1980 Z500 powerup - cylinder swap?

Hi guys,

I'm chasing more power (hmm, something new...) from my Z500, and I'm thinking of swapping cylinders and head to something larger (750, 1000, 1100?)

Anyone done this, or know if this is possible?

I have a spare motor to tinker with, but want a bit of assurance before I cut in. I think I can just enlarge the holes in the engine cases and drop Z900 cylinders on, but will the bore centres of the 900 line up with those of the 500? This is the big question. Anyone have the two cylinders they can compare for me?

Or will a 750 900 or 1000 motor fit into the frame? I'm happy to fabricate mounts etc., just an issue of the respective sizes.

Thanks all,

Steve

im at a complete loss on this one!:ohmy:

the biggest stock cylinder block that you can use would be a 550 block. anything bigger has wider cylinder spacing(even a 650 is too wide). if you get a 550 block, you can bore that to the wiseco 615 kit. anything bigger than that would be very expensive, and completely custom designed.
as to a completely different (and bigger) motor, it can probably be done, there have been 1000 and 1100 motors in 650/750 frames. as long as it can physically fit, just fab up the custom motor mounts. and while you're at it, brace and gusset the frame extensively as it will be seriously over stressed.
another thing to look at is how you will be getting all this new power to the pavement. you should probably look at upgrading the rear end to get the most out of the bike. the stock swingarm is probably going to flex a lot as it was only designed to take abuse from a 500 motor. maybe look into bracing that as well, or upgrade to a boxed (possibly aluminum) swingarm with a fatter rear tire(you may want to upgrade the rear wheel too)
whatever you do, keep us posted
Scott

OK, So I will go with the 550 setup, no need to spend too much, Cant get more cubes so...airflow...

Is it possible to get a 4 valve per cylinder head onto the 550 barrel block?

all the 4 valvers were liquid cooled, best bet is to go for a set of flatslide carbs and get someone like Neville Lush Racing in SA or Rod Tingate Engineering in Vic to point you in the right direction for oversize valves, cams and port work.......

a custom head would also be tons of cash. a set of aftermarket cams a good port job, and possibly OS valves would really help. make sure to get a free flowing aftermarket pipe, and possibly larger carbs if you do this to get the most out of it. its a combo that makes HP, not 1 or 2 things.
I think that the gpz550 cams would be a fairly cheap upgrade(I think they fit), but not quite as radical as aftermarket cams.

I have a spare head and cams, so I'm chasing getting the cams reprofiled,and I will have a go at cleaning up the head myself.

What size flatslides should I be looking for? There is a set of 37mm from a FZR750 on eBay just now.

Any idea what other bikes had the same spacing and/or sizes as the 500/550?

Thanks, Steve

schambers wrote:

What size flatslides should I be looking for? There is a set of 37mm from a FZR750 on eBay just now.

Any idea what other bikes had the same spacing and/or sizes as the 500/550?

Thanks, Steve

Only the 400/4 (Japan only?) and the liquid-cooled 600's.

Best bang for the buck would be to ebay a gpz550 motor. You'll have to run pods instead of the airbox unless you can get an 81 gpz motor. The gpz550 motor has higher compression pistons, different cams and different jetting. It also has the oil pan with oil-cooler fittings, which you'll need if you are going to get more power out of that block. The trans, crank, and just about everything else are the same as the standard 550 and LTD 550 for 80, 81, and 82. Supposedly the gpz head is ported, but I can't verify that. 82/83 gpz requires different carbs, but the standard carbs can be made to fit by modifying the carb holders from the standard or LTD. The center to center spacing is the same on the carbs, but the later ones have larger throats and larger ports in the head.

Post edited by: loudhvx, at: 2006/11/14 03:21