Check Engine Light Code 21 - exhaust valve servo

[Deputybuzz]

Pulled a code 21 after jumping the diagnostics pins. Posted for some help on this thread: http://www.buellxb.com/Buell-XB-For...t-for-code-21...new-exhaust-the-cheapest-cure

Over the weekend I pulled the air box and checked the valve cable operated freely. When I the servo apart I found the gears had jumped from the spring loaded cam. The motor was still very warm from some trouble shooting cycles just minutes before but everything seems to work after rebuilding it. Seems to work fine for now but I expect it will fail again and eventually need to be replaced. Looked like the plastic was fatigued and slightly bent where the gear and spring loaded cam lock together.

Hope these pictures and this description are helpful to someone else.

 

[Deputybuzz]

By the way the pictures are before the servo rebuild. You can see where the white gear has a little hook on the top that receives the hook on the spring loaded black piece above it.

 

[powdr_dayz]

you could always just disable the servo (in ECMspy) and then tie the servo cable so that the valve in the exhaust stays wide open...

 

[Deputybuzz]

How much power is really lost by not having this servo actuate? Is it a power thing or an efficiency thing?

Had the servo not been so easy to fix I may have just locked it open and eventually found someone with some software to disable the valve.

Judging from the amount of heat on that servo motor, had I not fixed it immediately and ridden with it bound up, that motor would have smoked itself up in no time.

 

[jimijeans]

When you Accelerate the Servo opens the Exhaust valve to give you midrange power. When you Decellerate it returns the Muffler Servo Valve in the Muffler to proper position. The Complete Exhaust Actuator Box on top of the Inner Air Box is Kinda Expensive. Don't let anyone have your orignal.
They are fixable if you are cabable. The small motor gets hot and the cams are plastic. If you want Call Buellester Parts or American SportBike. You can just tie it open halfway and the Bike will run Although not properly. I wouldn't do that too long. Check the Small motor and the Curcuit Board to see if you can build one.
For completely Ridding you of the problem Kinda Expensive and TOO loud for some, A Nice Drummer SS along with American Sportbikes plug and go Emunlator for about 50bucks or so where the Box is so no code comes on. The Econo Drummer is pretty nice also. Kevin at KD fabrication can make you a DB Killer. There are other ways as well. It's actually cheaper to fix the Exhaust Actuator but they do fail Quite often. Usually it's the motor. Check around and good luck.*Jimi

 

[okey]

Well I opened mine up as I was getting code 21. The gears all appeared normal but couldn't be manually turned . I removed the motor (its a clean setup ) then could easily turn the gears . I removed a gear and reassembled the motor . The motor turns constantly when connected up . Does anyone know if I should be getting constant power to this motor and maybe the servo is not my issue or does it sound like the motor or pcb board inside the unit stuffed . I have heard the new servo motors are expensive but alas have metal gears and much more reliable . Any advice is welcomed . If I connect the unit up as normal it just locks up and wont turn at all . I know about an eliminator but want the bike as stock as a rock so will replace the unit if required . Cheers for any help

 

[okey]

Had a bit of a play and managed to get the motor to stop by turning the actuator into a position that zero'd the potentiometer I guess . I would have assumed the motor would turn in either direction to open / close but this is not the case with mine .When I rotate the metal pull the motor starts I keep opening and it stops at a certain point then when I go further in the same direction the motor operates again in the same direction .I found the main cam gear (white plastic one ) is slogged out on the shaft allowing the gear to float too much causing the initial issue . Does anyone know how these servos operate incase I can repair this one for future use ? cheers for help . btw I have pulled my cable open and there would have been no load on this unit when it shit itself .