GS1100g top end on GS1000

[7981GS]

Excellent idea!
I went with the 74mm bore...



.015 off the top of the cylinder and a .005 base gasket also

Daniel

[Nessism]

When I first bought my latest 1000S it had a 76mm piston kit installed (with issues) and some high duration cams (which reduces cranking pressure). Jabbing the starter button resulted in a very unpleasant "crack" noise as the starter clutch complained about the task of turning this beast over.

For you guys "going big", that starter circuit mod suggested by Ray/Pos is worth investigating in order to save your starter clutch, and your wallet.

[srsupertrap]

When I first bought my latest 1000S it had a 76mm piston kit installed (with issues) and some high duration cams (which reduces cranking pressure). Jabbing the starter button resulted in a very unpleasant "crack" noise as the starter clutch complained about the task of turning this beast over.

For you guys "going big", that starter circuit mod suggested by Ray/Pos is worth investigating in order to save your starter clutch, and your wallet.

IMO it's not a matter of even going big, I installed the smallest Wiseco 1085 kit, andrews S1 cams & VM29's and that was enough to induce the starter clutch whack in my GS1000 when the temperature dropped into the 40's. The GS starting system like the charging system is nominal at best, add any additional load and the starting system won't handle it. My half baked solution through the 80's, 90's, 00's on was to install a 16 Amp Harley battery were the airbox resides. This is actually worked pretty good from a brute force solution standpoint but I never liked the idea of the battery weight being placed high up and it still occassionally kicked back when cold. Since 2007 I have incorporated the starter circuit mod from Ray/Pos were I can spin the engine in the Off position and then add ignition by switching to run. I was hoping this would solve the problem once and for all but when it's cold that stock 14A battery does not have enough Omooph to turn it over the engine fast enough to totally eliminate the starter clutch kick back. I swear I have even experienced a starter clutch kick back when jumping the GS from a car battery when the temps were in the 20's.

When I first heard that starter clutch whack I thought I shredded something for sure. I replaced the starter clutch rollers, inspected the teeth (they were Okay) and bolted it back together. That was 1985 and 35K later I am inclined to say it's another inherent design flaw you will have to live with if you go bigger, install bumperer cams and live in colder climates

[mlinder]

I know this has been brought up before, but I can't figure out if I can run a GS1100g barrel & pistons on a GS1000 8-valve. I know the G has a longer stroke (by 2mm, I think), but is the difference in the pistons, rods, cylinder or all three?

I've got a set of GS1100G cylinders sitting here that I'd love to use if I can...

The stroke is determined by one thing, and one thing only: The crank.

It's the distance between the center of the crank pin at TDC and BDC.

Doesn't matter how tall your pistons are, how long the con rods are, the stroke length will be the same, if they are connected to the same crank.

That's not to say that if the pistons were proud of the cylinder deck that you couldn't cut them down to fit, or use shorter con rods, but pistons travel, or stroke length, would remain the same.