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I have a '95 WaveRaider DLX that I put a new 760 engine in to replace the OE 701 when it seized. I did the engine swap about a year ago (kept the 701 carbs, intake, exhaust, oil injection pump, etc) and have about 45 hours on the 760 with no engine problems. Recently (probably within the last 5-10 hours of run time), I had to replace a blown out exhaust elbow and also replaced a rear motor mount at the same time (alignment was not perfect, but I did not reshim it since it didn't look any worse than it had been for the previous 35-40 hours).
This weekend, I was out riding it at WOT when the motor shut down quickly. This happened at the end of a long ride right after some high load turning with 2 riders on the ski. The shutdown felt to me exactly like the 701 when it seized. I let it cool down a minute or so and started it up again. I went to about quarter throttle and it shut down again. I let it cool another minute and then started it again. This time I idled it for a while and then slowly built up the throttle on the way back to the dock. By the time I got back to the dock, I was at WOT and everything felt fine. I pulled the plugs and they looked ok (front cylinder a brownish color - rear cylinder more blackish), and I also didn't see anything amiss from what I could see through the plug hole.
The next day, I went out on the ski to test it out again. I warmed it up and then went WOT for about 15 minutes. Everything was going fine and I was about to bring it back in when it shut down again in the middle of a right hand turn (not very high loading). Once again, I waited a minute and started it up. I idled it a bit and then worked in more throttle, but the power seemed down a bit and then it shut down again. I waited a minute again, started it, idled it some more and made my way back to the dock. Once again, by the time I got back to the dock, WOT felt ok. While idling during flushing, I believe the motor is making more noise than it used to, but I can't say for sure if I'm just imagining that.
Today, I pulled the plugs again - they still look fine. I spun the motor on the starter without the plugs and don't hear anything out of the ordinary. A finger over each plug hole results in similar pressure and suction feelings for both cylinders. Both pistons look fine for the part I can see through the plug hole. Spinning the motor by hand also doesn't reveal anything out of the ordinary.
Could this problem be fuel or ignition related or is it more likely a seizing engine? The 701 broke the piston ring on the way back to the dock so that one was a lot easier to diagnose. I'd rather not pull the head off of this one to look for damage if it could be something more simple. If you think it is seizing, do you have any ideas why? I'd don't want to put a rebuilt motor in here and have the same problem again.
Thanks,
Zak
This weekend, I was out riding it at WOT when the motor shut down quickly. This happened at the end of a long ride right after some high load turning with 2 riders on the ski. The shutdown felt to me exactly like the 701 when it seized. I let it cool down a minute or so and started it up again. I went to about quarter throttle and it shut down again. I let it cool another minute and then started it again. This time I idled it for a while and then slowly built up the throttle on the way back to the dock. By the time I got back to the dock, I was at WOT and everything felt fine. I pulled the plugs and they looked ok (front cylinder a brownish color - rear cylinder more blackish), and I also didn't see anything amiss from what I could see through the plug hole.
The next day, I went out on the ski to test it out again. I warmed it up and then went WOT for about 15 minutes. Everything was going fine and I was about to bring it back in when it shut down again in the middle of a right hand turn (not very high loading). Once again, I waited a minute and started it up. I idled it a bit and then worked in more throttle, but the power seemed down a bit and then it shut down again. I waited a minute again, started it, idled it some more and made my way back to the dock. Once again, by the time I got back to the dock, WOT felt ok. While idling during flushing, I believe the motor is making more noise than it used to, but I can't say for sure if I'm just imagining that.
Today, I pulled the plugs again - they still look fine. I spun the motor on the starter without the plugs and don't hear anything out of the ordinary. A finger over each plug hole results in similar pressure and suction feelings for both cylinders. Both pistons look fine for the part I can see through the plug hole. Spinning the motor by hand also doesn't reveal anything out of the ordinary.
Could this problem be fuel or ignition related or is it more likely a seizing engine? The 701 broke the piston ring on the way back to the dock so that one was a lot easier to diagnose. I'd rather not pull the head off of this one to look for damage if it could be something more simple. If you think it is seizing, do you have any ideas why? I'd don't want to put a rebuilt motor in here and have the same problem again.
Thanks,
Zak