Author Topic: Rocker arm shaft blew out the side (Read 2703 times)

dazemc · « **on:** July 04, 2020, 11:38:00 PM »

Okay well I thought I could hold off on tearing into the top end. I looked up and down the road for that cover but I can't find it so I'll need to order a new one. I caught it quick and maybe lost about a quart of oil. What other damages should I be prepared for?

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bryanj · « **Reply #1 on:** July 04, 2020, 11:39:30 PM »

A rocker will have fallen off the shaft

754 · « **Reply #2 on:** July 04, 2020, 11:46:42 PM »

What did that sound like, it may have beaten the hole oval as it came out.

dazemc · « **Reply #3 on:** July 04, 2020, 11:55:09 PM »

Quote from: 754 on July 04, 2020, 11:46:42 PM

What did that sound like, it may have beaten the hole oval as it came out.

I lost power and I pulled off to switch to reserve. Obviously low fuel wasn't my problem and I could hear the cam chain very clearly. If there was any noise before that I didn't hear it. I have a camera that was running that I'm going to see if I can hear anything on. Between feeling loss of power and pulling off to kill the motor was less than a minute so I didn't really get a chance to listen.

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dazemc · « **Reply #4 on:** July 04, 2020, 11:55:54 PM »

So, who sells good upper end rebuild kits?

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bryanj · « **Reply #5 on:** July 05, 2020, 12:09:35 AM »

No such thing as a rebuild kit. Gasket kits now tend to be complete engine and you probably need a new cam cover, all 500/550 from 71 to 78 will fit but up to 76 can wear the spindle holes whilst 77 and 78 were modifield.

dazemc · « **Reply #6 on:** July 05, 2020, 01:31:43 AM »

Quote from: bryanj on July 05, 2020, 12:09:35 AM

No such thing as a rebuild kit. Gasket kits now tend to be complete engine and you probably need a new cam cover, all 500/550 from 71 to 78 will fit but up to 76 can wear the spindle holes whilst 77 and 78 were modifield.

I'll be getting in there tomorrow or the day after so you'll probably be hearing more from me soon. But worse case scenario I'm looking at what? Replacing the entire head?

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754 · « **Reply #7 on:** July 05, 2020, 02:12:53 AM »

Stick the rocker shaft part way and give it a wiggle and tell us what happens.

bryanj · « **Reply #8 on:** July 05, 2020, 02:54:43 AM »

Nope cam cover and valve(s) maybe

Scott S · « **Reply #9 on:** July 05, 2020, 03:42:23 AM »

I'd be worried about that cam lobe, too. If the rocker is off the shaft and the cam is trying to lift the rocker, what is happening in there? Beating it around?

dazemc · « **Reply #10 on:** July 05, 2020, 12:42:54 PM »

Quote from: 754 on July 05, 2020, 02:12:53 AM

Stick the rocker shaft part way and give it a wiggle and tell us what happens.

The rocker shaft was out a little bit more than it is now and I pushed it in more. Doesn't wiggle a bit.

Quote from: bryanj on July 05, 2020, 02:54:43 AM

Nope cam cover and valve(s) maybe

Yeah I'd be lucky if the valves were not being slammed by the piston.

Quote from: Scott S on July 05, 2020, 03:42:23 AM

I'd be worried about that cam lobe, too. If the rocker is off the shaft and the cam is trying to lift the rocker, what is happening in there? Beating it around?

I'm fully expecting to see the lobe, rocker, and valve cover scored to hell.

So I was briefly searching the forum and I came across someone tryning to install pinned rocker shafts. Is this still, or was, a viable option?

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dazemc · « **Reply #11 on:** July 05, 2020, 03:10:19 PM »

First signs of damage

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seanbarney41 · « **Reply #12 on:** July 05, 2020, 03:30:43 PM »

You may not be that bad off...I have seen caps damaged worse from just the nut coming loose. Remember, a rocker without a shaft probably isnt going to open a valve...unless some sort of freak jam up happened.

dazemc · « **Reply #13 on:** July 05, 2020, 04:08:16 PM »

Quote from: seanbarney41 on July 05, 2020, 03:30:43 PM

You may not be that bad off...I have seen caps damaged worse from just the nut coming loose. Remember, a rocker without a shaft probably isnt going to open a valve...unless some sort of freak jam up happened.

It looks like I did get lucky. The rocker was cocked sideways a bit and they both appear to be unscathed. Slight damage on the cover.

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754 · « **Reply #14 on:** July 05, 2020, 04:12:07 PM »

Hard to say, get another rocker ready to ship. Hope no chunks broke around the rocker shaft hole, roll the shaft on glass, see if it bent.
Might have chipped rocker or cam, you can pull it apart in frame, may as well get ready .

dazemc · « **Reply #15 on:** July 05, 2020, 04:12:17 PM »

Anything look out of the ordinary? Valve guide looks good but that doesn't mean the seats are good. Any easy way to check the intake valves without pulling the carbs and intake?

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754 · « **Reply #16 on:** July 05, 2020, 04:14:00 PM »

Fack that was 7 seconds ..?..a new 500 rocker cover removal record !

754 · « **Reply #17 on:** July 05, 2020, 04:18:28 PM »

Cam top left pic, looks like edge pushed over , makes nothing will come of easy. , some wear on the hard fave on the side of rocker, but if you mainly want to get thrubthe season it looks like you can use it, better than I expected

dazemc · « **Reply #18 on:** July 05, 2020, 04:20:55 PM »

Quote from: 754 on July 05, 2020, 04:14:00 PM

Fack that was 7 seconds ..?..a new 500 rocker cover removal record !

Haha I like caffeine but really these swivel head drivers are awesome

Looks like the other shafts were starting to work themselves out too. (EDIT: I initially thought the shafts were pressed in. So they can't work themselves out.) I tightened the cam chain tensioner not too long ago. Could a worn tensioner have caused this or am I missing something here?

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dazemc · « **Reply #19 on:** July 05, 2020, 04:29:23 PM »

Quote from: 754 on July 05, 2020, 04:18:28 PM

Cam top left pic, looks like edge pushed over , makes nothing will come of easy. , some wear on the hard fave on the side of rocker, but if you mainly want to get thrubthe season it looks like you can use it, better than I expected

Yeah I noticed the edge has a brand new bevel lol. I've taken apart a 78 cb400t twin and this looks pretty much the same +2 cylinders. Loosen cam chain tensioner, two bolts that hold the retainer and then twist and pull the cam lobe?

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dazemc · « **Reply #20 on:** July 05, 2020, 04:38:14 PM »

6mm bolt somewhere on a 71 CB500 that I can use for these rocker shafts?

EDIT: Nevermind, literally all the bolts I just took off

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dazemc · « **Reply #21 on:** July 05, 2020, 06:06:29 PM »

The guides for the shaft are are a little bit tight at the end nearest #2 cylinder. I swapped shafts just to confirm it was the guides and not the shaft. Rolls flat on glass but just wanted to make sure. I can press it in with a few light taps of a rubber mallet but it doesn't spin freely anymore. Looking through old posts about rocker shaft wear makes me wonder if it even matters that it won't spin. The two rockers slide freely on the shaft so I'm not too worried about it. I'm still ordering a valve cover either way. I am curious if there is a fairly easy way to lock these shafts in place?

Really my biggest question is, how did this happen and how can I make it not happen again?

EDIT: I'm waiting for someone to tell me I didn't have the end cap torqued down enough 🤦‍♂️

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bryanj · « **Reply #22 on:** July 05, 2020, 11:54:45 PM »

It happened cos the end cap fell off. Was the screw missing or broken, if missing not toght enough.
Remember the soft alloy washer between the steel bracket and cam cover or you will have an oil leak.
I would reuse all of that, you cant make it worse

dazemc · « **Reply #23 on:** July 06, 2020, 01:32:34 AM »

Quote from: bryanj on July 05, 2020, 11:54:45 PM

It happened cos the end cap fell off. Was the screw missing or broken, if missing not toght enough.
Remember the soft alloy washer between the steel bracket and cam cover or you will have an oil leak.
I would reuse all of that, you cant make it worse

I haven't touched the end caps. I should have checked them. Lesson learned, I'm checking the torque on everything now. Going back tomorrow to look for that cap. Thread on the bracket looks fine so it probably did just come loose.

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dazemc · « **Reply #24 on:** July 06, 2020, 01:34:51 AM »

I could have not noticed until I had little to no oil too so despite everything I'm glad. Getting that oil light fixed is going to be a priority now lol

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Author Topic: Rocker arm shaft blew out the side (Read 2703 times)