t20 tiger cub breathing

I have just finished recommissioning a 63 T20. The weather has been such crap that I have not had the chance to ride it yet but it starts and sounds good. I does seem to be passing some oil out of the engine into the primary. I am wondering what is used to vent the crankcase on these bikes. Can anyone explain the breathing system? I am not even sure if the breathing is intended to be through the primary like many older bikes (e.g. velo mac) or if there is another form of breathing.

Thanks in advance for any input.

I can’t recall the standard breather arrangement. But I do know that when I built one as a yoof, managed to build it with NO engine breathing facility at all !

I realised after several attempts at sealing various leak, with yet more silicone, that sumthin wasn’t right !

I put a big open breather from the old distributor drive plug, looked kinda RE Continental GT to my youthful eye and it did work instantly currying about 50 leaks !

Yours is a ‘63 so doesn’t have a distributor I assume, so this option would be open to you as well if you can’t figure out the original method.

The C15 is based on the T20, the C15 breathes through holes in the camshaft and camshaft bushes into the outer timing cover and then out into free air through all the unbushed shaft, clutch cable holes and a notch in the cover at the back.

kommando said:

The C15 is based on the T20, the C15 breathes through holes in the camshaft and camshaft bushes into the outer timing cover and then out into free air through all the unbushed shaft, clutch cable holes and a notch in the cover at the back.

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I must have screwed up the camshaft bush then I guess, either by fitting a bush with no hole, or not lining it up.

This is a Tiger Cub camshaft, the hole in the journal is the breathing hole, its a timed breather so its open when it passes the hole in the outer camshaft bush.

I like Cubs, still got the one my Dad bought in a (partially successful) attempt to keep me off the streets and out of trouble when I was 12.

But at a tad over 6ft and 14.5st they’re not really viable. And even if the engine was, the brake aren’t !

Was kinda hoping one of my daughters might be interested, but it transpires they have their Mums gene… and could not be less interested in anything motorcycle related !