Exhaust interchangeability?

[pasteurized]

Just wondering... will exhaust from a 1980 GS750 work on a 77 GS750? They look the same but I want to know for sure before I go purchasing.

Thanks!

[pasteurized]

anyone know? I am thinking about making a purchase very soon and wanted some input. As long as the Exhaust port size on my bike and the exhaust I am looking at are the same, I can make it work.

[isaac]

In case it helps: I just measured my 82 750's 16 valve exhaust, and the exterior diameter of the unflared header pipe at the head is 1.85" (circumference 5.8") and the bolt spacing (measured from the head centers) is right on 2.75". The spacing between runners (measured from the centers at the downturning kink) is just over 3.75" for the outers and just over 4.75" for the inner two. If those match, you should be in business.

[pasteurized]

Thank you VERY much isaac. If anyone else is wondering, it seems that the 16v 750 exhaust is bigger than the 8v 750. From what I can measure, mine is 1.2" in diameter (30mm), and has a circumference of roughly 4 8/10" (give or take a tenth).

So in other words 77-79 and 80-up exhausts are not interchangeable.

[isaac]

You're welcome on the size checking. Well, as I figure it, they still might be technically interchangeable. Have you checked the bolt spacing for the individual runners, and the runner spacing itself? Those might still all line up. If so, then you'd simply have a slightly less tuned exhaust that has better anti-reversion characteristics due to the smaller port exit compared to the runner diameter. I'd check those other numbers to see what happens.