crankcase breather and altenator question

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Jul 10, 2007
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1. I am just beginning my '71 rebuild. Is there a better way to vent the crankcase than the stock timed breather off the camshaft. I have not seen any posts dealing with pre '72 commandos on this.
2. I have a Mk3 single phase 180w altenator. Can I run a 55/60 halogen headlight with this altenator.
1. Go for the 74 onwards setup, drill 2 3/8 holes in the timing side crankcase into the crank chamber to allow the air out, and then insert a steel tube in the back of the old magneto position to take it out of the engine, route a flexible tube to the rear of the bike or if brave into the air cleaner. Engine needs to be dissasembled to do this mod :lol:

2. Yes, I do with no issues but I do not ride around town.
There's info on a breather upgrade here which would still be suitable for a '71 model (the 72-73 crankcase modification doesn't apply):

I don't think you should have any problems running a 55/60W headlamp.
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