The Air Inlet Seal Problem

Bob Axsom · #1 09-26-2005, 05:48 AM

I looked at the photo posted by Paul Dye and have a suspected cause of the problem but was unable to post a reply there - new experience. A good test would be to light the area well and video the start, run and shutdown sequence. The air inlet is good distance from the center of rotation/thrust line of the crankshaft and there is the long forward arm from the vertical center of the engine air inlet to the location of the airbox inlet. All unit motion of the engine is magnified at the air inlet seal because of the two arms, vertical and horizontal. There are large rotary displacements of the engine around the crankshaft center line at startup and shutdown which cause really big side to side motions of the airbox while the cowl air inlet is rock solid. I suspect the problem could be solved by replacing the seal rubber with the relief split at the bottom rather than the side. A longer seal would not hurt either if will fit.

Bob Axsom

Ironflight · #2 09-26-2005, 06:44 AM

That's exactly my first plan to try this morning Bob - going to put on a longer seal and put the slit in a different place. I was goign to make a video of it from the front, but if I can fix it empirically, I'm not sure I want to actually know how much it moves!

Paul

R.P.Ping · #3 09-26-2005, 11:49 AM

Also....Try it without the relief split. I don't have one in mine and I don't need it...works just fine.

Bob Axsom · #4 09-26-2005, 12:25 PM

How do you take a flat piece of reinforced rubber and wrap it around an opening and have no ends (relief split if you want to call it that)? I have thought about it and it seems like you could use "patch" of the same material RTV it onto the primary sleeve then sew the end edges to secure it. I'm thinking that's not a bad idea. Is that something like what you did?

Bob Axsom

R.P.Ping · #5 09-26-2005, 06:22 PM

I have one piece that raps around the bottom and one piece across the top.
The ends of the top piece are bent up 90 degrees and the piece on the bottom overlaps the top piece on each side. There are no relief cuts to allow the cowl/scoop to move into place. It flexes enough without relief cuts. In fact I have no rivets on the bottom piece, just fuel tank sealant.
I think I remember the instructions saying to make relief cuts to allow the cowl to be put on and taken off. That's why I say I don?t have any. Sorry for the miss leading info.