Hi, Dennis.
Not knowing the gasket thickness, I’m not sure what, if any difference this modification would do.
The 26 is a powerful and reliable engine as is.
In my opinion, it is the best of the Surpass series.
Between the 20 and 26, I have around seven or eight of these little gems and aside from a few custom venturis, they are completely stock - never had one apart.
However, it might be an interesting experiment to try.
If you have a Surpass 26, generate some data on the stock version and then install a thinner head gasket, readjust the tappet clearance and reevaluate the performance data.
For what it’s worth, I have a triple engine plane powered by three Surpass 26s. I set it up so that the outboard engine quits first, then the inboard and finally the middle.
The plane weighs just over 90 ounces and will actually fly on just the one engine.
Still though, my favorite small four-cycle engine is the Saito 30. Actually one of my favorites of all my engines.
Bob Z.