Motor swap

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Been a while since I've been on here so here egoes my question. I've got a old 97GSX that I've gutted the electronics on and think the motor is good ( know I need to check before moving forward). But wondering if I can pull the motor out of a 92 SP and replace it with the one from the 97 without much problem? Would I be able to make the motor work with the old electronics from the 92? Thinking if so that old 92 body should fly with that larger motor.
Thoughts?
 
No, not easily. Electronics are completely different but engine mounts are completely different so you would have to do a lot of fiberglass work. It wouldn’t be worth it for that hull.
 
In an effort to clarify as opposed to contradict Miki's statement, my understanding is that the 587, 657, 657x, and 720 share a common mounting setup. As it has been described to me (through YouTube I believe), you can physically swap between any of those four motors with little in the way of mounting changes. The 787 (800) and 951 are significantly different than the 587-720 and thus, would be very involved to transplant into an older 587-720 machine (as Miki stated).

In order to get an older machine operating correctly and taking advantage of the additional power from an engine transplant, you will need to move the MPEM and impeller (possibly entire pump assembly) from the more powerful setup into the upgraded machine. While a 587 MPEM may run a 720, it will not allow the 720 to produce full power. Additionally, if you put the 85hp of the 720 through a 587's 56hp impeller, you will over rev the engine and not move very fast through the water. I also believe, but am not sure if, the exhaust system is sized to the engine so parts of it would need to be upgraded as well.

My interest in this topic is that I am considering a 657x transplant into my '94 GTS. Yes, I know, the 720 would be a better choice if I wanted the best power and to take advantage of more common performance parts but I already have two 657x engines in and two spare jet pumps for my '95 Speedster. My thinking is that it would make sense to keep all three engines and jet pumps the same.
 
The right and left pumps on your 95 Speedster have different impellers in them.
You are correct sir, I had not noticed that before. I will have to investigate this further. I have no faith that the previous owner of my boat had it set up correctly and I did have cavitation issues with my right engine last year. I assumed the problem was a worn wear ring but maybe I have the wrong impeller installed.

Anyway, my impeller issues do not belong in a motor transplant topic on the PWC performance forum, I will ask my questions on the boat forum. Thank you for the tech tip.
 
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