Rocker oil feed

Alright Neil, when turning my Mk3 engine minus cylinder headover by hand oil pumps out of the rocker feed pipe. Don't know the actual flow rate but it is sufficient to make a mess on the rest of the engine unless the end is temporary capped or wrapped in cloth, hope this helps,

Simon.

The scavenge side of the oil pump has a larger capacity than the feed side, so air bubbles will always be visible in the return flow. This is normal, so don't worry about it.

As for the rocker feed oil flow, how long do you let the engine run before you kill it again? Depending on how long the engine has been standing it could take a while for oil to arrive at the top. But this is pure speculation, since I haven't tested or observed it on my own 1972 Commando Roadster.

I RECENTLY HAD NO OIL PRESSURE FEEDING ROCKERS,SO I REMOVED LOWER BANJO OIL FEED, AND USING OIL CAN PUMPED OIL BACK THROUGH CASING TO OIL PUMP,THIS PRESSURISED OIL PUMP,AND THEN STARTED BIKE WITH PIPE OFF ,THEN OIL CAME OUT WITH FULL PRESSURE.I WOULD RECOMEND PUTTING OIL THROUGH ROCKER SHAFTS FIRST IF NO OIL HAS BEEN FEEDING VALVES ETC

You've been informed correctly that the oil filter is fittedon the return from junction block to filter and filter to tank, and yes the flow is straight from the tank to junction block. Importantly this means whilst you've had no or limitedflow to the rockers theres been no or limitedflow to the big ends too. The filter would create resistance to oil flow, hopefully the pump has been able to suck enough oil through the filter to provide adequate lubrication to the big ends.I think an engine strip to check the big ends is required, for peace of mind at least.

Simon.

Previously wrote:

I feel sick to the pit of my stomach because I've just started the engine and, although feed to the rockers is now good and the return is normal, the engine smokes especially from the left cylinder and I can hear the plugs fouling the longer I run the motor. I have been rebuilding my Commando on-and-off since 1985 (yep, nineteen eighty five) and now it looks like I've caused some serious damage by making an elementary mistake. I'm hoping premature wear will be confined to the valve guides and not the cylinder bores or worse, the big ends. I suppose I have to be thankful the engine didn't seize and do some catastrophic damage. If anyone can tell me how the engine managed several hundred miles like this please explain. I'm sure we'd all like to know?

Hi Neil,

I sympathize with you on this one. I guess its no great comfort to you, but I did exactly the same on rebuilding my Matchless G80 ten years ago. Despite having studied drawings and diagrams I managed to connect the oil lines the wrong way around! After the first 5 miles the piston nipped up and scored the cylinder. Mind you this was a standard bore cylinder with a standard n.o.s. wirewound piston, that I had gone to great lengths to source. Of course a rebore and new piston was needed, but the bigend and crankshaft bearings survived, 15.000 miles later they are still good and running fine. They probably survived because I flooded the bottom end and rocker box with oil before starting up, but also because ball bearings with their relative smaller area of metal to metal contact are less sensitive to oil shortage. What I'm trying to say is that your worst case scenario could be "just" a rebore and new guides, but a strip down of the topend must be done to asses damage. I'm still at a loss to explain your several hundred miles of initial running in! Good luck and lets hear how it goes!