Pistons larger than 75mm are going to be tough to find second hand. I looked for over 6 months before acquiring 2 pistons from different sources. I was talking to Ken (werase643) the other night and he mentioned something about stock pistons from another bike that should fit, a specific year Kawasaki I believe. Boring a stock 74mm cylinder 5mm over will cost about $50-70/hole. Piston to cylinder clearance is about .002 from what I remember.

Megacycle (//www.megacyclecams.com) will modify stock cams for $266. See page 50 in there catalog for lift options. They also sell the heavier valve springs.

Necking valves can be done by most anyone with a lathe. Reduces the cross-sectional area in the ports allowing for more flow. Plus reduces the weight of the valve, less valve float.
In the pic: stock intake (left), necked intake (center), necked exhaust (right).
http://img.photobucket.com/albums/v64/dgyver/GS500/GSneckedvalves01.jpg

Excessive porting can have adverse effects. On the intake, just clean up the casting marks and the mating surfaces at the carb boots. The rough texture helps with the atomization of the gas. The exhaust could use some porting and polishing.

I do not know the max that can be safely removed from the head yet. But if the cylinder is milled be careful about taking too much as the piston could hit the head. In this pic you can see the imprint of the piston size in the squish area of the left. http://img.photobucket.com/albums/v64/dgyver/GS500/GSstockhead02.jpg

If you really are not concerned about reliability....knock out the sleeves, bore and Nikasil the cylinders then install some 85mm pistons.

well if you want to get really retarded.
http://www.sportrider.com/bikes/146_0110_gs500/

hahah for the same price it would cost to build a CSXR GS650, I could get an SV650s..  

I was lookin' around, saw a ZR 7s..  anyone have any idea about this bike??  just found a good deal on it, was thinkin' how it would fair up w/ the other sport bikes....

Ok everyone, question

IF I get the 2001 GS500 engine, carburator, airbox, wiring harness, and I Guess the Throttle cable as well, what else would I need to complete the swap into a '98 model bike??  

I'm guessing this would be better than just fixing the current problem, and probably cheaper/easier too.  And the new engine has an oil cooler right??  

Maybe later on, I could get one of James G's 2001 gastank retro fit into the 1998 model=)..  so what u guys think??

Quote from: TeBoOk everyone, question

IF I get the 2001 GS500 engine, carburator, airbox, wiring harness, and I Guess the Throttle cable as well, what else would I need to complete the swap into a '98 model bike??  

I'm guessing this would be better than just fixing the current problem, and probably cheaper/easier too.  And the new engine has an oil cooler right??  

Maybe later on, I could get one of James G's 2001 gastank retro fit into the 1998 model=)..  so what u guys think??

personally I would use my old carb, wiring harness, etc. etc.  only use like the block, head, stator, ign pickups.. everything else use your old stuff.. cause the carbs are different on the 01's so you'd need a new throttle

No oil cooler on the '01 ... only the '04+.

What else do you need?  Tools for disassembly/reassembly, a floor jack or some other way to muscle the engines out and in, a buddy or two at just the right time(s), and a bunch of patience.

Oh, and a step-by-step "How To" like the list richard got from someone on this board.

Hey if I buy these, would I be able to run the stock '01 Carbs? ? ?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4515989953&category=35597

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4515990417&category=35597

I know kerry said I'd need the stuff for the throttle cable, and all the stuff mounted to it.  And also that I'd need the choke lever, etc. . .  So could this possibly work??  I'm hoping to pick up the motor once paycheck hits....

BTW...   diBS! ! ! !   (that kinda thing seems to go well around here I guess :dunno: )

yep, you can use either style carbs with those, and if you read the first post of the ebay user id list thread you'll know all about the "dibs" thing.

I never really got what "dibs" meant...  It just seems like if someone wants something on ebay, they say it...

Nice find.  Good luck on the auctions.  

anyone know the size of the bolts that keep the gas tank on??  (the ones under the tank when u take off the seat and battery right??

On the pre-'01 models they have the same head size and threads as the bolts that hold the passenger grab bar on.  But the tank bolts are about half an inch longer.

They are M8x1.25 but not sure of the length.

I thought I had answered this question before!

In the photo below, the bolt on the left is from the passenger grab bar.  The one on the right is from a fuel tank mount.  The ruler is marked in centimeters.