[Frank]

Hi All,

The upper case has something called a Breather Plate with a tube coming from it (think case upside down on bench). There's a tube with a short rubber i.e. flexible tube on the end that inserts somewhere into the lower case. Does anyone know what this is for? I always thought the cases were vented through a simple hole from the top but this looks more complicated. I would think if the tube is an inlet of some type, that it wouldn't/couldn't vent very well due to oil in the lower case blocking the entrance. Thoughts or insight? It's part 16165 in the pic.

 

[SparkyMJ]

I think it's just the hose routing internally that leads up to the actual hole on the lower crankcase. The volume of the crankcase under the pistons is what changes, so that internal tubing leads to the hole where the external tubing hooks up to your airbox, so that the crankcase fumes can be sucked in to the intake and burned off.

It's the same on just about every bike, just plumbed a bit differently on others. Crankcase vent lines also tend to get dirty and carbon-y in my experience, as do the PAIR valve plates. Worth a good cleaning once in a ever. Hope this helps.

-Mike