Need piston expertise ..

Hi everyone. Starting to find parts for my 83 kz750 F1 shaft. Does anyone know if there is a piston I can use that offers more compression that will be a strait swap. I dont want to bore the cylinder heads so the 810 kit is out of the question. Ive heard that some gpz and zephyr models are faster so I am thinking about using gpz cams and cyl head and some pistons. Anyone know of some effective parts I can use. Any help is appreciated. Also since I have the shaft driven model, is using an aluminum (lighter) swingarm from a gpz(chain driven) out of the question? Many thanks.

Didn't the GPZ and shaft drive models (Spectre and the 1 year F/LTD) come out with the same compression ratio?
Why would you want to raise compression?
Have you done a compression test ?
There are other ways to gain cylinder pressure without changing pistons.

I was under the impression that more compression= more power. Maybe Im wrong. Theres always the chance that the specs I saw was for the turbo model.. Just looking to go faster. With hotter cams from the gpz I was thinking bigger jets... then domed pistons... what are the other ways to get more compression??

Turbo was around 8/1, early KZ750 was 9/1, late was 9.5/1 and takes different rings.
How does the bike run now?
You can advance the intake cam and or mill the head.
The reason for the compression test is to determined the condition of the piston rings.
If they are up to spec. fine,if not might as go big bore.
Do a search on compression test, 810, head milling and cam timing on this site.
Those subjects have been covered lots of times already.

bought the bike early summer and it rode ok. Its got some oil leaks coming from the cylinders. Seemed like it got really hot. Too hot. Got a complete gasket kit to do. I just want to make it faster. So are the gpz cams a good idea or no? Bike does have a little tick to it. And toward the end of the season it started to miss, just a little, off the line.

Have you checked valve clearence? Other routine maintenance?
And the 64,000 dollar question.




Do you have a manual?

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I done and 81 ltd 750 topend using 83 gpz pistons, cams and head slightly ported. With 29 smooths it was a VERY big improvement over the stock motor.

Les

justed ordered the factory manual. Been making due with the clymer haynes. Its not for my specific model though. Just ordered some feeler guages so ill be doing that. Started doing disassemble a couple hours ago. Found 2 plug wires were barely wound around the little screw in the cap. One was practically floating. When taking the exhaust off I found that all four of the little collars were cracked in half. Here are some pictures.

having trouble posting pics. Itried adding file and got nothing..

I guess I just need to find out what the differences are between the 81 and mine, what are 29 smooths? What differences could you see with the pistons?

GPz cams will work but all they do is raise the point where power is made. If you are expecting to drop in a set of GPz cams and have more low end torque you will be disapointed. VM29 smoothbores are WAY over kill for a stock motor. You will spend a bunch of time trying to tube them to run properly.
The easiest way to gain a bit more power is to insure bike is in a good state of tune then add a drop in performance filter and free flowing exhaust.