compression test question

[bigJake]

I got great instructions from Karl (below) on doing a compression test, but I have a stupid question. I see 2 studs right next to the battery, between the battery and where the coil wire plugs in. Im assuming these are the plug cap ground studs where I am supposed to plug the wires while doing the test, can someone confirm I'm looking at the right studs? This is on a '97 GSX. Thanks

You'll need a compression tester. Go to Auto Zone. I think they sell for like $25.00. The compression gage, will screw in the cylinder head in place of the spark plugs. To test compression, remove both spark plugs. Place spark plug caps on the plug cap studs near the cylinder head to ground the empty caps. This completes the circuit of the ignition electrical system and prevents any electrical problems from the caps being un grounded. Using the correct adapter for the threaded end of the tester,( same length of the spark plug threads length)screw in the tester in one plug hole. Hold the throttle wide open. Push the start button. Watch the compression gauge, when it peaks out at the most compression, let go the start button. Read the psi number. I would do it 3 times to be sure it is accurate. Check both cylinders the same way. The ideal compression is 150 psi per cylinder. If it is less, it's not a problem as long as they are close to being the same. If the psi is less than 90 it might need be time for a tear down and a rebuild. If the psi in 1 cylinder is say 140 psi and the other is 80 psi you need to tear down and repair. This difference is a lot and there is a problem. I hope this helps you.

Karl
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[kustomkarl]

Yes, those are the grounding studs...it keeps the Ignitions from building up electrical current and allows the current to dissipate. Always install the Spark Caps on those when turning the engine over with the plugs removed.

Karl

 

[bigJake]

Compression test results

I got the following compression test results:
Ski #1: 1997 GSX with about 80 hours on it
cylinder 1: 160
cylinder 2: 150

Results were consistent with multiple tests. This ski runs great, I did the test just to get a benchmark. Is the difference here (150 vs 160) of concern?
Both spark plugs were black with oily/sooty deposits.

Ski #2: 1996 GSX with about 80 hours
cylinder 1: 153
cylinder 2: 155

Results were consistent with multiple tests. Also, on this ski both spark pulgs were black with oily/sooty deposis. This ski runs ok at low speed but bogs down badly at mid-full throttle (seems like it is not getting gas). I checked/cleaned the fuel filter, but no help. I've seen other posts suggesting replacing the fuel lines on these skis for this problem as the gray lines supposedly deteriorate over time. Is that my next step? If Itake a line off and can blow thru it and it does not seem clogged at all, should I still replace? Or should I be going down another path?

Also, on Ski #1, I drained the SeeDoo oil from the feeder and return lines to the cranscase and from the resovoir (but did not drain the line to the injector pump, because i didnt see how to easily get to the bleeder screw) and refilled with Amsoil because that is what I can get easily from my local marina. Anyway, I wanted to confirm that the line to the cranscase is just gravity feed (and not pump/cycled back to the resovoir) because when i started the ski after changing the oil, both the in and out lines to the cranscase were full (the return line was full up to the level of the oil in the resovoir and air above) so I could tell that oil was not pumping thru the line (at least at the idle speed, i just started the ski for 10 secods out of the water). I just wanted to confirm this is normal, I didnt know whether I should see the oil pumping thru the line or not.
Thansk !

 

[kustomkarl]

Ok, your on the right track ...kinda. I'm not familiar with Amsoil oil, as I only use seadoo oil in my own machines. It has to be in spec with seadoo recommendations as follows;

Use High quality low ASH API TC Injector oil.
Do Not use NMMA TC-W, TC-W2 or TC-W3 outboard motor oils or other ash less type 2 cycle oil. Avoid mixing different brands of API TC oil as resulting chemical reaction will cause severe engine damage. Never mix Mineral or synthetics oil together.
as for the oil lines after changing the system over the Rotary Valve Shaft only uses the oil supplied as a oil bath. It doesn't get pumped back it just keeps it lubricated.

As far as boging down problem, it sounds like you need to remove the carburetors and clean them. If you're careful and don't tear or damage the diaphragms you won't need to buy a rebuild kit. Pay attention to the internal filters too. If you have gray fuel lines you need to replace them with black fuel lines available from auto parts stores like Auto Zone. Measure the length you need and bring a sample with you so you get the correct size. Replace one at a time so you don’t get them mixed up. If you need clamps replace them too. Use small stainless steel clamps also from the auto parts store.

Here is a step by step to the oil pump oil lines;

After you drain the oil from the oil lines and refill them, you have to be sure there is no air in the lines when the engine starts up or it will cause the engine to seize up. You need to fill the oil lines back up with oil. To drain the oil from the Rotary Valve Chamber, use a shop vac to suck the oil out of the hose…it’s the one that is 3/8” diameter. I attach the empty lines back to tank and fill the tank. The oil line going to the oil injector pump attaches to a elbow fitting on allows the oil to flow to the pump. I let the oil drain into the oil line to the pump first and put a small cup at the end of the oil line, to catch the oil coming out of the end of full line. Attach the full oil line to the elbow on the oil pump. There is a bleeder screw on the pump. Lay a rag under the bleeder screw. Open the bleeder screw till the pump has oil coming out. Tighten the bleeder screw. Be sure the oil is full in the small 2 lines also. Let the oil seep out the ends of the small lines to fill the lines as best as you can. Connect the 2 small oil lines from the pump to the carburetors. Where the cable is connected is a Disk,(pump lever) that the cable is attached to. Check that the mark on the pump aligns with the mark on the disk. Apply the throttle with the ENGINE OFF and check that the cable is in sync with the oil injector cable. They should move open and close at the same time. To bleed the 2 small lines and get the bubbles out, start the engine, on the water hose. DO NOT APPLY THROTTLE. Let the engine IDLE. Turn the Disk,( pump lever) that the oil injector cable is attached to, to full open so the air bubbles travel to the carburetors and leave no bubbles in the line. Don’t run the seadoo for more than a couple minutes on the hose.
For the Rotary Valve Gear Shaft, attach the hose on the tank and allow the oil to fill the hose and attach it to the case. Recheck all the oil lines and be sure they aren't leaking any oil. If you still have any questions give us a shout.

I think you have lots of homework to review. This should keep you busy over the weekend...

Karl

 

[bigJake]

thanks.
so the 150 psi in one cylinder and 160 in the other is ok?

I've never worked on a carbeurator, is there somewhere I can get step by step instruction for the cleaning you recommend?

 

[kustomkarl]

It's not the best, but it isn't bad enough to really get upset about. Give it another check in a few weeks to be sure it doesn't get too far out of spec.
JPX another moderator here has a grear link to help you out with the carb rebuild. http://seadooforum.com/showthread.php?t=5563

Do you have a seadoo shop manual? If not here’s an idea for you. You could join as a "premium member". As a premium member you can down load a authentic seadoo manual from the seadoo manual library. In the library is a variety of manuals for almost all years and models. You can view as many as you like on line as a PDF file, or download it and print it for your personal and private use. There are operator manuals and repair manuals for you to do your own repairs on your seadoo. The repair manuals have everything from troubleshooting, repair procedures to winterizing. It contains wire diagrams torque specs and pictures for disassemble and assemble instructions. In the spec sheets it tells everything needed to maintain oil changes, spark plug gaps, carburetor rebuilds and impeller wear ring tolerances. Click on the "Seadoo Manuals" link at the top of the page for more details. If you need any help or get in a jam, we are always here to answer your questions too. Premium members get priority when it comes to getting quick detailed answers.


Karl