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Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 2002 1200 stx-r. New pistons rings, new

Customer Question

I have a 2002 1200 stx-r. New jugs pistons rings, new rectfier/regulator, new gas diverter valve, stator results yellow to yellow wires 0.00 ohms, according to my chart the results are suppose to be .64-.96, however they put out 30-45+ volts when running, the green/blue.51 ohms(which is normal, battery gets 12.8-13.5 volts while running. on land revs like crazy, in water sounds good but will not go over 1/2 throttle or 35-3800 rpm's.
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Submitted: 1 year ago.
Category: Boat
Expert:  RSRBOB replied 1 year ago.

Hi and thank you for your question.

I am happy to help you resolve the problem with your Jet Ski. I do however have a couple of questions for you that will help me more fully understand what you are up against.

First, why did the cylinders, pistons and rings get replaced? Please be as detailed as possible.

Were the parts replaced with OEM Kawasaki parts or aftermarket parts for a Kawasaki?

Who replaced the parts?

Is a gas diverter valve also known as a petcock, or as Kawasaki calls it in their parts diagrams a fuel tap assembly? Why was it replaced?

As far as the stator, it is very difficult to measure less than 1 ohm resistance so I wouldn't worry about that. It sounds like you have good AC output on the stator leads so that should not be an issue. Even if it were, it would manifest itself as being a dead battery. The ignition system is a magneto system that does not use the battery for running. The battery's main purpose is powering the electric starter.

Unless you have already confirmed it, I suggest putting an automotive style inductive timing light on one of the spark plug leads and put the pump in the water and see if you are losing spark at half throttle. If the engine goes into a mis-fire, or does what ever it does preventing it from revving up, and the spark remains constant, you do not have an ignition/electrical problem. If the ski is on a trailer, you don't have to take it off the trailer for this. Just back it into the water still strapped to the trailer and do the test right there.

If you are not losing spark, the next thing I would like you to do is a compression test on all 3 cylinders. I fully understand those parts are new but we know we have a problem with the ski so we don't want to assume anything. Make sure when you do the compression test you leave the 2 spark plugs installed in the cylinders that are not being tested. Ground the high tension leads to a suitable ground. You do not want to actually run the engine while performing the compression test.

Lastly, I would suspect a fuel supply issue, quite possibly carb related. That however is the last thing I would suspect and definitely do not advise going into the carbs until we address the other points first.

Let me know what you find,


Customer: replied 1 year ago.
according to my compression tester(which I can't fully trust at this point) said the compression was low, so I got a set of SBT jugs piston ring, gasket set, I installed them, I had to put a new starter in as idler bearing was bad and trashed the old starter, which was the state i bought the machine in. Fuel Tap was very sticky so I replaced it. Carbs have been cleaner out all jets are ones suppose to be in there. I did put a new rectifier in as it was only putting 12.2 volts running now it's 13+v. I dont have a way to check the spark that I know of.
Customer: replied 1 year ago.
Actually I do have an inductive timing light.
Expert:  RSRBOB replied 1 year ago.

Thank you for the additional information.

Go ahead and test for spark at idle and revving it up and see what happens. It would actually be a good idea to check your compression again even if you don't trust your gauge. At this point, it is more about consistency than a number. Especially if your new readings are somewhat consistent with your old readings. Was the ski running poorly before that prompted you to do a compression test and then replace everything?

Let me know the results.


Customer: replied 1 year ago.
I bought the machine not running seller told me it needed a new starter, he didn't know(or maybe he did) idler bearing was bad so after reinstalling motor the bad bearing trashed the new starter. so out comes the motor again. The fuel pump is new as it was leaking from the start. After replacing idler bearing and starter had no issues getting it to start and idle. Just when under pressure in the water it would not go above 3600 RPM, So that's when the shotgun mechanics started. So the only thing that hasn't been replaced is the CDI ignitor Coil pack. It almost seems like it's in a limp mode if this machine has one. The water temp sensor and air temp sensors all check out and do what they are suppose to do.
Expert:  RSRBOB replied 1 year ago.

Thank you for the additional information.

The best thing we can do now is use the divide and conquer method to diag and repair the ski.

As I am sure you know, we need adequate compression, sufficient spark at the correct time, and the proper air/fuel ratio being delivered into the cylinder. When a problem exists or occurs, we need to divide those 3 elements up and find out which is missing or being lost. Once we know that, they we can hone in on that system and get more in depth with our diagnosis. I still do not suspect an ignition related issue but the timing light test will determine that. Not to mention it is non invasive and very easy to do. We can gain a lot of information with a very small effort on our part.

Let me know when you get that test done and what the results were. BTW, I would be careful about using too cheap of a timing light to do this test. Some cheap timing lights by design cut out if too many RPM's are detected. It doesn't mean there is a problem with the engine, just the test exceeds the capability of the timing light.

Customer: replied 1 year ago.
In looking down throat of carbs when hitting the throttle the venturi slides in the CDCV carbs do not look like they are operating(or sliding open). I've taken them apart but did not fully take apart the venturi housing.
Expert:  RSRBOB replied 1 year ago.

Thank you for the additional information.

That may or may not be a problem. CV carb slides react differently when there is no load on the engine compared to under load. One thing they should do is lift when you move them by hand, and should spring back down when released. If the diaphragms aren't perforated, there is no reason they should not operate properly while underway.

So far, I have asked for a compression test and a dynamic spark test. Have you made any headway on those?

If you think I am leading you in a bad direction and would prefer to work with another expert, let me know. I will opt out and open it up to others. that notwithstanding, at this point, without that information, I don't think I can help you. I am not a fan of guessing at potential problems as opposed to sound diagnostic procedures.


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