[mattsz]

My 2011 B5's auto-decompressor wasn't right from the beginning.  In trying to figure out how it worked, none of the photos and diagrams I found quite got the point across for me.  Last year, Gashousegorilla sent me some still photos of the parts which finally lit the bulb above my head.

This week, I found myself at my bench with an exhaust cam in front of me, so I threw together a little video demonstrating how the decomp works.  Experienced mechanics be warned - you won't learn anything from me!  But maybe this will help the new guys who are curious about how this device behaves.

5-minute video:

http://youtu.be/wU-QbPUCFxg

[adi-4004]

Great video! thanks.

[NorEaster]

Cool!

[wildbill]

matt
nice job - very well explained

[High On Octane]

Very cool Matts!  I was curious how it worked myself. 

[heloego]

+1 mattz! I'd been wondering the same, too!

Thanks! 

[singhg5]

+1 Very nice video, Matt

Are you going to remove auto decomp completely from your engine ?

[Grant Borden]

THANK YOY!!

The video also answered several questions I had about the decompressor.

Grant

[Scotty Brown]

Always a bit curious about this-----Thank you so much for a fine video explanation ---- Well done.

[gizzo]

Wow, nicely done, Matt! Thanks for taking the time to do that.
So I wonder what part is responsible for the clanking noise the UCE engine makes. Is it the exhaust lifter riding over that pin perhaps?

[mattsz]

Glad it's helpful, or at least interesting!

Are you going to remove auto decomp completely from your engine ?

I might.  My bike's decomp never acted right (noisy clatter when it shouldn't have), and I'm told that it may have contributed to carbon buildup issues.  A dealer "fixed" it - the noise went away, but so, I think, did the decomp function.    I'll decide when I open it up, once the weather warms up a bit.

So I wonder what part is responsible for the clanking noise the UCE engine makes. Is it the exhaust lifter riding over that pin perhaps?

That's the big question.  I've heard some say that the clatter is the flyweight cycling, but others have disagreed.  Now that I've examined the bits myself, I just can't believe that it could be the flyweight moving in the cam making all that racket...

[gashousegorilla]

 Nicely done Matt  And your hands and speaking voice were made for Video demonstrations.

[mattsz]

Nicely done Matt  And your hands and speaking voice were made for Video demonstrations.

Ok GHG, now I know you're screwing with me... 

[sparklow]

Nice video Matt. It is nice to be able to see the parts in action. As you may remember I have the same bike as you. The only time I have noticed a malfunction of my bikes auto-decompressor is on a start on a cold day. It has taken quite a while to disengage on these starts but otherwise it has functioned as designed.

[gashousegorilla]

Ok GHG, now I know you're screwing with me... 

  LOL !  Why ?!    I'm not kidding you.  I would have been fumbling and stumbling....  "where's that damn Allan wrench ! ".....This little PIA spring !"  And such. 

 It was well done.

[mattsz]

Damn - all those years I could have been raking in the big bucks as a hand model, wasted... 

[singhg5]

Nicely done Matt  And your hands and speaking voice were made for Video demonstrations.

These are Hurdy-Gurdy hands + fingers and vocal cords to match !   

Damn - all those years I could have been raking in the big bucks as a hand model, wasted... 

Matt - Now that you have started with this first video, many more to come and big bucks to follow !

[SteveThackery]

So I wonder what part is responsible for the clanking noise the UCE engine makes. Is it the exhaust lifter riding over that pin perhaps?

I'm certain that's what makes the hideous clanking noise when the decomp is in action.  When I saw the design I was horrified - it's a hell of a steep little bump that the tappet roller has to crash into and ride over.  Mind you, that's only my gut speaking - presumably somebody in RE did some sums and decided it was OK.

As I've said elsewhere, even with the decomp knobbled the bloody valve gear clicks and clacks away, making more noise than my previous two Bullets with manually adjusted tappet clearances.

[mattsz]

Matt - Now that you have started with this first video, many more to come and big bucks to follow !

I don't think I'll quit my day job just yet - besides, most of the good videos are already made... https://www.youtube.com/user/singh5g/videos