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While rebuilding the carbs on my 83 R100RT I opened the air box and saw some flakes in the bottom. I used a vacuum cleaner to remove the flakes and discovered that one valve had rusted completely through the bottom on the left side and mostly through on the rights side.

Beside depositing metal flakes into the airbox, what is the purpose of these valves?

What would happen if I don't replace them and cap the line from the cylinder?

Thanks,

John

jischr wrote:What would happen if I don't replace them and cap the line from the cylinder?

You would be performing the same procedure done by most with this system on their bikes.
You would reduce weight & stuff.

Others will chime in with the proper parts for plugging the hole in the head.
For the holes in the airbox, you can use two of the timing window plugs.


This is one of my heads that was rebuilt by Bob Grauer. He drilled the casting, tapped it to the appropriate size, and installed a nice allen-head plug. Before that I had just cut the tube and flattened the end and folded it over and squashed it tight in a vise. It worked and never rusted through, but it didn't look very good either.

I believe Oilhead sump plugs are the correct size to plug the head holes.

jischr, that is an air injection system that is designed to reduce emissions by allowing a small amount of air into the exhaust so that combustion of gases can continue in the exhaust system. It doesn't make much of a difference in emissions (I've always wondered if its main function might not be to simply dilute the exhaust gases, thereby reducing the ppm count of undesirable gases), but it does add a lot of ugly crap on the bike. Removal is a popular option.

Here ya go, jischr . . .

http://www.webbikeworld.com/Motorcycle- ... pulse-air/

You can also simply put a 5/16 inch ball bearing in the end of the tube that connects to the airbox. Doesn't get rid of any parts, but it stops that system from dumping stuff in the airbox.