4V Spark plug tubes in rocker covers

Hi folks,

My first entry into this most helpful forum is a 4 valve rocker cover question —on my 2012 registration Sport 1200 4V, as it happens— but the design is the same, yes?

Checking the tappets the other day (for the first time since I got the bike a few months ago) I removed each rocker cover to find that the metal spark plug tube came out as well —attached to the rocker cover. I thought, hmmm... didn't expect that . . . but OK.

Looking at the parts book, and this website later, it seems that the spark plug tubes sit inside the recess in the head casting and can be lifted out separately on their own.

So my question is: do any of you know if this is a later mod made by Mandello? Or is it a cunning mod made by the previous owner? Guarding against oil leaking into the plug recess, perhaps? Or have the tubes seized so firmly into the rocker cover casting that I thought they were actually made that way?

Cheers,
Riversider (in Scotland)

No, the tubes are a separate item sealed top and bottom with o-rings. I'll post pics in a bit.

Rocker cover o-ring.

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O-ring in head.

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Pete

Ugh! Picture #2 has been a problem on my bike. The left side has always leaked a bit and I am on my fourth o-ring in there. The factory changed that design and for good reason.

The o-ring is still there in the later bikes. It just doesn't get disturbed by removing the rocker cover. The 'Tube' is truncated and only goes between the head and the rocker support.

Pete

Yes —what Pete describes is what I realised (after refitting) was the proper factory relationship between the rocker head and the tube. The tube in my bike, however, was so very firmly attached to the rocker cover, that I thought it might be a later design, or a cunning mod by the previous owner. Does this ring a bell with anyone? Might it be an advantage against oil seepage?

On the other hand —it could just be seized! And next time I do the valves I'll give it a shot of Plusgas and a good twist.

If it isn't leaking? Don't disturb it. It doesn't matter if it comes off with the cover or stays in the head.

Sure thing, Pete, and it is already left as found. But I was interested to know if it was some sort of mod that people knew about.

Riversider