Butterfly chatter

[genzer]

What is it and what causes it?

[kd]

Need some info. What is this on and what modifications?  Sometimes cam timing or low idle speed.   What breather are you using?

[genzer]

It's a 16 tc  with cams headwork 2 into1 and screaming eagle ac, you might remember a post I had about changing baffles and some oil leaking from the ac.  Made a few changes from t-max  and now every twist of the grip I get the knock knock unless I let off alittle.

[kd]

It sounds to me like you may be rolling it on at too low of an rpm for the cams you are using and the compression.  What cams are they?  It may be cam overlap signal (like standoff) in the manifold that is exaggerated by the opening of the throttle.  The stock breather design will mask some of those sounds but a more open performance breather lets you hear it all.  What RPM is it noticeable at and what rpm do you have to be at to not have it happen?

[Deye76]

"Made a few changes from t-max  and now every twist of the grip I get the knock knock"
I'd get it on a dyno.

[genzer]

I'd,  cr 575 10:25:1and most no below 2500, going to put a couple hundred miles on and see if the autotune correct's some of it.

[Tireman]

I'd,  cr 575 10:25:1and most no below 2500, going to put a couple hundred miles on and see if the autotune correct's some of it.

NOTE: I like Cyclerama cams and in no way degrading them in this post!

I find this very interesting and I was curious to see what cams you used because I have the same "butterfly chatter"!!
I bought my 2011 TG 103" 6/2019. Found out it had S&S 551G cams that ran out way to quick for me so Mega Flo ported the heads square up the cylinders and went with KB +.010 pistons. I contacted Wes @ Cyclerama and surprisingly he had a set of CR 575 in Gear Drive!!
Jim set compression for the CR 575G @10.1, I added a S&S Stealth AC. At that time I noticed the same "butterfly chatter" as you describe and it was pretty loud! I haven't tried correcting it.
Fast forward to 1/2021 it is now an 117" S&S crank, with Mega Flo ported CVO 110 heads, 575G @10.25, 58mm TB. I added the 1" taller Stealth filter and the chatter is still there however less noticeable, I believe because of the 1" taller AC. It doesn't bother me as it's only does it at very low rpm then it's gone and the trike runs amazing! Curious to see if you get it to go away though.
Good luck!

[genzer]

Tireman, yeah I'm happy with the cams and I forgot to mention it also has a 58 mm tb, here's where things get muddied. I had problems with reversion when I switched baffles, I sent data collection to t-max and they suggested 5.3 injectors,  increasing cranking fuel pressure and tuning percentage from 9-11 percent. Then I accidentally ( dumba$$ ) instead of clearing dtc hit all learned values So I'm thinking just ride it and see if relearning helps.

[Tireman]

genzer, mine did this with both stock and the 58mm throttle body. However I'm running the 6.2 injectors that Dave at JD Cycle Works recommend because he tuned it. I never mentioned this to Dave but since you started this thread I might call and see what he says. He might have a solution!

[Don D]

Do you have servo throttle control? Any cam with overlap exaggerates the sound. An air breather that is open same comment.  Take the AF off and at idle put your finger on the plate, bingo, noise gone.

[kd]

   That's where I was going with my earlier reply Don but the conversation started to veer off a bit on tuning.  Pulling the filter as you have suggested is a good way to confirm it's happening.  I expect the reason Tireman feels it may have got slightly better with the 1" taller filter is the resulting louder "hiss" from the less restrictive intake is now covering over or masking the clacking. 

[Tireman]

I understand the clatter is still there with the 1" taller filter just stating it is less noticeable. Mine doesn't make the noise at idle. Only on low rpm acceleration. It might not even be the same noise for that matter. It doesn't affect the performance at all.

[kd]

Exactly, and low rpm acceleration is accomplished with the throttle blade barely off it's seat.  FBW throttles do not have a cable stabilizing the blade.  My point is that the 1" taller filter emits more intake air movement sound.  That may be masking the clacking you hear (which is more of a mechanically produced sound from the throttle blade).   Kinda like trying to hear someone whisper the secret clue in a TV murder mystery when the fan in your hotel room heating system cuts in. 

[Don D]

 
Reversion is present, the manifold acts in a way similar to a musical instrument. It is similar to Mikuni slide rattle.
Cable control and an IAC and most of that goes away.