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[bikerboy53]

My BSR and I were out on a ride on New Year's Eve Day with some friends. We were wanting to get some miles on the new 120R motor we just installed in our 2010 CVO Ultra. We were putting along at about 35 or 40 mph when we heard a "klink" loud enough that the bike behind us heard it too. Power dropped off sharply, but the motor was still running. As I eased on a little throttle to try to make it to a wide spot, the motor backfired out the exhaust and died.

The push rod arm broke off the intake rocker arm on the front cylinder! The rocker arm only had a little over 400 miles on it when it let go. From the research I've done on this site, it seems like a fairly rare occurrence -lucky me! (Now if I could just win the lottery!) Thought it might be interesting to post a photo of the broken arm for those who might like to see it.

[prodrag1320]

check for coil bind,

[HD Street Performance]

Probably just a defective part
Some of the stockers I have been checking when converting to Baisley Corrected Geometry have had bad (loose) and or misaligned bushing line bore, easily fixed but not likely the cause here.

[HILLSIDECYCLE.COM]

I'd pop the cam chest open to see if anything is out of order in there, and as Kirby has already mentioned, valve spring coil bind, or collar to guide contact could be the cause.
Scott

[prodrag1320]

Probably just a defective part
Some of the stockers I have been checking when converting to Baisley Corrected Geometry have had bad (loose) and or misaligned bushing line bore, easily fixed but not likely the cause here.

could be,but ide check coil bind & like scott said,collar to guide

[sadunbar]

could be,but ide check coil bind & like scott said,collar to guide

Note that this is a stock 120r motor with T Man 662-1 cams.  There would have to be a manufacturing error for valve spring coil bind or collar to guide interference to occur.
 
Not impossible, but....  

I wonder if the initial pushrod adjustment was correct?    

Pretty rare failure.  Defective part certainly seems possible.

[Twolanerider]

Noted only as another data point for consideration; nothing more.  This past fall one of the locals had one of the same rocker arms fail about 1000 miles in to a 117 build.  No other internal issues were found during a thorough inspection of the top end and cam chest.  Repaired with a replacement of the broken part and a new pushrod and has approximately 2500 miles on it since.

[bikerboy53]

Thanks for the advice and ideas from everyone!

I did have them open up the cam chest to look for anything out of the ordinary, but they didn't find anything wrong in there. Oil pump still looks OK too.

I think it did give a couple of warning signs that there was a problem, but the mechanic didn't connect the dots in time. It was making a lot of tappet noise on one of the front lifters prior to the failure. I took it back and asked them to check it out. They adjusted the lifters and mentioned that the adjustment didn't seem to be working right -after turning the motor over a couple of revolutions, the adjustment was off by a small amount again.  Mechanic thought there might be a problem with the new S&S lifters...

It still made the tappet noise when they gave it back to me (before the arm broke), and when I asked about it they called it a "harmonic noise" and told me to go ahead and ride it. 

The new rocker arm seems to have quieted things down substantially, but it does have a little valve train noise at about 2100 rpm now. It seems to go away as soon as the engine gets away from that rpm -I think! I only had a short conjugal visit with the bike last weekend and I won't get it back until next weekend because they are ironing out a problem with the upgraded clutch. I'll know more in a few days...

As Twolane described it: I just wanted to put this out there for informational purposes only. I think there was a (fairly rare) problem with this rocker arm from the beginning and it died from a birth defect.

[HILLSIDECYCLE.COM]

FWIW, we use nothing but S&S roller rocker arms here.
As of yet, no failures with those.
I'd still put a close eyeball on that spring set-up, as long as is well in the cam chest.
Scott

[bikerboy53]

Note that this is a stock 120r motor with T Man 662-1 cams.  There would have to be a manufacturing error for valve spring coil bind or collar to guide interference to occur.
 
Not impossible, but.... 

I wonder if the initial pushrod adjustment was correct?      

Pretty rare failure.  Defective part certainly seems possible.

Sadunbar, Thanks for filling in some of the missing information for me. I think the initial pushrod adjustment was correct because there wasn't any tappet noise at first. After I put about 100 miles or so on it, the front cylinder started ticking (clacking). That's when I took it in for a checkup, and the rest is history...

I would expect a coil bind (or other similar) problem would have manifested itsself on initial startup. And I would think some kind of damage would have occurred to the pushrod or tappet or camshaft?

If it turns out I'm wrong, you guys will find out shortly after I do... 

[prodrag1320]

was probley just a parts failure (ive seen the SE`s break before),but also seen rockers break when your just under coil bind (like .010 or .015,thats why we use .060 here,some guys like to cut it closer),hard to tell when cranking a new motor & takes awhile for the prob to really manifest

[HD Street Performance]

Kirby, just a FYI
It is a 120r with SE springs, I am assuming stock MVA heads, coil bind occurs at about .735
I can check a set to be sure, I have a pile of those springs I have taken off and I used beehives from AV&V
I have seen them with nearly seized rear exhaust valves (at 10K+ miles), all carboned up on the port side and the stem, but not likely the case here.