Back to my V502. I have had continuing problems with engine oil leaks for some time. Worst after high speed cruising. Saw previous post re breather unit and have some seepage here despite replacing the air filter and cleaning and checking the assembly. Ball thingy seems free. main area of leakage is the union of the tacho in the timing chain cover. I have been told this should not leak as there should be no oil as such in this area and certainly no pressure. I have carried out a leak down test and found one side below standard. Air heard in the crank case through the filler tube. having had the heads rebuilt and rings and guides replaced by a reputable team less than 12 months ago I have stripped the head of the offending side again, replaced the rings again this time myself despite the gaps within limits, lapped the valves in again ( one appeared bent and certainly not seating well) and this improved the leak down test. However I still have a seepage from these two main areas including the tacho union. My brass tacho union is very worn and seized and has resisted removal to date. Has anyone else experienced leaks such as this or have any further suggestions.
Mine can be leaky but not from there. Certainly I never fill the oil beyond the half way point on the dip stick as any more will always find its way out. As a point of interest how many miles has the bike done?
The bike has done around 35-40k I think. I have had it for nearly 30 years and when I was 22 ish  (28 years ago) I put new pistons and barrels in it before touring Europe with my mate on the back. Pretty much an engine rebuild. I still think of the pistons and barrels as relatively new as they have only dome around 10K since. On recent inspection they are looking fine. Â
I’m guessing the tacho cable union should have like a rubber boot for the timing cover end to keep the weather out, on mine the sealing of this wasn’t good enough (to keep out the water) so I augmented it by wrapping insulation tape around the top end of the boot and the cable sleeve, in turn secured by a small cable tie. (To prevent it coming undone.)
Best plan is to clean the engine with de geaser and then cover in talcum powder.
Start with tank of (fuel in carbs should run for few mins) and watch for oil to stain the talcum powder
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That should pinpoint the source of your leak.
Oil leaks can come from rocker box gaskets, loose or split breather hoses, o-ring failure are the barrel to block joint, loose or damaged oil pressure sender or boss