Rocker Arm oiling issues

As I am just starting to understand this issue, I have started another thread.

Whilst I am undertaking the blue printing work on my 2013 CR, with 2500mls, I uncovered another issue that needs my attention. My exhaust rocker arms are almost seized solid, at least one was, the other almost. This is very concerning

The result of seized and sticking rocker arms is potentiality disastrous - bent valves, bent push rods, damage to piston, or even the bushing just wears completely out and things turn to custard.

The oil way to the rockers is shown graphically in Richard's Manual on Oil Route (see pic below). Oil comes up under pressure through the roller lifters, up through the middle of the pushrod itself, into the screw adjuster that is drilled and has a relief band, now into the rocker arm oil way, into one side of the spindle area where is a circular band in the bushing allows oil to travel across to the exit side of the rocker arm where it exits and lubricates the roller on the top of the valve and residual lubricates the valve spring area. Seems really complicated to me and wrought with potential for starvation down the road if the oil filters and engine oil is not properly maintained.. that one spec of carbon coming loose?

Because the oil way is drilled the same diameter, there is little or no pressure to push the oil sideways to lubricate the rocker spindle. Even the washers at the end of the spindle are a tight fit. In other oil feed systems the exit hole is usually a tad smaller which would provide a little pressure to push the oil along the spindle shaft. Some of the older Brit bikes had wires installed in the oil ways for just this reason. Not really new technology here.

So the fix is to provide (hand cut with dremel) a sprial oil way along the bushing to allow oil to migrate from the centre band to the other areas of the shaft. The problem is also the shaft does not move very much - it does all its work within a few degrees of rotation. I may also peen the oil exit hole slighty to provide a little pressure - not sure how I can do that accurately.. still thinking on it.

I will post photos of the progress. Will not be able to test the fix for a few month yet though.

It is definitely something that should be looked at when you check your valves. Norton should be instructing their techs to do this as routine, or there should be a service note and a warranty fix. And I don't expect Norton to make any insight or comment here or even acknowledge this issue, or provide any help.

Again, I am glad I am investigating every little thing in my engine. 2500miles only on mine, losing count of the hours of time taken so far.

That’s a good ‘investigation in progress’ Bushman.

It doesn’t seem like you’ve nailed a root cause just yet though. You’ve found lots of ‘points to imrpove’ for sure, but it doesn’t seem like you’ve yet conclusively established the cause of the seizure.

Rocker shafts don’t usually need copious amounts of oil, so whilst I’d fully agree with your analysis that the oiling would be better if it encouraged a small build up of pressure in the shaft, I can’t see that being your root cause. If it was, would all fail in a similar fashion?

Could your oil gallery have been blocked somehow perhaps? But here, your conclusion that the oil ways are over complex and a weakness due to possible blockages is understandable when compared to an old Norton, but in modern engines, there are many long and small galleries, which are not generally seem as a big potential failure mode.

I think you got your ‘sticking some wire in the rockers shaft’ story the wrong way around BTW, my understanding here is that that was done to reduce oil flow to the head in general, as a fix to over full rocker boxes causing oil to be sucked down the guides and burnt.

One question on my mind is your oil choice (I’m gonna start a separate thread on this question BTW). Obviously the cylinder head on and air cooled engine gets bloody hot. Could your oil be breaking down? I’m not sure where you’re at, do you ride in particularly hot climes?

I hope you don’t think I’m nit-picking here or anything like that, im just following your thread with great interest and am keen (as I’m sure you are) to really understand the actual specific root cause of your seized rockers.

He's a White Rock boy, just down the road from me here in Langley. ( Vancouver, BC area)
Very moderate climate, slightly warmer than Manchester UK in winter, similar summer temps.

Glen

Last oil change Amsoil 10-40 full synthetic motorcycle oil, filter change.
Had a full 400 mile day back in June - with a good chunk of it 75 to 85mph - others in the group were riding 10mph faster and the Norton really did not feel it wanted to keep up, so I fell back. I am a fairly spirited rider and usually give it a good whatfer when I am out, nothing I wouldn't do on my 71 750 Commando.

I have had comments about the rocker spindles are not properly hardened and/or the bushing material could be improved. I am looking into replacing the bushes with better material. My spindles don't appear to have any marks or wear.

I will be looking for any oil blockages, as I have the motor fully apart I will take careful note to make sure everything is clear and then properly primed for startup.

worntorn said:

He's a White Rock boy, just down the road from me here in Langley. ( Vancouver, BC)
Very moderate climate, slightly warmer than Manchester UK in winter, similar summer temps.

Glen

Click to expand...

In Brookswood Langley - we're Neighbours...

There you go, my sources are a bit off once again...

Glen