Q: Secondary Air Injection

[beatpusher]

Doing maintenance during the cold icey months up here and i decided to do the SAI removal. It was plugged off during my dyno tune so why have the extra hardware and hoses all over the place right?!

Anyways, I know I can buy block off plates from one of the board members here (which I totally appreciate) but once I removed the stock pieces from my bike I realized the parts are just a low grade plastic. I have access to a rapid prototype machine and think it would be cool to model my own, question is, how much pressure is there exactly under theses covers? Is aluminum necessary? I know heat is a possible issue. I did notice the stock stuff is barely even torqued down, so I'm assuming that the covers aren't 'holding in' a lot of pressure...right???

Any comments welcome!

[Martin_R]

The little pressure that makes it to the SAI ports is taken care of by the reed valve + valve bracket (rubber covered metal piece under plastic piece).

All the plastic has to do is to hold the metal reed valve bracket down.

[beatpusher]

Thanks for the reply. The reed valve is removed during the process so that's the concern I had. I'm getting the piece mocked up right now for fitment, maybe I'll just fire the motor up and see if anything flies off!

[superduty]

There should be no positive pressure under the reed covers. The SAI works by a vacuum created by the exhaust gases leaving the head. In theory you should be able to run the engine w/o the covers attached but you'd run the risk of sucking undesirable into the exhaust system.

[Martin_R]

Originally Posted by beatpusher

Thanks for the reply. The reed valve is removed during the process so that's the concern I had.

You do not necessarily have to remove the bracket from under the blockoff plate. I left mine be. The rubber covered bracket is a very good gasket, so you do not need to fashion your own.