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BSA Beagle Rocker Feed

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Although the BSA Beagle 75cc engine looked like a small Triumph Tiger Cub engine, it was notorious in not being provided with a separate oil supply to the rocker boxes. This ultimately led to premature engine failures and the Beagle then being dropped from the BSA line up after just over a year of production.

One solution to the Beagle rocker box problem is to lubricate them by hand before each run out which is obviously less than ideal. I would be interested to know if anyone has implemented a better engineered solution to this problem which then makes the BSA Beagle a more practical bike to own.

I never used mine enough for this to become an issue.

How about a drip feed tapped into the rocker covers fed by a small remote tank under the petrol tank.  They only need  a small amount of oil so it should hardly overfill the sump,
Is there a champhered oil hole on the top of the rocker arms or am I mis-remembering?

If I remember correctly, there are small oval cut outs in the top of the rockers through which an oil mist might have come close to lubricating the rocker spindles. I think your suggestion is definitely one up on taking off the rocker covers off before each ride out and pouring in a bit of oil. However, the positioning of the inlet to each rocker box would have to be carefully chosen as the oil would need to drip on to the holes in the middle of the rockers since that's the only way to get oil on to the spindles. This would seem to mean the inlets being in the rocker covers themselves although the inclination of the front rocker box would be a bit challenging.

Here's a picture of the Beagle exhaust rocker box in which you can see the small hole in the rocker exposing the spindle underneath. The only way of lubricating the spindle as it stands is by dripping oil into this oil which would be very difficult because the spindle is not far off being vertical. Also, you can't flood the inside of the rocker box with oil because there's a relatively large hole down to the crankcase caused by the pushrod tunnel which would drain it very quickly.

Edward Turner's scheme was that oil mist generated in the bottom of the engine by the rotating crankshaft would find its way up the pushrod tunnel and then find its way on to the rocker spindle to lubricate it. I don't think that was ever going to happen!!

Oil mist rocker lubrication was pretty standard on pre war machines. Both my Sloper and Trike run quite happily with mist lubrication via the push rod tubes. However, both of these have open rocker boxes so do not develop positive pressure. Perhaps positive pressure in the rocker boxes can offer a resistance to the oil mist.  Indeed my pal suspected this was a problem with poor oiling opf the rockers on his New Imperial, which were sealed. He fitted a breather to the rocker box and this did improve matters.

Perhaps as an experiment you could run the engine without the rocker covers or with washers between the studs and the rockers to allow breathing and see if it appears the box is getting wetter.


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