Re: RDE-18 powerhead to exhaust plate/gaskets

[chris-p]

The tubes you see at the top of the idle relief chamber are sound restriction tubes. The cavity that the plate covers simply drops down into the exhaust cavity and gearcase. I do not see a reason for them, in fact, they allow moisture up into the powerhead. Probably reason they were removed and the flat plate used eventually. Use the flat plates if you have your motor apart. Drilling holes into the chamber keep it cool I would imagine. I have never had the reason to drill the holes myself.