Since day one, my 120ST has been noisy on the top end and was very prominent when hot... especially between 2600-3000 rpms. I was told it was NORMAL and had dealt with it day by day.... I wasn't buying it. There is no way I should here top end noise at 80mph over an Arc XDI 600.4 amp pushing 4 high-end speakers.
I found out about ROCKOUTS
on another forum a few months ago and decided then, that this could be a viable solution ( to correct a potential problem ) that I 'might' be having.
It never got better or worse... so I bought the $15 rockouts and hung them on the bench in the garage for a rainy/snowy day.
I picked up some adjustable pushrods and yesterday decided to tear into it... GLAD I DID!
Once I got in there ( following the manual ) and took the rocker support housing off the rear cylinder, it was obvious that 'something' just wasn't right.
First clue was the right side bolt on the exhaust side.. VERY HARD to get out compared to the other 3
Second clue was the offset position of the rocker shaft itself...
Third clue was noticed looking into the bolt hole of the rocker support....
Fourth clue was the rocker shaft when I pulled it out of the housing with very LITTLE effort.... witness marks from rotational action
( they are not supposed to move this easy )
Here is a video...
Rocker Shaft Video
After finding all this... I called my HD tech and sent him pics... and told me to bring the parts in for inspection... afterall... only 3000+ miles and still under warranty ( I was 'cleared' by HD on this before I started )
Everything was within tolerances but it was clear to them that this had to be what we were hearing in the top end.
They agreed with me installing the Rockouts should cure the issue of the shafts bouncing off the bolts and moving around during operation.
After cleaning up and re-installing the shafts and aligning them, I installed the kit with ease... instructions are perfect and very simple.
Here you can see the ROCKOUT inserts installed.
I reassembled the rear cylinder with the new SE adjustable pushrods and took the advice of my HD tech to go 3 full turns on the rods vice 2.5 as stated in the instructions. He said the tighter tolerance will run better and quieter.... he has been an HD tech for 15+ years, so I trust him.
I did the front cylinder and found the same issues....
Got it all back together... and......
WOW!!! I have NEVER heard my 120ST so quiet since day one!!! Every bit of noise I was hearing is GONE! I ran it up to around 285 degrees at idle to get the oil nice and hot and rev'd to 2600-3000 rpms where the noise was most prominent... NOTHING AT ALL!!!
I couldn't be happier at this point! Gonna be takin er out today for a ride, so that will be the ALL-TELLING truth.....
Just wanted to share this with the masses.