I noticed that the stock as well as AN Big Sucker banjo bolts are hollow and funnel what I would consider crankcase ventilation into the inner core of the air filter to be ingested into the engine.
Small block Chevy's do the same thing now days it seems.

Has anyone devised a DIY mod to prevent this? I knowon a small block its easy to install a catch can which ensures all oil is captured and not vented into the intake/throttle body, but the hot air is still headed that way.
Seems to me that hot air is not necessarily good for power and combustion and certainly vented oil is not healthy for the intake.

Any thoughts? Ideas?

Thanks,
Jim

 

Found a lot of info via search...imagine that....most in the Touring section. Great pics of mods folks have done to keep oil and hot air out of the throttle body.
The most common recommendation is to fill the oil to the half way point measured when hot as opposed to the full mark. This seems to resolve most peoples venting issues.
I think I will try that first, then continue trying to develop a mod if required.

 

why would anyone run the oil level in an air cooled vtwin lower than the manufacturer recommends? I know people do it but mainly on bikes that puke oil. Even at 1/2 quart low, the crankcase is still venting crankcase gas and oil mist into the intake. Install an aftermarket crank vent to maintain a vacuum in the crankcase which will minimize ventiing and vent the crank vents to the atmosphere. Venting into the intake will contribute to carbon buildup on the pistons over time.

 

Good point. I have an AN BS stage 1 on the Slim amd was looking to build in a catch can set up. Turns out the original banjo bolts which would work for the set up I had in mind, are too short for the AN BS face plate.