fuel economy ( cough cough ) didn't change enough to warrant forking out the dyno $$ to get it rejeted properly.

    Done over 30k since the 'bafflectomy' and she has just been in for a major o/haul service and no signs of burnt valves etc etc, compression is right in high end of the spec's and the carbys didn't need touching........ balance/emisions where right on the money ! :cool:
  4. Yeah just about all changes you make to a carb'd bikes exhaust are going to require re-jetting or at a bare minimum re-tuning to suit the new systems.

    Sometimes this change may only be to make the bike run smoother, othertimes it may be because the bike is running lean and you will damage the engine without a re-jet etc etc.

    It's horses for course really depending on how drastic the change is from the stock exhaust!
  5. You guys may be able to help me also, I have put a yoshi slip on on my GSXR, sounds and looks great, and I am now blowing a little smoke under hard acceleration. A mate of mine has told me it is running rich and I should have my fuel system remapped. Any thoughts?
  6. It could need remapping OR its just normal black smoke on extremly hard acceleration OR your A/F could be due for a clean / replacement making your baby run alittle rich ? or its just a normal spewsuki !

    Did that help :LOL: :LOL:
  7. Of course, the old Spewsuki, that has to be it!
  8. on my 250 i didnt get it rejetted... but then again i bought the bike new and got the muffler put on before i even rode it
    im not sure if it gave any more power but it did sound awsome...
    on my new bike i just got amuffler about 3 weeks ago and i havnt touched the efi or got it remapped as its fine and hasnt missed a beat..
  9. With regard to the VTR bafflectomy, the VTRs only require a rejet once you fix the shitty airbox and replace the crappy stock filter with K&N. Otherwise it's not getting enough air in to require a rejet. So the moral of the story is if you not only want your VTR to sound good but to go good, get the air filter and HRC jet kit as well.
    Regarding the GSXR600 K4, it's EFI. It doesn't have as advanced an A/F system as an EFI car but it can still deal with minor changes in exhaust flow. And adding a Yoshi is only a very minor change. It still would benefit from a remap though. Bikes are usually setup to run rich from standard, as a safety precaution. I haven't seen a new bike that hasn't run better after a rejet/remap.
    Balls Tuning specialise in Zukis, they'll get your dog biting not just barking.
    On a ZXR250 the power gain from adding an exhaust is going to be so minimal that even a rejet won't be noticeable. Personally I wouldn't waste my money, save it for when you buy a real bike.
  10. are balls tuning in melb??
  11. cheers dude ill have to have a look
    so really u think they can get a better tune out of my bike... or make it run better then it is??
    cause man i wouldnt mind some extra ponys :grin: :grin:
  12. Horsepower gains will be minimal, couple of HP at best. But quite often bikes have a flat spot around 5000rpm, where the EPA tests them for noise. Balls can smoothen the torque curve out so it will feel like your bike has more grunt. In reality it just means a smoother and more tractable power delivery.
    Definitely worthwhile. My mate had his K4 1000 done and it was like riding a completely different bike. Wanted to wheelie constantly.