Suzuki 2 Strokes

So there’s a material that covers the underside of my cylinder head shrouds that looks like roofing tar. Unlike roofing tar it’s quite hard, though I imagine the heat cycling has caused it to harden. If I had to guess it was added to quiet things down, but it seems to me it would inhibit cooling. Anyone ever see this done to a shroud? It was on the inside of the points cover too!

Chris

The covers on my GT550 cafe build had the “tar” on the underside as shown in the pic. Had the tar removed before spiffing up the covers.

GT550-ram-air-0777 by jabcb, on Flickr

The GT550 points cover is an aluminum casting similar to the other covers. No “tar” on the underside on all of the ones I’ve seen.
The GT750 points cover is a steel stamping with a “tar” disk on the back side.

Yup, that’s exactly what I have! Guess I’ll just leave it in place since apparently it’s common. Maybe the former owner replaced the points cover with one from a GT750, hence the “tar”.
Thanks for your reply jabcb!

It's been on all my 550s including the one on the 550J I bought in August 1972. Cowl & points.

It'll be just a sound-deadening material to stop that big thin alloy casting ringing.

Yes, to quiet down the ringing. All of the 380 covers I've seen have it.

Any potential ringing on a GT550 can be solved with the expansion chambers.

That doesn't solve it - you just can't hear it!!!