A friend of mine has a completely stock 98 Kawasaki 900 STX with about 50 hours on it. The ski was running very well until he injested some water and hydrolocked the engine bending a rod. The ski sat for about two years and then he got a replacement engine from SBT.
He followed the SBT break in procedure until the part where you start running over ½ throttle. The ski idles well, and from a stop if you pin the throttle it accelerates good for 4 or 5 seconds up to about 30+ mph and then it starts to bog. If you back off on the throttle it will run very well at 30 mph. If you leave the throttle pinned it continues to bog and it has completely stalled a couple of times. If you accelerate to 30 mph and back off the throttle when it bogs, and then nail the throttle again at 30 mph you get the same bog.
We have checked compression and got 110 psig on each cylinder with my cheap gauge.
Have changed the spark plugs 3 times, thinking they might be fouling out from the extra break-in oil. We removed the gas tank and cleaned the in-tank filters, although they were very clean to begin with. Changed the inline fuel filter. Using new gas. Disassembled the Keihin CDK2 carbs and cleaned everything, although they looked great to begin with.
The only thing we didn’t do on the carbs is split the housing for the fuel pumps as we didn’t have the special Tamper Proof Torx Bit.
We did not check the timing, do you need to do that on this ski when replacing the engine? We are at a loss as to what to check next, any suggestions, comments would be appreciated.
Thanks,
Dan
He followed the SBT break in procedure until the part where you start running over ½ throttle. The ski idles well, and from a stop if you pin the throttle it accelerates good for 4 or 5 seconds up to about 30+ mph and then it starts to bog. If you back off on the throttle it will run very well at 30 mph. If you leave the throttle pinned it continues to bog and it has completely stalled a couple of times. If you accelerate to 30 mph and back off the throttle when it bogs, and then nail the throttle again at 30 mph you get the same bog.
We have checked compression and got 110 psig on each cylinder with my cheap gauge.
Have changed the spark plugs 3 times, thinking they might be fouling out from the extra break-in oil. We removed the gas tank and cleaned the in-tank filters, although they were very clean to begin with. Changed the inline fuel filter. Using new gas. Disassembled the Keihin CDK2 carbs and cleaned everything, although they looked great to begin with.
The only thing we didn’t do on the carbs is split the housing for the fuel pumps as we didn’t have the special Tamper Proof Torx Bit.
We did not check the timing, do you need to do that on this ski when replacing the engine? We are at a loss as to what to check next, any suggestions, comments would be appreciated.
Thanks,
Dan
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