need help...GS1100 engine parts interchangability

[maroon81GS]

My 81 GS1100EX has a 78GS1000 motor in it and I'd like to build a 16 valve motor to re-install into the 81 GS1100EX frame....not real hot....just kinda stock. I've acquired all of the top-end parts for a 16-valve motor, including various 16-valve heads, cams, valve covers, etc... for 1980-1983 years. Can anyone tell me what lower end parts are equivalent and can be used with the 16-valve heads. Are the engine cases, transmissions, crank, rods, pistons, and cyliners from any 1980-1983 GS1100 chain-drive model the same as all of the other chain-drive 1100 models from those years? I'm trying to determine what lower end parts I need to get to go with my 16-valve heads. (I do realize the difference in valve cover bolt pattern for the 80-81 16-valve heads vs. the 82-83 heads, but this doesn't impact the ability to bolt a head to the cylinder ^ case. Also, are the cams different between the 80-81 and 82-83 16-valve GS1100E motors (more aggressive profile?), and if so, can 1982-83 cams be used in 1980-81 16-valve heads. I just want to put together a good solid 16-valve motor for this bike and I'm not sure what parts I can use. I've searched the different sections of the Forum and can't seem to find the answer. Great site.......keep up the great dialog. You guys have been a super resource. By the way, I did purchase the "Suzuki Parts Cross-reference Software" from Zedder, but the 81 GS1100E is not included in the listed models. thanks

[chef1366]

All 80-83 1100 sixteen valve motors will work. You can even use the 1150 but the cranks are different. The piston rods are 20mm and the 1100s are 18mm.

[posplayr]

Also, are the cams different between the 80-81 and 82-83 16-valve GS1100E motors (more aggressive profile?), and if so, can 1982-83 cams be used in 1980-81 16-valve heads.

I'm pretty sure I collected up all this info correctly....

The 80,81 and 82 GS1100E's all had the same cams. I remember reading that there was a quality control change that improved the head breathing due to more precise valve job in 82. Before that there was greater variation bike to bike; so the 82 is a little faster. The 83 had the hottest cams more lift on both intake and exhaust.

Below is an output of a spreadsheet I put together to decide on what cam to put back into my GS1100ED. Based on several expert opinions I'm going with the WebCams 0.340's with APE HD springs (thanks Bill,Ray,Kris) \\/.

Good Luck
Posplayr

Go here for Cam specs summary.

http://www.thegsresources.com/_forum...d.php?t=140749

[maroon81GS]

Hey, Chef1366 and posplayr....thanks for the feedback. This helps. One more question that's not clear to me. Are all of the lower end parts (cases, crank, transmission) as well as rods, pistons and cylinder from a 1980-1983 chain drive 8-valve motor exactly the same as those used in the 16-valve motors? If so, that makes building a motor from parts alot easier. Also, by chance can a 16-valve head, cylinder, and pistons be connected up to a 1978-79 GS1000 bottom end or don't these match each other? Thanks again.

[chef1366]

They have different bottom ends and cranks. The pistons are made for four valves and not two. I think the 1100 cylinders are the same for the eight and sixteen valve.