After-market mufflers question

[JimO]

im looking at a set of predator mufflers off a xjr 1300 and am thinking of having them fitted to my Raptor 1000 (will be keeping the factory cans for wof time) apart from the obvious farkin about to get them to fit would there be a down side?? do V Twins need a different muffler to a 4 cilinder....cheers jim

[slimjim]

wouldn't think so....might be different fitting a 250 set of mufflers to a 1300...but going down in motor output size can't see a problem...also if the xjr mufflers are standard...trick to drill off three rivets on end plate...pull out end plate has long down pipe fitted to plate...can cut this pipe short and add set ot holes to pipe...will add nicer note to exhaust sound..

[JimO]

cheers for that but he wants $1050 for them so i feel thats to expensive for a couple of 2nd hand mufflers that he says cost him $1200 new...i reckon $600

[James Deuce]

Yes there is a difference. V-Twin cans are bigger for a reason. Volumetric efficiencies are different between a 4 and twin of similar capacity simply because the bore on the twin is bigger, and each can has to handle 500cc worth of expelled gas for the twin as opposed to 250cc per ignition for the four.

[slimjim]

Yes there is a difference. V-Twin cans are bigger for a reason. Volumetric efficiencies are different between a 4 and twin of similar capacity simply because the bore on the twin is bigger, and each can has to handle 500cc worth of expelled gas for the twin as opposed to 250cc per ignition for the four.

..bigger...yea right...fuck a four is firing twice as fast as a twin...haha..and muffler size of a 1300

[James Deuce]

..bigger...yea right...fuck a four is firing twice as fast as a twin...haha..and muffler size of a 1300

No, stop and think about it. It's not firing twice as fast either, it's firing once every four strokes the same as the V-Twin. Rpm isn't particularly relevant in this discussion, capacity is.

If you put a pipe on it designed for a 4 which fires one cylinder at a time, one cylinder which is half the size (roughly) of a V-Twin cylinder you won't be providing enough volume for the V-twin to be expelling its larger volume of exhaust gas per cylinder.

1300 divided by 4 is still only 325cc, 175cc short of the 500cc each V-twin cylinder will be spitting out every time it fires.

For example each of the twin mufflers on a TRX 850 is much bigger than each one of the two mufflers on the XJR. The TRX is spitting out 100cc more worth exhaust effluvium. As I said there's a reason (other than stupid Euro 3 & 4 compliance) why V-Twin mufflers are bigger than mufflers for a 4 or 6 of the same capacity. They have to contain more gas (and therefore more noise) for each bang part of the suck, compress, bang, blow cycle. Gas flow is really important. Get it wrong and you simply lose power.

[slimjim]

o so you say....when you have four going into one muffler then that muffler is designed for a 2600cc exhaust 1300x 2=2600... humm and for them been bigger...no in longer in length due to the slowness a twin pushes out its volume..and then gets balanced via balance tube,

[James Deuce]

o so you say....when you have four going into one muffler then that muffler is designed for a 2600cc exhaust 1300x 2=2600... humm and for them been bigger...no in longer in length due to the slowness a twin pushes out its volume..and then gets balanced via balance tube,

You're making no sense at all.

[hospitalfood]

different pipes ( and different air filters ) will affect airflow, therefore they usually affect the fuel/air mix.
modern fuel injected bikes can often reset the fuel/air mix ( not always as much as it needs to be ! ), older bikes with carbs dont.
putting pipes ( or performance air filters ) on that increase air flow usually cause the bike to run lean.
lean is mean but not for long ! because the engine runs hotter, lean running can cause serious problems.

there are others on this site who can tell you more about it.

[pritch]

Bike mags have done tests on after-market cans and found that some brands actually produce less horsepower than the standard muffler. And that was starting out with the can recommended for the particular model.

Fitting any old can to a bike can probably be done, but why would you?

[Motoxparts]

Two Brothers at www.motoxparts.co.nz