How important is the exhaust crossover pipe?

[Grimly]

Probably not necessary. You could probably do the same thing on the other end with crossovers on the sync ports between 1-4, 2-3, on the carburetors. It does make a small difference , especially in low end. Triumph and others have done the same with their carburetors.

Supposedly the reason for the YICS system, that I've been blessed with on the XJ - only means I have to acquire a special tool now to set the carbs up. Blocks to them.

[Brendan W]

At one time Honda said that 40% of all their computer time in r&d was on exhaust tuning. The general idea was to have the shock waves from an exhaust valve opening reflected back to another exhaust valve at just the right time to reduce spillover of fresh charge air before the valve was physically shut. Crossing and fitting joining pipes gave more possible pathways and flight time durations for this effect to happen. I imagine it was more important for two strokes. The Z650s had some models with crossed headers as Steve mentioned which if you believed the published graphs gave a bit more mid range torque at the expense of a bit of top end. I had one of those crossed 650s and replacing the exhaust the only difference I could tell was the sound.

[JEEPRUSTY]

William Carlos Williams, "so much depends"

---

so much depends
upona rusty crossover
pipe
glazed with rain
water
beside the white
chickens.

[Brendan W]

I don't know why, but this popped up immediately.

I have eaten
the plums
that were in
the icebox

and which
you were probably
saving
for breakfast

Forgive me
they were delicious
so sweet
and so cold

[nejeff]

Just ask for a couple of pipes that are 1 1/4" diameter, 7" long, have them expand one end for about 1 1/2-2". Expand it just enough to slide the other pipe in. When you get home, use a hacksaw to cut some slots about 1" deep on the expanded end, then slide everything together and clamp it up. If your stock clamps are still good, use them. They take a LOT less room than a typical muffler clamp, which will hang down below the bike and get damaged by road debris.

Print out the pictures to show them what you are trying to do.

.

Are yours steel or aluminum?

[nejeff]

Bringing this thread back to life once again. I "exhausted" all local muff/exhaust shops, no one has 1 1/4" pipe. I have ordered a length of it off of Ebay. Also no one I have talked to locally has the ability to expand the pipe so I bought a cheap Harbor Freight small pipe expander which I hope does the trick.

When this is done then the carbs will need re-synced correct?

[Agemax]

changing your exhaust does not require a carb synch

[geol]

http://www.cycleworld.com/2015/06/26/ask-kevin-why-do-my-exhaust-headers-have-crossover-tubes

Sooooo much, well BS loaded into one thread I thought I would add a bit more hehe

[Wingsconsin]

If the crossover is important ..
then why not build a new 'H' box of pipe 1-1/2" diameter

1 1
1-1
1 1

What a great illustration ... ha ha ha

[Buffalo Bill]

William Carlos Williams, "so much depends"

---

so much depends
upona rusty crossover
pipe
glazed with rain
water
beside the white
chickens.

Lovely.
----------so much depends
on winning this debate:

I have eaten
the plums
that were in
the icebox

and which
you were probably
saving
for breakfast

Forgive me
they were delicious
so sweet
and so cold

[nejeff]

Lovely.
----------so much depends
on winning this debate:

I have eaten
the plums
that were in
the icebox

and which
you were probably
saving
for breakfast

Forgive me
they were delicious
so sweet
and so cold

Hey, where the hell is Jeep Rusty anyway? Haven't seen him around lately.


Wing I think I would rather just slip in a couple of pipes and call it a day

[Cipher]

Were the crossovers used for any real power gain or just to eke out a bit lower emissions for the EPA?

[TxGSrider]

On a car a crossover can increase the torque, but I suspect on a twin or four even, that it lowers the sound by letting the sound waves cancel each other out some.

[Steve]

... I suspect on a twin or four even, that it lowers the sound by letting the sound waves cancel each other out some.

I have mentioned in another thread that when I changed a couple bikes to run without a crossover, the overall sound level did not change, just the sound. The cadence changed a bit, but it sounded just like a '79 850, instead of an '81 850.

.