Difference between 4in2 and 4in1 exhausts?

[noobie]

Can anyone tell me what the difference is?

I've taken my 1k completely apart and the original exhausts are awful, the lower side completely rusted through, holes in the metal, etc...

Since de-chroming, repairing and re-chroming the old ones would be too expensive I'm looking for new exhausts, but can't seem to find any new 4in2 exhausts in Europe, only 4in1.

I've noticed many members on this board replacing the original exhausts with 4-in-1 and am curious as to why? Better sound?

Visually I like the originals much better, better thickness and length of the pipes compared to the short and slim 4-in-1; and the symmetry of pipes on both sides of the bikes is nice too; but I can't afford to give 800 EURO for originals when I can get 4-in-1 for 350 EURO.

Your help would be much appreciated.

noobie

PS: is anyone interested in my restoration project - should I start a new thread about it and keep you up to date, with pics and everything?

[Nessism]

4 into 1 is the only real choice it seems these days, in the US anyway. There is a company named Jama over in your part of the world that makes/sells more OE type pipes although they are pretty expensive from what I've seen.

Edit: seems the Jama doesn't make a 4:2 for the 1000, but they do for the 850. Sorry. http://www.laserexhausts.com/dotcont...2009_GS850.pdf

4:1 provides some tuning benifits in the high rpm range, at the expence of low speed power. Aftermarket exhaust are almost always louder than stock though so the increased flow may offset this even at low rpm.

Regarding your project, yes, we like photos. Post them up.

[trippivot]

4-1 uses sound waves to assist in an event called scavenging. This event is where the sound waves assist in the exhaust gases to be removed from the engine better.

4-2-1 is a different exhaust tuned length that gives midrange a little more boost at a small expense of top end power.

2-1 X 2 this is the pipes that go equally down each side of the bike. more bottom end torque, Quieter, only a matter of preference on the style you like to see on your bike. there are mfg. in America to get which you want

[noobie]

Thanks for your help and answers, guys!

I opened up a new thread, titled "78 GS1000E restoration project", here:
http://www.thegsresources.com/_forum...181#post915181

[Mark M]

4:1 provides some tuning benifits in the high rpm range, at the expence of low speed power.

This is not true. A 4-1 will always provide the most peak torque compared to the 4-2-1 or 2 x 2-1 setup. This is because it works better at scavenging and harnessing the pulses. It does NOT have to be at high rpm, though. It can be tuned for any rpm range you like, depending on the length and diameter of the primary tubes, collector and tailpipe. Also, a 4-2-1 will usually offer a smoother torque curve over the 4-1, at the expense of a bit of peak torque. A 4-1 will also usually have a hole in the torque curve at about 1/2 the tuning rpm. This can be minimized with careful design, but it is always something that must be dealt with.

Note that exhaust type has no effect on the tuning rpm range, they can all be designed to work at whatever rpm range you like.

That said, aftermarket pipes are usually tuned for higher rpm than the stock pipes, because people like to feel that high rpm rush. A 4-1 is also typically much lighter than the OEM exhaust system. It may save 15-20lbs. depending on which model you have.

Mark