Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Open, straight thru exhaust...

Discussion in 'Bling and Appearance' at netrider.net.au started by nice2Bnaked, Jun 28, 2007.

  1. looking at the possibility of a straight thru exhaust system for the spada 'fighter... I have made one system without the cat-converter (collection box/chamber) and also have the original with the cat box.
    I am looking at cutting the pipe off, with no muffler.

    I have done this in the past, and it sounds great, as well as lookin nice and tidy.
    Before you guys start with the legalities and RW stuff, I know that its not the done thing, blah blah blah, but just want to know if it is bad for the motor, as exhaust gasses are not processed in the same matter.

    Power is not an issue, as I will have one demerit point until 2011 so the less the power the better. I am also opening up the other end with individual pod filters, or modified airbox, making her breathe a bit easier.

    The bike will be doing all sorts of riding, from freeway to stop/start.

    Hope someone, somewhere, sometime, will honour me with the wisdom that shalt quash this enquiry...
  2. Just remember to buy some ear plugs. Is there anyway you can put the muffler back on if you can't stand the really loud noise on long rides? People will at least know your coming whether that be a good thing or a bad thing.
  3. Just get one of those "when I grow up I wanna be a Harley" stickers and everything should be OK. :wink:

    Sorry, can't help with any actual facts.
  4. With no restriction on the exhaust at all, you may go dangerously lean on teh fuel.
    I'd go to a speed shop and get a $40 glasspack muffler, they sound sick and kill a little noise, but flow almost as well as an open pipe.
    Paint it stove black for a Kustom look.

    Regards, Andrew.
  5. Yeah. When designing mufflers for our Formula SAE car, I measured our CBR600F4i motor at 126dB without a muffler, half a metre away.

    To put that in perspective, WorkCover says you can be 'safely' exposed to 85dB for 8 hours a day and only have about a 10dB hearing loss by the time you retire. At 120dB you'll get your "safe daily dosage" of noise in just, uh... seven seconds. :)

    A glasspack muffler might be worth considering. And earplugs.

    Mechanically, the engine won't be harmed by having "zoomies" on the exhaust side with no muffler at all. Carburettors will have to be retuned and rejetted.
  6. sometimes you can get air back up pipes which is not good for exhaust valves. The sound will be annoying too. Listen for bubble and popping on trailing throttle.

    +2 for the rejet.
  7. 126db is like sitting on top of a jet engine during a fully loaded 747 launch.

    I dunno about you but that isnt my idea of a good time.

    You need some sort of baffling. Even my "rather fruity" exhausts have at least some sembalance of baffling.

    I remember running my little 250 with no exhaust once... for about 1 lap of the block. Not good for motor, not good for neighbors, not good for wallet.
  8. ...so yes, getting back on track... I know that it is loud, as I have heard it when I was running no pipe (the pipe actually broke off in a fall, and i was too poor to replace for weeks)
    I did wear plugs, and will do again. The reason why i want a shorty pipe coming out near the back of my foot is becouse I have no hanger for it... My bike ends at the back of the riders seat, so half a subframe, no pillion pegs ect... Just like a chopped down beull.

    So, even if I have the carbs rejetted, this WILL DEFINATELY damage my engine?
  9. MAY. It depends on pipe size and pressure etc.
  10. I might be selling mine.
    Mines a straight though and it's loud.
    It is for a ZXR250C with three bolts.
    It's a pain in the ass when I warm the bike up knowing there are people who get pissed off.
    The reason I might be selling, also, is because got pulled over and done for excessive noise. So might put stock on for a bit but if I can't be stuffed replacing it, I'll sell it.
  11. no reason why you wouldnt be able to run a straight through system and run a constricted pipe further down the exhaust. Just need to make sure it is properly designed - try speaking/working with an exhaust specialist.
    Air drawback = combustion in the pipes, pity there is no afterburner effect. :demon: