gs400 exhaust recommendations

[78gs400cafe]

I know this isnt the exhaust forum but i wanted it directed more towards the twins. I recently purchased a 78 gs400x that the PO started to cafe. Unfortunately he hacked off the mufflers so the bike is just running the headers. I want to fix this asap as i dont want to cause any damage to the motor. My question is what exhaust would be a good choice? Ive looked into the MAC 2into1 but not certain i want to deal with re-jetting if it is required? Ive found a set of stock pipes but most are in poor shape. Anyone have any recommendations? Im a NOOB so any help will be greatly appreciated! thanks

[Mekanix]

Use a stock set of headers and buy some cheap slippons. No jetting change required.


In this link you can see a few options.

http://www.jcwhitney.com/jcwhitney/textsearch_result.jcw?shopid=100003&Nao=20&Ntt=muffler&Ntk=GLOBAL_SEARCH&D=muffler&Ntx=mode+matchallpartial&Dx=mode+matchallpartial

These specifficaly do not require jetting change.

http://www.jcwhitney.com/helix-racing-universal-megaphone-muffler/p2027495.jcwx?filterid=j3

Shop around, because you can get the same slippons for around $48.


and the result is:



good luck

[78gs400cafe]

Thank you very much!! How do you like the sounds?

[Mekanix]

love it, Its not too loud but has a nice tone at around 4400

of course down low it sounds like a chopper and up high like a rocket


Take a look at your spark plugs when you first start driving it and do a few plug chops at different RPM's and it will tell you if its safe to ride or if it will need some adjustment. Never know what else the PO might have changed.

[pete]

Sounds like a good solution to me

The other alternative I've heard is that OEM style Harley mufflers are a dime a dozen, but I'm not sure what effect they will have on jetting...

[Mekanix]

This is my third set of these pipes on two gs 400's and the ones i'm sticking with.

they're cheap enough that once the chrome rusts its worth just buying a new pair


Harley pipes depending on the if the baffles are intact could work. Although the gutted ones do not have enough back pressure.

But hey no mufflers at all sounds mean had to try it :P no driving though, just a start to hear it roar before the new pipes.



One more important thing!

if you cut the header short you will have nice low end power but feel like its got no top end.

If you have long headers and then the slipons as far back as possible then its got top end speed but low end isn't as strong as if the pipe was closser.



MY solution was a mid point.


Have the back of the exhaust be inline with the rear axle bolt

Make sure that when you cut the headers that they are the exact same lenght.

And when you put the pipes on that they are the same lenght on both sides.

The axle bolt is a good reference.

moving the exhaust in 2 inches before the bolt gave more smoothness and willingness to the bottom end and felt like i had to force the top end by giving it more gas.

Moving them 2 inches after the bolt made the top end rev in easyer but I had to give it more gas to get past the bottom end and then the top end seemed to want to rev


At the bolt its a compromise


Also, Aluminum tape is not a good sealer between pipes !!! (one reason I got rid of the first set) Glue makes a mess.




There is one more alternative that i realy liked and didn't realise as they were a new product this year is a set that have removable baffles so you can adjust it to your liking... Its on the ROAD KROME site under exhausts. Its a megaphone style pipe with 5 or six holes in the back and a few allen screws around the outside.