Topic: 400f exhaust question

[weschaffnit]

im have a 1977 cb400f that im running with no muffler at the moment. i took the stock muffler off a few days ago to clean it up a bit and started up the bike without it. the bike seems to run alot better without it on and sounds really good. the rpms seem to climb faster and the bike seems to have more power.  i was thinking the muffler may have had alot of carbon build up and was to restricting the engine. anyway i was thinking of getting a small can exhaust muffler to slap on the end of the headers thats not to restrictive and will cut the noise down slightly. does anyone have any (cheap) suggestions on which muffler to look for? also the headers are pretty bad with alot of patches in them. i have heard that gs550 aftermarket 4-to-1 exhaust headers will fit on a 400f. i say this because my friend just bought a set for his 81 gs550 and is not going to use them. your input is appreciated.

[Triffecpa]

The 400F muffler is prone to rusting out badly from the inside.  It could be that yours is partially clogged.  Any small muffler (check that the ID on the new muffler matches the size of the pipe on the end of the header) shouold work OK.  You might have to rejet the carbs if you run a less restrictive muffler.  In fact, that may be why the bike seems to run better with the muffler off.  Is the jetting in the carbs stock now, or are the main jets bigger?  Stock is 75 mains if I remember correctly.

Don't have any idea if the GS550 header will fit.  The header pipes on the 400F come straight out of the head, as opposed to the 750 that comes out at different angles.  So if the distance between the header pipes matches up, you might get lucky. 

Let the rest of us 400F owners know if the GS pipes fit.

Tracy

[weschaffnit]

i bought the bike from an old guy i know up the street from me. he was about 60 when he bought the bike in 77 so im pretty sure that he didnt do any upgrades to the carbs. it seems bone stock. im just kinda lost about which exhuast to look for. something really simple like a super trapp but i know theres more out there. and ill see if the headers match up

[zanthose]

i don't know if this would work but I've always wondered if you could use a car/truck glass pack from an auto parts store they run like $20 any thoughts