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Drilling Stock ZL600 Mufflers

Steve C Jun 5, 2014

  1. Steve C

    Steve C Member

    Hey guys,

    Throwing around the idea of putting a few extra holes in the tail pipes of my ZL (between 2 and 4 holes in each muffler) to add some extra sound without replacing cans, rejetting and all that good stuff. So a few things:

    Do you guys think that by adding a few holes to increase the flow some with stock airbox/filter that I can get away without rejetting?

    Has anyone done the same on their ZL600 that they can recommend drill sizes, number of holes, advice? In addition, if anyone has done this, how does it sound? Worth it or no?
  2. Jarney

    Jarney Strip Warrior Staff Member Administrator Super Moderator Supporting Member

    Last edited by a moderator: Feb 3, 2017
  3. Reptar

    Reptar Active Member

    I would not recommend it if you plan to keep stock jetting.
    Kawasaki engineers specifically designed the airbox and exhaust on our bikes, to have a certain Helmholtz resonance that aids our engines in achieving the low end character they are known for. If you alter either one without compensation, (and still get the bike to acceptably run) over time, your engine will suffer.
  4. Steve C

    Steve C Member

    Yea I suppose you're right reptar, just a thought in order to get a few more decibels our of her. On the other hand, anyone out there running a reasonably priced aftermarket pipe and with what jetting?
  5. gosupes

    gosupes Senior Member Supporting Member

    Wow reptar, heavy reading with the reference to Helmholtz, but I dont think momma Kaw put that much thought into the tone quality when designing the airbox and mufflers. I have designed fixtures around Helmholtz coils but I had to look up his theory on resonance. I just don't think those theories were the driving force behind the size of the airbox and the design of the mufflers.
  6. Reptar

    Reptar Active Member

    I was mostly referring to their effect of intake and exhaust port pressures rather than sound resonance. =P I could be wrong though.
    Last edited by a moderator: Jun 6, 2014
  7. 87kawzl

    87kawzl Well-Known Member

    You could try to pull a gasket off crossover or muffler to get a few more db without a mod to your stock parts. I think you will be pleasantly surprised when you make the change.
  8. Steve C

    Steve C Member

    " You could try to pull a gasket off crossover or muffler to get a few more db without a mod to your stock parts. I think you will be pleasantly surprised when you make the change"

    Not really sure what you are talking about :/...Can you elaborate?
  9. Steve C

    Steve C Member

    @ Reptar,

    I totally understand that a significant modification to the exhaust flow will decrease back pressure and could possibly effect the exhaust valves without the proper jetting. I just wonder if a few extra holes at the end of the muffler with all the other baffles and piping intact could affect the valves or the way the engine runs...I dunno man.
  10. Sloppyburpfest

    Sloppyburpfest Member

    Yes, I know this is an old thread...

    Just wanted to say from experience, my 1996 ZL600B came without that exhaust crossover gasket from the previous owner. When I bought it, seller told me that he had tried to make it louder, but didn't say what he did. For years it was way too loud for me. Fortunately, last year I accidentally discovered that putting the crossover gasket back on made the bike much quieter. I'm much happier with it now.

  11. R. J.

    R. J. Senior Member

    :hello: From my experience if a bike does not have properly jetted carbs with any exhaust modifications can & will result in less power especially an open exhaust system with no baffles. You need a certain amount of back pressure in order to have a finely tuned machine for maximum horse power. For example during this past Bikeweek Daytona I went to Yotech in Daytona & they was doing free Dynos. This really big & loud obnoxious Harley rider was so pissed off that when his bike was Dynoed it made 8 less horse power than when his bike was stock. What did he have on it. Vance & Hines with no baffles & a $8K S&S big boar kit. :laughing7: The Dyno guy even told him up front not to be surprised if it makes less HP than stock. He told the guy to do another run :laughing7: that came up 9 HP less. :laughing7: He told the guy that he didn't know what he was doing. The guy said I work for Team Suzuki take your hog & go. :laughing7:
  12. Drdeth

    Drdeth New Member

    LOL louder bikes go faster, and if they don't, Loud pipes save lives, Hog guys are not right in the head
    I'm not fond of loud for no reason, I would rather have quiet and fast than loud and fast
    Some guys just get off on the Faw Q of stuff that noisy

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