1959 Dommi '99'
I brought up this subject earlier. Since then, as advised, I have fitted a 'clean' extension tube to the crankcase breather in order to blow into it. I have found that as I slowly turn the engine over my blowing is first allowed and then restricted. I think this proves the valve on the end of the camshaft is working correctly ?
But, it still blows out oil in more than an acceptable volume. Since the last time I have tightened the head down a further twice. It has a composite head gasket. So far the bike has just done just 50 miles since the rebuild (reground crank, new big ends, mains, re-bore, con rods, pistons, rings, pushrods and oil pump refurb.) The compression is good, as I would expect. So, what do I do now ?
In order to continue running it in, for now at least, I have extended the crankcase breather all the way up to and out along the rear mudguard stay. This will stop the oil flowing back over the underside of the engine and onto the rear tyre. However, will it still function correctly as a breather, or will the breathing be restricted by a build up in the extended breather tube ?
Is there any merit in fitting a breather to the rocker box and so relieving pressure that way ?
Mike
I have routed my breather …
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I have routed my breather (enlarged to 3/8th) to the oil tank ,and fitted a similar pipe down to the chainguard. Check that you have a 3 start pump gearset. NOT 6 start. Too much oil!, If its not fully run in ,you can get blowby.