Topic: CM400 Exhaust

[Pinhead]

I let my friend drive my CM400 last night and without warning he decided to take the damn thing off-road.   He obviously wasn't paying attention to where he was going and ran over a huge freekin' rock. The only damage I can see, luckily, is a big-ass dent and hole in the "crossover" chamber for the exhaust. I removed the chamber and looked more closely, and all of the "innards" are broke/dent/clinking around.

I also noticed that the bike sounds a whole lot better without the thing; sounds like a twin should sound. With straight pipes it's entirely too loud, though, so I'm thinking of installing 24-inch long glasspacks right on the end of the headers. Straight pipes don't seem to run nearly as well as with the crossover, though I haven't changed jets in the carbs.

I know I could buy a crossover chamber on eBay but would really like to keep the sound of singles (though toned down quite a bit). I've seen pics of CB/CM's with true dual exhausts and I know my CB360 didn't have that chamber.

The stock CM400 seems somewhat anemic already so I don't want to do anything to hurt the power. My question is, will the singles + glasspack run as well as with the crossover? From looking at the inside of the crossover chamber, it seems that it would be mighty restrictive... Perhaps an H-pipe instead of the chamber? How would I determine where to put the H-pipe in relation to the header length?

[Pinhead]

I was reading through a Clymer manual today and noticed that the Rebel 450 has the exact exhaust that I'm considering building. Simple dual pipes with an H-pipe between them.

[Alan F.]

That's a good find, I wonder what the jetting differences are between that 450 and a 400?
-Alan

[Pinhead]

That's a good question. The Clymer manual doesn't say...

[Alan F.]

BrB, I'm off to servicehonda to find the jetting differences....

I'm not sure I get the difference in slow jets, different types of carbs maybe?
But the 112 mains are common between the two though, that's something in favor of using those pipes,  I wonder if the pipes will fit a 400?...brb

Hard to tell as the clamps and collars are different between the two bikes, but they do both use the same exhaust gaskets at the cylinder head.
So it looks like those pipes will mount up to a 400.
-Alan

[Pinhead]

Niece! Good to know. Now just to score a good (cheap) set on eBay...