fixing my Valves

hey guys ok i have a 81 kz 750 e2 now the bike seems to run ok but today i did do a compression test on it the results were dry test cylinder 1 80psi cylinder 2 105psi cylinder 3 90psi and cylinder 4 95psi now the wet test results 1 80 2 95 3 90 4 100 so i'm thinking valves need to be fixed because i figure the rings are ok i would like to get the compression back up i have never done this so what do i need and how do i go about this job im in ontario canada

Hello, 81kz750e2, and WELCOME to KZr!

If not doing so already, be sure the throttle is being held wide open during the compression test.

Good Fortune!

When you did the compression test was the engine fully warmed up to normal operating temperature and were all the spark plugs out as well as the throttle being held wide open as Patton stated?

If not, you should do the test again, otherwise the results are unreliable. If you find the compression is still below the service limit, I suggest you perform a leakdown test. This will help you identify where the compression is being lost. If you're not familiar with the leakdown test take a look at the bottom half of the page in this link. When doing this test you will be able to hear where the leak is - exhaust pipe = exhaust valves, carbs = intake valves, oil filler = rings, valve cover = seals, etc. Ed

kzrider.com/forum/13-bike-related/570322...hame?start=40#572221

Before you start tearing into it, do the basics, check your valve clearances they might be to tight.

ok so i left the plugs all in except the one i was testing and just took the spark wires off all of them then hooked up the battery charger onto it on bump start setting so it wouldn't die and i held open the throttle and held the starter button and let it turn over for a minute is that right or did i do the test wrong because the bike would run if i left the wires on the other plugs

Wow, I hope you didn't fry your bike's electrical system! You should never hook the bike up to a battery charger or another vehicle whose engine is running. Doing that can blow out electrical components on the bike. If you are going to charge the battery from a charger or a running vehicle unhook the bike's battery cables first.

The test you did is not reliable. You should remove all the SPARK PLUGS not just the spark plug wires, and the bike's engine should be warmed up to normal operating temperature BEFORE doing the compression test. Holding the starter button for a full minute seems excessive to me. If you do the test correctly you should only hold the starter button until the compression number stops rising.

You really need to consider buying a Kawasaki Service Manual. Every KZ owner who plans to do any maintenance on his bike needs to have one. It explains how to maintain, test, and repair things without creating a situation that may damage the bike. Ed

thanks for the advice i will do it again i do have a parts catalog and the service manual but just didn't have it with me so thought i would ask on here i'm gonna just do the test again with all the plugs out and no charger hooked up the plugs were all black on the ends too when i took them out yesterday too see this compression tester is old to so maybe its leaking a bit to but i am not to sure how to do this leak down test to figure out where the leakage is.

Regarding the leakdown test. Take a look at the link I provided earlier. It describes it. Ed

A leak-down test injects air pressure through the spark plug hole to pressurize the combustion chamber.

Can perform a poor man's leak down test by introducing compressed air into a spark plug hole and listening to where it escapes from the combustion clamber. This may be done at TDC or any other cam positions where both valves are fully closed. Top dead center (TDC) is when the piston is at its highest position. An easy way to tell TDC is by alignment of the T mark with the case mark when viewed through the timing window.

May introduce a spurt of compressed air by using a rubber cone-tip blow gun (rubber air nozzle) held into the spark plug hole. And of course keep holding it in position to keep air from coming back out the spark plug hole while listening for escaping air at other places. The air compressor should not be running while listening because the noise will likely drown out any sound of escaping air.

May alternatively use a portable compressed air tank.

Air heard escaping from exhaust port indicates exhaust valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from carb intake indicates intake valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from crankcase breather indicates loss of compression past rings into crankcase (perhaps worn piston rings or cylinders).

Air heard escaping from head gasket area indicates indicates loss of compression past head gasket (perhaps due to a blown head gasket).

A leaking valve may sometimes be resolved by adjusting the clearance to within specs.

A leaking head gasket may sometimes be resolved by torquing the head fasteners when the engine is stone cold (such as after sitting overnight).

Good Fortune!

hey so i took all plugs out today and held throttle wide open number 1 cylinder is still 80psi so i can see the piston at the top of the spark plug hole dunno where to see top dead centre i know you said through the timing window but where is that located at and i put compressed air through the number one whole and the air ic coming out the pods at the back of the carbs

You may want to invest in buying a Kawasaki Service Manual. No KZ owner should be without one. With that in hand and a few correct tools you will be able to learn all about your bike and perform regular maintenance tasks as well as troubleshoot & correct problems. If you have air leaking out of the pod that is attached to the cylinder whose piston is at top dead center you may need to adjust the valves. But you will need the manual and some tools to first measure the valve clearances to see if they need adjustment, and you definitely need it to adjust the valves. Trying to work on these bikes without a manual is like walking down a busy highway with a blindfold on. You usually can find the Kawasaki Service Manuals (skip Clymers or Haynes) on eBay. Just be sure to get one for your exact year/model bike as there are important differences between models. Ed