| Author | Message | ||
     Sparky |
I had an idea to mount a hotrod Electric Exhaust Cutout on the end of my S1's SuperTrapp after seeing and hearing some of these on the local rods around here. The only real questions were would it fit and would it work well? The answer to the first Q came from Quick Time Performance where their website had dimensions for their e-cutouts. The smallest one, for a 2 1/2 in. pipe, had a mounting bolt pattern that would just barely fit the bolt circle of the SuperTrapp discs. Cool! I decided to spring for one and try to make it fit. When the package arrived, everything was there, the e-cutout, toggle switch, extremely long wiring with quick-disconnect connectors and instructions. The first attempt to mount the e-cutout on the end of a stack of 12 discs showed a potential problem: the cutout motor stuck out far enough that the shock/swingarm pivot could hit it if the bike hit a big enough bump.  But if the e-cutout were mounted at an angle sufficiently so that the motor was positioned back more, there would not be interference with the shock when the wheel was bounced up as far as it could go. Cool! So an adapter had to be made. The adapter I used was cut from an exhaust pipe that already had a 3" flange for a 2 1/2" pipe welded. All I had to do was cut this off at the approximate angle to weld another 3" flange indexed precisely from the S-Trapp bolt orientation to keep the e-cutout motor axis horizontal. Note: an adapter like this could also be made from adjustable turnout kits from auto parts stores like O-Reilly's for about $24.  I also had to provide access holes in the adapter for the 6 S-Trapp mount screws.  Here's a layout of the parts involved. The last item is a really nice stainless steel adjustable turnout from QTP that I decided to use instead of the conical S-Trapp open-end disc.  This shows how thin the e-cutout is.  It all went together rather well.  The next thing was to wire it up and find a place to put the toggle switch. The wire harness had to be shortened and re-soldered to this connector for the switch.  The best place for the switch I thought was down by the ignition key switch just in front of it. So I made a bracket from a scrap piece of metal that already had the right size hole that would fit the bolt where the ignition key switch mounts.   So there it is.  How does it work? | ||
| Hybridmomentspass |
maybe im missing something....but usually cutouts are before the muffler, not at the END of it so in your case - what good does it really do by having it at the back of the muffler? | ||
| Mcelhaney14 |
It bypasses all the discs on the supertrapp. Looks good Sparky. | ||
| Sleez |
you may want to increase the number of discs on there, just to make sure you don't have too much BP with the valve closed. looks and sounds awesome!! great idea!!! | ||
| Robertb1958 |
I had Supertrapp "issues" on my X1 ran it for a while with no discs or innards, just an empty can. I think the bike runs a little better with 18 disks and the end cap after I fixed the issues than it did "open", but don't have a dyno run to verify. Bike has a Buell race CF air cleaner and race map, otherwise stock. | ||
| Koz5150 |
Nice project | ||
| Kc_zombie |
Pretty slick. | ||
| Sparky |
Hybrid, you're right as far as placement in an automotive application, but don't forget, a SuperTrapp has a closed end cap for a street machine. And like Mcelhaney says, the e-cutout when open allows exhaust to go straight through bypassing the restriction (and muffling) of the discs. Plus there's no convenient place to put it in front of the muffler on my bike. I hear you Sleez re the number of discs. I've experimented many times with more discs and what I've found with this relatively low HP engine (pre-Thunderstorm) is that with 15 or more discs, low end torque and throttle response goes away somewhat more than I like plus being noisier. Not helping too is that I had to replace a busted S1 cam with a set of 536's which seem to have slightly poorer low end throttle response than the stockers. So 12 gives a substantial boost in torque and throttle response below 4 grand with the valve closed. What's cool though is that the e-cutout can be slightly opened giving a little more noise while revving freer and reducing BP. Best of both worlds, eh? Yeah, Robert, I think you found out that these bikes like to have a certain amount of "restriction" in the exhaust for muffling but not too much for best overall performance. BTW, I did a shakedown run with the SCAB riders last Sunday up the mountains and over the Glendora Ridge Rd. Fortunately nothing broke or fell off and the e-cutout worked great. I noticed that with the valve closed there was usable torque from 2 grand up and throttle response was instantaneous but with the valve open (not surprisingly) it was really sluggish in that same RPM range until about 4 grand when it came more alive. | ||
| Robertb1958 |
Would be interesting to see torque and HP curves open vs. closed, for sure. | ||
| Coxster |
You could tap into the voltage fed to the needle of your tach, send that to a hi-impedance buffer (JFET input probably) and use a voltage divider pot to create a setpoint where a relay would open your cutout. You'd be in XB country then  Yes I have thought about this a LOT! | ||
| Sparky |
Good idea Coxster but sounds way too complicated for me to figure out. I was thinking to maybe tap into the VOES switch to trigger a relay that would open the valve when the VOES switches the ignition module to the retarded advance curve during heavy throttle applications. But one problem with that idea is that the e-cutout takes approx 4.5 sec to fully open, so there's a response time lag to consider. Robertb, I just may have to reserve some dyno time to document both conditions. One thing I'm kinda worried about though is with the valve open, should there be more gas flowing via an external jet in addition to the main jet to prevent a too lean condition? I guess some dyno tuning would confirm how much richer the mixture needs to be with the valve open. I have a vague recollection of an aftermarket enrichening device called ThunderJet which is able to provide a third fuel circuit on demand. If something like this could be made to work with the VOES switch, Coolio! Perhaps that problem would be solved. I love these projects. | ||
| Hybridmomentspass |
Id not considered the workings of a supertrap, now it makes sense. right on man |
