Pinning down the rocker shafts - what's it all about? In short the rocker shafts in a SR500 cylinder head should be an interference fit, making sure that the rockerpads are nicely parallel to the camshaft axis. When they start to spin, initially nothing much happens until the rocker shafts wear out the bore allowing the rockers to move up and down in the bore at which point the wear rate accelerates and rather soon than later, you end up with egg-shaped holes and rocker pads which do not wear evenly in the center but on one side. In the process of which this will not only lead to premature wear on the rockers, but also on the camshaft. Most notable because it sounds like some angry troll is swinging a really big hammer in the top-end of the engine. The fix is pretty simple: four M6x10 grub-screws, a few minutes on a drill press and some loctite.
Leading up to this point, a few more things had to be tackled. First of all, was to polish the valve covers. Yep, you read that right, a pure job of vanity. Remove the flaking, yellowed clear lacquer and then go to town with ascending finer grades of emery and then buff living daylight out of them. Technical value of this mod: -1, i.e. completely pointless and I don't like freshly polished stuff. But scratched, weathered aluminium? Hell yeah, one really, really dirty secret of mine.
Way more useful and completely unseen: a knurled nut as a petrol tank hold
down. So at this point I can strip the whole bike off its seat and tank
without a single tool. If you're messing about with one of these as much as I
do, it's a real timesaver.
For example, when you have to take off the rockerbox.
Which can be done, without taken the engine out all the way, tilting it is actually sufficient.
Even though these are brand-new rockers, it's obvious, that the wear patch is nicely centred and very even on both. (Also a reliable indicator for good lubrication at the first startup.) The four bosses that are visible in this early 2J4 rockerbox are actually the spots where the later 48T-model will have bolts to lock the rocker-shafts in position and thus prevent them from spinning. In theory this will lead to more wear on the shafts, but with none (or next to none) on the heads this is a way better solution. Positioning might be critical, but the more I think about it, the more I am pretty sure, one could pull this one off on a 2J4 cover as well...
The actual modification can be carried out with drill-press and probably, if you're confident even with a handheld drill. I did it on the mill, because that's what I have.
The upper "ears" of the head-mount obviously have to drilled out to 6mm afterwards or tapping would require a very long M6 tap.
The finished article. Loctite and lock-nuts is a bit of an overkill, but I think considering the extra-weight of the sidecar, those two M6 nuts should be bearable.
As a gentleman in general is not meant to motor after dark, it took me a while to find out that: the illumination in my tach had failed, I really want LED bulbs in both speed and tach (to save a few extra Watts for charging the battery) and the sidecar position light is super bright and blinding me - again fixed by installing a LED bulb.
It says a lot, if you can notice the blinding of the position light in bright daylight...
And lastly - it's not a bodge job, if it works. Now all three contacts are soldered onto the LED cob, because the socket in this (admittedly) cheap Guzzi V7 sport tail-light is single-handedly the worst I have ever had on any bike.
What next? Guess a few lovely Autumn ride outs won't do harm...
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