Quote Originally Posted by jiott View Post
The Zipper kit was mentioned; I am curious, does anyone know what the compression ratio becomes with the Zipper kit on a 912ul and on a 912uls? The Zipper kit increases the bore but not the stroke, right?
The Zipper (1484cc) replaces the Pistons and cylinders, increasing the bore only. The bottom end of the engine is not touched.

There are high (11:1) compression and low (9.7:1) compression kits available. The low compression kit allows the continued use of 87 octane fuel to make about 105 hp, where the high compression requires 92 octane, and a hd starter and slipper clutch in the gearbox are recommended, which will produce about 115 hp.

There is also a 1622cc kit which requires some machine work and change of the cam to achieve 125 hp.