'83 brake proportioning valve

[dan filipi]

I have the proportioning valve out and was wondering if there's any service to be done on it.
It's a solid block of aluminum that can't be disassembled and when I blow through it it seems like there's an equal resistance so I'm assuming it's pretty much open or it's plugged but I thought someone else might have been here before.

 

[scdmarx]

I hadn't thought about it before, but I guess our linked brakes would need some sort of metering device. Most cars have a combination valve. On a car, the proportinging valves purpose would be to allow less pressure to the rear than the front. The front needs more force because of the added weight. I suppose on a motorcycle most of that weight would come from centrifical force."?" The metering valve part of it would allow pressure applied to the rear first untill the psi threshold is reached, then allow pressure to the front. This creates a drag at the rear wheel, causing the vehicle to remain straight - like feathers on an arrow.
If it's non-takeapartable, then the only thing you'll be able to do with it is flush it to clean it out. It probably just contains plunger, spring, oriface. Not much to go wrong with it. Try to keep the contaminated brake fluid with funky hose material cleaned out.