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I'm sure this has been touched on but can't find it on "search". I have a 1977 R100S with the second crossover behind the transmission. Do I need to reinstall that if I have the front crossover in place? Different running???

If you have the holes in the exhaust pipes for the crossover then you will need to install one. Unless you wish to make a whole lot of noise.

No! This is a new (free) pipe that does not have the connection capability.

tomjohnston wrote:No! This is a new (free) pipe that does not have the connection capability.

"pipe" ?

Do you mean headers with just a front balance tube?

My RS had a single front balance tube until I put s/hand headers with two crossover/balance tubes on the bike.
I didn't notice any difference. It certainly won't hurt your bike.

tomjohnston wrote:I'm sure this has been touched on but can't find it on "search". I have a 1977 R100S with the second crossover behind the transmission. Do I need to reinstall that if I have the front crossover in place? Different running???

Use either system Tom. Both are compatible.

The "balance" pipe (cross-over ) at the front
is designed to provide extra expansion area for the exhaust pulse,
effectively making the exhaust system volume larger and changing torque delivery characteristics.
i.e. more torque is delivered at low to mid RPM than without the cross-over.

The second cross-over, added in '81 (?),
was intended to compensate for EPA mandates
that otherwise might have compromised power delivery
by boosting torque delivery even further and over an even larger (frequently used) RPM range.
Placement and number of cross-overs will affect the "shape" of the torque delivery curve.

Udo Gietl experimented both with the number and placement of cross-overs
with positive results,
but ultimately got rid of all of them –
Seems that he favored a stepped header (forerunner of today's tapered header)
claiming that this technique improved torque delivery throughout a wider range of RPM
than was practical or possible with cross-overs.

A well designed 2-into-1 system essentially does much the same with it's large diameter secondary.
Lengths and diameters of both primary and secondary pipes will be critical
to resultant torque delivery / performance characteristics.

EXCELLENT ! Thanks. I knew the value of the first crossover since I had tried running without it on another bike. My concern with the second crossover was if it would ruin the "friendly" power delivery without having to rejet or re-adjust the stock carbs. The messy plumbing inside the aircleaner box was removed without noticeable problems so I hoped for more of the same. I will give this setup a try. Thanks Again TomJ

I think mostly you will enjoy the relative ease of assembly.

justoneoftheguys wrote:I think mostly you will enjoy the relative ease of assembly.

Yeah, twin balance pipes suck.
Now I have to disassemble the whole exhaust system to change my oil filter. (RS with crash bars and oil cooler)
Previously with a single pipe, it was a matter of undo muffler mounts, engine mount clamps, star nuts, and slide the whole shebang forward a little and down a little.

ME 109 wrote: Yeah, twin balance pipes suck.
Now I have to disassemble the whole exhaust system to change my oil filter. (RS with crash bars and oil cooler)
...

?? Must be the crash bars, then ...
I've never had to remove any exhaust parts for routine maintenance on an RS.

Removing the exhaust header system was a bit of a pita compared to the single, though,
it could be dropped to the floor, but then was ensnared by the center-stand.
If the header needed to be "put on the bench", it had to be split into 1/2s.