The following dyno runs were all performed on the same Dynojet 250 dynamometer. Although not
possible to perform on a single day, the graphs are all SAE corrected and whether conditions were similar.
The engine is a 1200 cc XR1200 motor with Zippers 575XR cams, Wiseco pistons, a 0.020 metal
layered head gasket, and CNC ported heads (by Zippers). Custom length one-piece pushrods are used. The airbox
uses a custom oversized K&N air filter and internal obstructions in the airbox have been removed to improve air flow.
The head breathers and crankcase breather have been externally routed. Primary gearing has been changed from 34-57 to
38-57. The 28 tooth transmission pulley has been replaced with a 29. The rear 180 stock Dunlop tire has been replaced
with the 190 racing Dunlop tire. (5th gear gearing for the dyno runs is altered from 4.071 to 3.414.) There are
a few other minor engine tweaks, but these are the more major.
Before the engine build the peak power of the tuned engine was about 70 ft-lbs of TQ and
85 HP (with stock gearing). After the build, depending upon the intake and exhaust configuration, the engine is capable
of about 90 ft-lbs of TQ and 100 HP (with its altered gearing).
All dyno graphs for all exhaust systems were done with this engine build.
OEM HD Exhaust System for XR1200 vs JOEP Special 2-into-1
The first dyno graph shows a comparison between the XR1200 with an unmodified OEM exhaust system
(RED) against the JOEP Special 2-into-1 (BLUE).
D&D 2-into-1 Header with Special Exhaust Can vs JOEP Special 2-into-1
This graph compares the D&D exhaust header from their 2-into-1 Concentric Baffle exhaust system
for the XR1200 (RED), and the JOEP Special 2-into-1 (BLUE).
In early testing of the complete D&D Concentric baffle 2-into-1 exhaust system, it was determined
that the Concentric Baffle exhaust can, was not a peak performer. However, the D&D 2-into-1 exhaust header for the
XR1200 was well-designed. Therefore the Concentric Baffle exhaust can was swapped for a special exhaust can from another
manufacturer. This graph therefore shows what is possible with the D&D 2-into-1 header with another exhaust can
- which is better than the production D&D Concentric Baffle exhaust system. The D&D Concentric Baffle exhaust
system would post lower numbers.
Unfortunately, the only dyno graphs that I have comparing the different trials of the complete D&D
system are from another dyno, and not directly comparable to this one. And, I no longer have access to the D&D Concentric
Baffle exhaust can, to do a direct comparison of production systems.
This graph shows the performance of the JOEP Special 2-into-1 system, against a variant
of the D&D system which actually performs better than the D&D production model.
|D&D Special to JOEP Special
Termignoni Trophy Race 2-1-2 Exhaust System vs JOEP Special 2-into-1
The graph shows a comparison between the Termignoni 2-1-2 Trophy Race exhaust system (RED), against the JOEP Special 2-into-1 (BLUE).
This graph shows the Termignoni, without its "db Killer" noise silencers (RED).
|Termignoni to JOEP Special
Torque Hammer 2-into-1 Exhaust System vs JOEP Special 2-into-1
The graph shows a comparison between the Torque Hammer 2-into-1 exhaust system (RED) against the JOEP Special 2-into-1 (BLUE).
This is for the standard production Torque Hammer, without its noise silencing baffle.
|Torque Hammer to JOEP Special
Vance and Hines Widow 2-1-2
Exhaust System vs JOEP Special 2-into-1
The next graph shows a comparison between the Vance and Hines Widow 2-1-2 (black street version) exhaust
system (RED) against the JOEP Special exhaust (BLUE).
The Vance and Hines has one of the best overall performance curves for a built XR1200.
|Vance and Hines Widow to JOEP Special
JOEP Special 2-into-1 with TQ Cone vs JOEP Special 2-into-1
The next graph shows a comparison between the JOEP Special 2-into-1 with some minor pipe tuning using
a TQ cone (RED) against the JOEP Special exhaust (BLUE).
For the TQ Cone run I used a single cone approximately 3/4 the size of the single outlet pipe, inserted
about 2" into the exhaust tip. I did allow the TMax to re-tune the fuel offsets, but did not try multiple variatioins
in terms of the size of the TQ Cone or distance that it was inserted into the pipe.
The TQ Cone did actually quiet the pipe slightly, but I did not take a dB rating of the difference.
There is likely more that could be done for the performance of the JOEP by trying different sized TQ Cones.
NOTE: After the dyno runs with the TQ Cone, I noticed that the exhaust header flange nuts had
started to loosen up. This may have contributed to the roughness in the TQ Cone dyno curves.
|JOEP Special with Torque Cone vs JOEP Special
At about ???? lbs (with mounting brackets), the JOEP Special is one of the lighter exhaust systems
for the XR1200. It's style is very drag pipe like, and it is one of the loudest exhausts for the XR.
For a short little sawed-off exhaust, the performance characteristics were surprisingly good, and
better than many other production pipes.
Since the JOEP is based on a cut down OEM exhaust header, installation is straight forward. Due
to the tight fit of the header tubes in the Y pipe though, it was a bit difficult to get the alignment of the pipes right,
and ensure clearance with the engine case. A little finesse and some spray lubricant helps.
The pipe also needs a lower engine exhaust support. The stock mount will work. To save
weight, I used a short standoff that I fabricated from 3/16" x 1" flat bar stock.
The placement of the retaining spring mounting clips on the engine side of the pipe leaves the external
view of the pipe clean, but does make installation of the springs a little difficult.
The black finish of the pipe still needed to bake on. This was not a problem, but it does mean
that the paint will be a mix of slightly glossy, and dull black, depending upon how pipe heats at different points.
Once baked, the paint seems durable. Prior to that, however, it is easily scratched.
Surprisingly, it is not radically louder than other performance pipes. It runs about 103dB at idle
(1000 rpm), 1 m from the pipe tip. This drops to 99 dB at 2m. Of course, at 3,000 rpm it jumps to 113 dB at 1m and 109 dB
at 2m. This does make it about 1 dB, or about half again louder than the Vance and Hines Widow and Termignoni exhausts. It
ends up being about equally as loud as the D&D header pipe with the special race exhaust can that I sometimes run.
The JOEP Special 2-into-1 was a surprisingly well performing pipe. I had not expected
much out of it due to its short length and lack of an exhaust can - but it will run with, and outperform some of, the
better pipes on the market. For a rider who likes its style and doesn't mind the noise, the performance will