Photos of piston and valve with stock crank vent system.
#11
#12
#15
The biggest issue I have with it is that it robs power and fuel economy over time. It would be easy to decarbon the pistons on occasion using BG 44K or Seafoam through the intake. I don't want to hassle with it. A catch can is impractical because it would have to be a small one and would likely need emptied too frequently for my taste. Venting to the atmosphere is fine so long as it's routed such that oil mist isn't dirtying up the back of the bike or getting on the rear tire.
#16
So I have been experiencing some oil puking out of my M8 114 air cleaner. So I know some of that is ending up in the combustion chamber. Here are some photos of a piston and a valve. The pistons actually look almost identical so I only included one. On the valve photo there is not much gunk built up on the valve. But notice the oil above the valve seat.
looked at mine with 8000 Nothing but am going to vent to atmosphere .
#17
Not sure what the OP is using, but I'm using Syn3. Oil type is not a factor in this issue, and all of them (M8s) have to be doing the same thing. It's just a poor design that carried over from the the twinkies.
#19
The biggest issue I have with it is that it robs power and fuel economy over time. It would be easy to decarbon the pistons on occasion using BG 44K or Seafoam through the intake. I don't want to hassle with it. A catch can is impractical because it would have to be a small one and would likely need emptied too frequently for my taste. Venting to the atmosphere is fine so long as it's routed such that oil mist isn't dirtying up the back of the bike or getting on the rear tire.
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strych9 (08-20-2018)
#20
Every motorcycle built in the last 30 years or so will have a similar setup. The difference is the air box, Harley is still using the exposed open air intakes, most other manufacturers have switched to an enclosed air boxes with separate filters designed to control the oil from the breather (even then oil still makes it to the intake).