OutlawGPz wrote:
Besides the carbs are there any major differences between the 81 GPz engine and the 82 and later engines? I found a big bore kit for the 82+ GPz engine to punch it out to 615 cc and was wondering if it would work in my 81s engine. If so..i see a full tear down in my future lol...
The head and cylinder block are different castings.
The head gasket, however, is the same.
Same comp ratio.
Same bore.
Same stroke.
Pistons and wristpins are the same.
Crank and secondary-shaft parts are the same.
Con rods and bearings are the same. (There appears to be a typo on the '82 fiche parts list for a bearing.)
Transmission parts are the same.
The head has larger intake ports on the 82/83 for the larger carbs. Carb center spacing is the same.
The valves and valve parts are the same.
The cams are the same but 81 has a tach drive cut into the exhaust cam. (Intake and exhaust have same profiles.)
82/83 has no mechanical tach drive.
Valve cover gasket is different.
Cam chain tensioner is different.
As to why a 615 kit for an 82/83 wouldn't work on an 81... this is a wild guess... perhaps the liners on the 81 cylinders are thinner and can't be bored out as much?
Post edited by: loudhvx, at: 2007/10/22 03:01