XR400

ConqSoft · 01-15-2004, 8:30 AM

Ok, it says it's a single cylinder, and it looks like one, but why does it have two exhaust headers coming off of it?

DevilDog · 01-15-2004, 9:03 AM

Must we ask hard questions? Maybe to give it a beefy look?

johnnycrash · 01-15-2004, 9:11 AM

Quote:

Originally Posted by ConqSoft

Ok, it says it's a single cylinder, and it looks like one, but why does it have two exhaust headers coming off of it?

Two exhaust valves. One header tube for each.

WetShrub · 01-15-2004, 9:57 AM

Guy at work here has an old Husqvarna that is similar except it goes 2-1-2 undertail.

fl-929 · 01-15-2004, 11:45 AM

I was watching the Dakar and wondering the same thing. The announcer talked about a single cylinder going by, but then it had dual exhaust cans.

johnnycrash · 01-15-2004, 12:16 PM

Go look at any single cylinder thumper. They ALL have two headers coming from the cylinder head, but most combine into one tube that goes to one can. The CRF and YZF headers join immediately after coming out of the head. My KTM has two headers that join right before the can.

Some versions of Husqvarna's 610 had two complete pipes with two seperate cans. That is just one of the reasons they were fat and slow pigs (Huskies).

Baketech · 01-15-2004, 12:22 PM

big cube single = bifurcated exhaust ports

dB · 01-15-2004, 12:25 PM

Nice bikes, Conq!

In case I'm not the only one who had to look up "bifurcated":

bi·fur·cate ( P ) Pronunciation Key (bfr-kt, b-fûr-)
v. bi·fur·cat·ed, bi·fur·cat·ing, bi·fur·cates
v. tr.
To divide into two parts or branches.

v. intr.
To separate into two parts or branches; fork.

adj. (-kt, -kt)
Forked or divided into two parts or branches, as the Y-shaped styles of certain flowers.

SomeStrangeGuy · 01-15-2004, 1:41 PM

Quote:

Originally Posted by johnnycrash

Go look at any single cylinder thumper. They ALL have two headers coming from the cylinder head, but most combine into one tube that goes to one can. The CRF and YZF headers join immediately after coming out of the head. My KTM has two headers that join right before the can.

...the YZfours have a single tube/ two-bolt flange header, at least the one's I've owned have?

johnnycrash · 01-15-2004, 2:11 PM

Quote:

Originally Posted by SomeStrangeGuy

...the YZfours have a single tube/ two-bolt flange header, at least the one's I've owned have?

Then I guess I stand corrected. I could have sworn the YZF's had a two into one like the new KTM's. Memory is the first to go.

SomeStrangeGuy · 01-15-2004, 2:44 PM

Quote:

Originally Posted by johnnycrash

Then I guess I stand corrected. I could have sworn the YZF's had a two into one like the new KTM's. Memory is the first to go.

If it makes you feel better, you'll notice I mention nothing of the CRf, and you don't want me trying to explain any katoom details either for that matter

johnnycrash · 01-15-2004, 3:38 PM

Quote:

Originally Posted by SomeStrangeGuy

If it makes you feel better, you'll notice I mention nothing of the CRf, and you don't want me trying to explain any katoom details either for that matter

Looks like I'm wrong about the CRF as well. It has a single header tube also. I was thinking about XR's and my KTM - which have headers like this.

G-Force Junkie · 01-15-2004, 9:50 PM

RFVC= Radial 4 valve chamber or some such thing. Two exhaust valves, two intakes. All radialy pointed in at the cylinder making a pretty efficent "hemi" combustion chamber. If you ever have the vave cover off, its easy to see, sorta an odd rocker arm arangement, but it works great, and has since the early 80's.