| Author | Message | ||
     Ratbuell |
So, before the 3 hour slab ride from home to Pocono for 1125r class a couple weeks ago, I installed more discs (from 11 to 24) and the endcap on my S2. Trying to cut down on highway drone. Bees...get these bees out of my helmet....bzzzzzmmmmmmmmmzzzzzzzzzz Bike ran fine on the slab, no issues at all. And it *was* quieter at cruising speed - I could actually hear my iPod. Now that I'm home and running my "normal" pace (i.e. WOT from time to time, merging, just having fun) I notice a distinct lack of top end power, say....above 4500 or so. Since my mechanic is a moron (points at self) I think "5k miles, rings are going bad, motor's coming apart, wasn't assembled right, argh". Nothing has changed...except the endcap and discs, I realize during lunch. So, I pull the endcap off tonight before riding home. Voila! Top end (and highway drone) is back. I thought someone said Supertrapps were supposed to work better with the endcap on and a lotta discs? Anyway. If anyone has a spare endcap (says "spark arrestor" on it) or "race" endcap with the hole in it, let me know - I'm interested. I want to open it up and have the guys in the machine shop weld a turnout on it so I can at least keep from carbon-ing my nice, white, rear Marchesini. The noise I can live with around town...and I changed to a "quick change" setup. Three bolts (every other one) hold the discs in with blue loctite on the threads. I drilled out every other hole on the endcap large enough to go over the bolt heads on the discs, so I can use three bolts to hold the endcap on if I have a long highway trip ahead. I'll do the same on my turnout endcap when I get it made. Presto - exhaust that changes as quickly as the home-made quick release wing-nutted "T" lower fairings  And I'm hoping with the turnout I'll be able to point the drone away from my helmet and into the pavement. | ||
| Onahog |
Joe... I run 12 discs in mine with a home made turnout..Works great... I used one of the race caps with the hole, and a turn out tip {stainless} which I robbed from a Honda dirt bike... Welded it up at about a 45 degree angle.. 90 degrees would be sideways... Works great all around and not super deafening... I can sen picture it if ya like...Hankb | ||
| Onahog |
Turn out trapp  | ||
| Whosbeenfartin |
I have a supertrap on another bike (not a buell) and I can't tell the difference between having no endcap and no disks and having the race encap in (discs or no disks). I would suggest you try no endcap and if its the same then you could make a turnout out of one of the discs. | ||
| Warlizard |
I find it odd that bike got quieter w/ more discs? I have found just the opposite to be true. The race only end cap is available from the DS Fatbook- I think about 15$. Consensus is that 20-22 discs is optimum. | ||
| Nevrenuf |
21 discs with race endcap and motor work makes for a nice bike. i'm no mechanic by a long shot but if you don't have any engine work done to it that might make a difference either way when my bike gets out of the shop i'll have it dynoed to make sure it will do all that it can do. have you ever had it dynoed. | ||
| Ratbuell |
Haven't had it dynoed yet. Bike is stock bottom end, Thunderstorm top end, Lightning cams, race ignition, jetted appropriately. It has *noticably* more top end with an uncorked exhaust, nearly the same difference as having a main jet one step too small. The "quieter" didn't come from the more discs, it came from the addition of the endcap. I was running pre-trip with 12 discs, no cap. For the trip I added some discs for breathing, and put on the endcap. You're right - more discs = more noise...if you have an endcap. I don't think it makes a lick of difference how many discs you have if you don't have an endcap though. Hank - thanks for the pic, that's about what I'm looking to do. | ||
| Loki |
from the 'Trapp site Q. How many diffuser discs should I run? The answer depends on your displacement: disc diameter, power band, and noise level. Fewer discs reduce sound levels, more discs increase sound levels. Fewer discs increase low-end torque and richen the carbureted fuel mixture. More discs increase sound levels, increase top-end power and lean out the carbureted fuel mixture. NOTE: When tuning an exhaust system, start with fewer discs and add. Never start with a lot of discs and subtract. Generally on a stock set up (no engine modifications, and stock carb and air filter), you can start with six to eight discs on dirt bikes and ATVs. On V-twin, metric and cruiser bikes, start with twelve discs. A popular misconception: The more free-flowing an exhaust system is, the more power it will make. This is not true. Some backpressure (2-3 PSI) is necessary to achieve maximum power. This is why it is necessary to use the discs that come with your tunable SuperTrapp exhaust. The number of discs to use will depend on your application, displacement, disc diameter and power band. To assess the performance of any product that affects horsepower and torque, lap times and Dyno- runs are your best indicators. However, since most enthusiasts usually only have a “seat-of-the-pants” Dyno, running condition is the most obvious indicator. Pay attention to the coloration of the discs. Little or no disc coloration indicates a possible lean condition (remove one or two discs). Black or sooty discs are indicative of a rich, or oil burning condition (add one or two discs). Discs that turn a tan or golden color indicate an acceptable balance of fuel mixture and exhaust flow. Reading a spark plug is the quickest way to check if everything in the engine is working as it should. And, it will tell if the SuperTrapp has been tuned properly. A rust-brown spark plug color indicates that the plug is operating smoothly (exhaust is tuned correctly). A whitish look indicates that the burn is too lean (remove one or two discs). A blackish deposit on the plug electrodes (left by oil or fuel traces) indicates that the burn is too rich (add one or two discs). They have a forum just for this type of discussion | ||
| Easy_rider |
That's awesome, Loki. I never would have thought the color at the muffler would be indicative of the mixture. Makes sense, though. |
