Missing spring

I recently installed t he new design of tacho drive seal which now cotains a small spring. The tacho drive started spewing oil again. Removed the tacho drive and the spring is missing. It must have fallen into the engine? No damage to tacho drive, no metal bits when I drained the oil. What do I do - keep riding it or investigate further?

You ought to address your excessive crankcase pressure issue with a one-way reed valve.

So glad I'm not in your boots. Try inserting a flexible magnetically tipped search tool for fallen bits into those tach-drive impossible to reach areas ? Maybe the spring is resting in a nook or cranny closeby. Failing that you could pull the oil drain plug and try there with the magnetic probe. Failing that you are left with pulling the head and barrels to search with good lights and the same search-probe. I'd pull my hair out at first then re-think the search but I would not leave the little spring in there. There is a better rawhide seal fix that worked perfect on mine listed here somewhere on the Forum. The aluminum tach drive is bored out a bit to press the seal into place. Yes fit a reed breather too. Good Luck.