Topic: CB400f - replacing stock muffler with slip on supertrapp

[lohebohi]

One of our CB400f bikes has a thoroughly rusted exhaust pipe.  The header is okay but there are too many holes in the muffler.  It has a nice growl with all of those exhaust holes but it is probably loosing a little power.

Does anyone have any pictures of different aftermarket mufflers mounted on a CB400f that you are willing to share along with purchase price range/vendor and fitment specs?

I am considering the Supertrapp muffler.  Does anyone know the diameter of the stock CB400f header at the collector?  IE. what size (I.D.) should I be looking for in an aftermarket slip on pipe?

I am also open to other options if anyone wants to throw out some ideas.  I have seen exhaust on CB400fs in the past that were turned upwards after the collector.  I think those look awesome but I am a little worried about condensation collecting in the pipe and leading to rust.

[Gordon]

http://crc2onlinecatalog.com/Index_Main_Frame.htm has an EMGO replacement muffler that looks pretty close to a stock 400 piece.  You'd have to check the measurements, though. 

[Vagelis]

I have a SUPERTRAPP universal muffler on my CB400F. I have it on the bike now for roughly 12 years. Never had a problem, except changing the insulation once a year. It will take you a while to fine tune it (adding or subtracting discs) but at the end it will be worth the effort.
I have a 2.5 inch intake on mine using the factory cllecter & pipes. I cut out the exit pipe on the collecter and weldded on a 2.5 inch pipe bent very slightly upwards. I think the factory collecter is a 1.3 inch. But I have a big bore piston kit, velocity stacks on the carbs & 98 main jets. After about 2 months of messing around with the discs, jets and doing plug chops, I ended up with 16 discs. It's a little on the loud side but it moves in all rpm's.
If your motor is 100% original a good starting point is 10 discs.
If you go this way and you need any help feel free to email me.

[lohebohi]

Vagelis I really like the way that Supertrapp looks on your bike.  I definately want to go with the Supertrapp

So when I pull off the stock muffler I will have a 1.3 inch pipe.  That is 33.02 mm. 

Am I going to have a problem finding a piece of pipe that will fit tight on a 33mm pipe, or is that why you did the cutting and welding?  Is there a portion of the exit pipe that is not 1.3 inches (33mm) that you used?  I am assuming I will have an easier time finding a Supertrapp with a 2.5 inch inlet as apposed to a 1.3 inch inlet.

Do you have any close ups of your connection points and the bracketry required to mount the pipe to the frame?

I spoke to someone at Supertrapp and they said I could pretty much choose from any muffler listed under their universal section.  I had wondered if I should try to get something 'close' to my application (400cc, 37hp) as a good starting point.  But she said that any of the pipes will be adjustable to work in my application.
http://www.supertrapp.com/product_sections/universal/index.asp

All these use 4 inch discs;
Megaphone. 18 inches long
Aluminum Racing Series. 12 inches long
SC Elite. 10 inch, 17 inch, or 24 inch long

[Vagelis]

Goodmorning Jeff, I'm not shure about the od on the exit pipe (1.3 inch). Just take your muffler off and measure the pipe with a ruler. I remeber that when I was looking into which muffler I should use, Supertrapp had one with the factory od. Don't go with the 2.5 inch if your motor is stock, you will not gain anything, just alot of work to cut & weld.
As for the brackets, I used the bracket that the muffler came with witch I mounted on the rear foot peg (carefull my rear footpegs are not on the rear swing arm). If you have a muffler shop close to you, try to get into good terms with the owner, and have him fabricate a peice of 12 inch long pipe with the od you need with a little upward bent about the middle of the length. Try to use a piece of stainless steel pipe that resists rust. It's a little on the heavy side but it's worth it since it doesn't rust.
As for the pictures you asked for it's kind of hard for me to upload things, I don't have a pc at home all this is done at work. You understand.
Keep me posted, by the way where are you? I'm in Athens, Greece.

[lohebohi]

I was able to measure the outside diameter of the single pipe at the rear of the 4 into 1 header.  It measured just under 1.75 inches.  A slip on with an inner diameter of 1.75 inches should be the proper size.  You should not have to press it on hard (if you have to press it in at all). 

The stock muffler is approximately 26-inches long.

Does anyone know the proper size of the exhaust manifold studs?  I Need to replace one because the nut came loos and the stud became bent.  Service Honda no longer has the exhaust studs or nuts;

90044-377-720, BOLT, STUD (6X37)
94001-06000-0S, NUT, HEX. (6MM)

Does ARP make a stud in this size?

[jotor]

Hey Jeff, you picked a nice bike to work on.

Here's a link to my gallery with a Dunstall on my 400F.  Smaller than stock muff but same shape.

http://www.sohc4.us/forums/index.php?topic=2254.0

Joe

<edit>  6 x 37 stud indicates it's 6mm dia. and 37 mm long

[nortons]

Gasket for end of 400f header collector is app 50mm=roughly 2 inches, outside diameter. I am having trouble finding muffler with inlet that large. Any ideas, suggestions?