Bought a Supertrapp for my GS400/425/450 MAC exhaust, here is how it went.

[midnightcafe]

not to hijack your thread, but I'm looking for a similar replacement for my MAC muffler:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=170337221771&ssPageName=STRK:MEWAX:IT#ht_500wt_1182

very cheap, but I'm gonna need to muffle it somehow I'd like a little more sound over stock, but I don't want to be annoying everyone in a 2 mile radius. motorcycle baffle and baffle insulation would keep the noise down?

[donimo]

So, here is a question:

I have a supertrapp pipe and stock jetting, how do I know how many discs to put in to get the pipe in it's "happy place" before I start carb tuning?

I started with 6, seems to run great, tried 5 just for s&g and it seems to tame it own a bit so I am pretty sure going lower isn't right. And 6 is already about as loud as I want it.

So is that ok, anybody with a supertrapp have any tuning advice?

Are 120 jets a good starting place? Stock is 117.5. I will do some official plug chops soon enough, unofficial ones look the same as before, black ring and bottom fading to a dark grey at the top of the electrode.

[srsupertrap]

I would go with six discs if that 's an acceptable noise level for your ear. Most 4 into 1 (V&H, SuperTrapp) aftermarket manufacturers recommend bumping the main jet by 3 to 4 sizes. Since you are adding a Supertrapp muffler to your stock 400 head pipes bumping the main jet by one size is probably a good starting point. You probably wll have to tweak the air screws etc to get transitions right. When you perform plug chops I would mark the the throttle grip to locate 3/4 open and make sure you reach that point before drawing any main jetting conclusions.

IMO & experience adding/removing one disc has no effect on overall jetting.

[donimo]

I would go with six discs if that 's an acceptable noise level for your ear. Most 4 into 1 (V&H, SuperTrapp) aftermarket manufacturers recommend bumping the main jet by 3 to 4 sizes. Since you are adding a Supertrapp muffler to your stock 400 head pipes bumping the main jet by one size is probably a good starting point. You probably wll have to tweak the air screws etc to get transitions right. When you perform plug chops I would mark the the throttle grip to locate 3/4 open and make sure you reach that point before drawing any main jetting conclusions.

IMO & experience adding/removing one disc has no effect on overall jetting.

It is a MAC 2-1 header, OD seems the same as stock though. But into a 2" collector/pipe.

so just to confirm, mark throttle at 3/4 and make sure to go at least that high (not WOT?) then kill the engine and pull the plug?

also I have heard conflicting info on whether "one size" is 2.5 "numbers" up or 5? Guy at the bike shiop I bought the jets from says that going from 117.5 to 120 is just "half" a size up.

I will try the 120's, see what happens and go from there, might take me a couple weeks though haha.

[donimo]

Hmm, i went back to 6 discs, it is a bit louder, and it SEEMS to go better, is this just my ears telling my butt it's going faster?

Honda Civic syndrome?

I have never heard a bike that sounds like mine, not that it sounds better than any other bike I have heard, but it's different

I read the manual that came with the can, it says that I should "tune it for stock" and then jet up later. Is it possible to tune my setup for the stock jets until I have time to mess with the carbs?

[salty_monk]

Why don't you ignore the top mount completely & get a nice bit of AL or stainless to make a strap to mount it on?
That way you only need to use the mounting bolt & all you'd see from the side is the strap going round the muffler.