| Author | Message | ||
     Jespo_m2 |
Hi, Just curious if anyone has tried adjusting the valve cable so that the exaust valve will leak... allowing alittle more flow at low RPMS. Putting an open pipe on the tubers made a big diff down low. It even allowed the bike to cruise at lower RPM's. I'm trying to get a little more flow while avoiding the noise. | ||
| Jos51700 |
It IS open at low RPM's. The valve closes in the mid-range, thus eliminating the mid-range dip in torque. You'll hear it get louder, quieter, then louder again, when you're standing next to it in a dyno cell. Fooling with the valve doesn't help much, it's a pretty good setup. I've wanted to retro one to a tuber for awhile now. | ||
| Jespo_m2 |
Interesting... are you 100% sure? What you say makes sense... just different from what I heard on the forum. | ||
| Jos51700 |
I find regular inaccuracies on the forum. (A couple of which have been my own). Just 'cuz it's on the net doesn't make it true. I prefer to go by what I've seen, first hand, whenever possible. | ||
| Bombardier |
+1 Jos. Closed at idle/ open at midrange / Closed at top end. | ||
| Jespo_m2 |
Now I'm really confused.  That is the opposite of what Jos stated. | ||
| Jos51700 |
I think he agrees, but misstated.....I think? | ||
| Dc29 |
Repair manual explains it. I had mine tied open after troubles with actuator. Sounded better stock exhaust, no noticeable power loss. I made a manual lever and cable to operate valve when I want to open and close it.Closed for traffic jambs and low RPM riding. Open time to rip...OH YEAH. | ||
| Jos51700 |
Open time to rip...OH YEAH. So, in other words, the best your bike ever operates is just as it did dead stock.... | ||
| Jespo_m2 |
Interesting Dc29... Nice to flip the switch when needed/wanted. Is the exhaust valve spring operated or does it need exhaust pressure? | ||
| Dc29 |
Exhaust valve is held closed by the spring that is in the muffler (can)stock. I fabbed a bracket to hold end of old throttle cable at the actuator end. Removed gears from inside actuator. Drilled another hole to attach cable to actuator. Ran this short cable out front side of translucent cover to old BSA bar mounted choke lever, it has enough travel to pull valve full open and resistance is ajustable so spring can't pull it closed when you wan't it open. | ||
| Jos51700 |
Sigh... | ||
| Jos51700 |
OKay, I'm wrong. | ||
| Dc29 |
jos51700 My bike never has had the various performance problems I read about on here other than an occasional cough rarely off idle. These are long stroke engines and low RPM and will never take a lot of quick throttle blip like I-4 engines do. Maybe it could run a little harder but at what cost, other problems I don't have now, heat, reliability, wear, more parts, lost in ECU land. 15000mi. So far I like it for what it is. Tourqe and FUUUUN.  | ||
| Jos51700 |
I've really mis-stated myself here. I was trying to say the muffler itself is open (high-flow) during low and high RPM, and closed off in the midrange. The valve is closed during the midrange. I'm a dufus for not being more concise, and I apologize. Perhaps this link below will clarify, although I personally feel that statements made in "paragraph 1" tend to disagree with the paragraph on the Rh side. I've ridden with airbox cover off, and it seems to me that the valve is always open at low RPM and high RPM, while closed in the midrange. Maybe I'm just of a heavy wrist. (It also seems like the valve is open at idle, and while testing the drive motor, it goes back to open), but according to the article, at low throttle/idle, the valve is closed. Dan Hurda knows more about than I ever will, so, he's more right than I'll ever be. Interpret it as you wish. http://www.147db.com/tech/the_power_of_muffler_bea rings.pdf | ||
| Jos51700 |
DC29, I don't disagree with your last statement. | ||
| Dc29 |
Good article there Jos51700. Just think of how many muffler bearings have been discarded with the addition of after market exhaust. Maybe thats where some of the problems start. I'll just continue to adjust mine as needed and be happy. Other than replacing tires often. | ||
| Miko_k |
On my 2004 Firebolt the valve is closed at all times, except WOT. So I don't buy the story with the "open @ idle, closed for midrange and open at top end". I've driven without the airbox cover and the valve opens only at WOT, even @ 1000RPM. It's a very simple servo that needs the white wire grounded and it opens. I have installed a pushbutton switch on my right switchgear and I can open it whenever I decide to be obnoxious. It's between the ON/OFF switch and the starter button: http://memimage.cardomain.com/ride_images/2/4833/4 881/24582440256_large.jpg | ||
| Dc29 |
Cool idea Miko. If I could get my servo to last more than a few thousand miles I would try that. | ||
| Miko_k |
It's the white wire that comes out of the ECM, between the two big connectors. Wire it through a normally closed relay(so the ECM can command the servo) as the middle(moving) terminal and have it switch to ground when the relay is powered. All done without even getting to the servo-removing airbox cover. The switch I got from radio shack and on the right switchgear there is a spare hole (like the one for the blinker on the left) so the switch fits there, I routed the wire in the loom with the starter wire for a complete stealth installation. | ||
| Growl |
Hello: The ECM has a built in "alternative program" for how the exhaust valve works. Thanks to Sekalilgai's pioneering efforts and subsequent reporting (link below) I have modified my exhaust valve's operation. http://www.badweatherbikers.com/buell/messages/142 838/375761.html Exhaust valve is now: 1) closed at below 900 rpm, thus allowing for quick starting. (same as stock) 2) Open at idle, thus having a deeper sounding idle. 3) Valve stays open from idle to 3300 rpm - great for cruising. Sounds deeper than stock, louder but not loud, like a BIG cat purring. Runs much smoother & is more tractable than stock. 4) Closed above 3300 rpms (unless throttle is opened wide, then the valve opens). This is like stock for this rpm range. This is where you lose torque if the valve is simply wired open. This mod plus little diddling with fuel values (thanks to a friend I met on Badweb) makes the bike run well from idle & up with 50+ mpg. (Message edited by growl on November 27, 2008) | ||
| Jespo_m2 |
Ah... yes... this is the info and feedback I'm looking for... All my tubers made great lowend lower when running a straight through exhausts. (V&H, D&D, etc). I dont see why this would be different. It's practically the same motor. Q: I have my air box cover off now beacause I'm waiting on my K&N air filter. When I retract the servo manually the cable bunches up... as if there is no spring on the exhaust valve. Is this normal or is my exhaust valve rusted shut? | ||
| Wantxbr |
could be the cable itself. You should be able to pull on the cable and it should pull back on its own. | ||
| Jespo_m2 |
Hmm. On my bike, when the bike is off the cable is extracted with the servo all the way to the right. If I move the servo to the left by hand, the cable starts to bunch up. So if the servo is all the way to the right... what position is the exhaust valve in? Open or close? |
