Need advise on engine swap! - PWC Forum: The best hang-out for Personal WaterCraft enthusiasts

josh650sx · 10-10-2011, 04:00 PM

Hey. So I ran into big problems with my 1989 650sx, got a real big hole in the bottom of my block somehow lol. I was looking at throwing a bigger engine in it, maybe a 750. Anyone know you if can just buy a 750 engine and hook it up to the driveshaft and its just that simple?

98yota · 12-27-2011, 12:04 AM

I did a parts comparison between your ski and a 94 JS750sx on Powerspotsplus.com's parts diagrams. The mounting plate for the 750 is the same as the 650, as is the coupler that goes between the engine and drive shaft. Unfortunately the simalarities seem to end there. The CDI unit, drive shaft, pump etc...are all different part numbers. So the engine should mount up fine but there are some necessary parts to make it work. The best option would be to find a wrecked js750sx and use it as a donor to your project. Hope this helps a little. Sounds like a great project! Keep us updated!

josh650sx · 12-27-2011, 12:19 AM

Ya that 750 engine idea seems to be more trouble that its worth. Lucking today I think I made a deal with a guy for a good 650 engine for 220. If the deal follows through then everything worked out perfectly. I bought a top-end for my other off a guy from this website that he said was ready to bolt on. It gets here and it needs to be rebuilt worse than the one I already had

I guess thats how it goes sometimes buying stuff over the internet

98yota · 12-27-2011, 12:58 AM

Well hopefully you have better luck with the $220 650 engine. At least have a couple spare cylinders! The nice thing with the 650 is you won't have to "makes it fit!"

josh650sx · 12-27-2011, 07:20 PM

ya hopefully haha. This all started out as a winter project of 1 jet ski, and I somehow worked my way up to 3

98yota · 12-27-2011, 07:55 PM

You could always keep a look out for a used 650 case then you could have a complete spare motor. You would be the most prepared at the lake then. Some think they are good with a couple gallons of fuel and some plugs, you'll have a complete engine, like to see someone top that!

josh650sx · 12-28-2011, 12:49 AM

haha ya true. Ive gotten so good at it from putting them in and taking them out I bet I can do a full engine swap in like 15 minutes

. So under your name it says you have two yamahas right? How do you like those? Do you know if there are a lot of aftermarket parts for them? We had a yamaha waverunner 3 years ago in Okoboji Iowa (1992). Since then my family sold our cabin and we were left with the waverunner and had no use for it. It sat around for about 4 years outside, then was stolen for two years until a family friend just happened to find it laying in a field, and since then it has been sitting in storage. A few weeks ago I decided that I was going to see what it would take to get it running, I expected it to be a lot. I put some gas in it, spark plugs, and hooked up a battery and it started right up. I was amazed. It is currently my only fully operational jetski

98yota · 12-28-2011, 02:34 AM

Yep you are your own one man pit crew!

I love my two Yamahas! I started a thread about them a couple days ago which has pictures of them if you want to check them out. The thread is titled "1993 waveBlaster 700 / 1989 wavejammer 500 project." There is tons of performance parts available for the Blaster, they are really popular with the free style riders and wave jumpers. The Blaster is sooo fun to ride! It sticks turns that seem like I'm going to black out! The acceleration tries to dislocate my shoulders every time I pull the throttle! It may not have the best top end around (45-48mph), but it sure gets there quick. The Jammer is also a blast to ride! It is just a tiny flat hull with a motor. I can't seem to stay off it because it's so fun. I have to get creative to get performance for this one. I did just put on brand new Protec extended ride plate I got for only $15 on eBay! Im going to post the mods on my thread. Have a good night!

freddys89 · 12-28-2011, 08:55 PM

what does an exteded ride plate do and where does it go? sorry if it seems like an idiotic question , im new to the jet ski world. ive never even been on one so as soon as i fix my tigershark, ima take it out and lose my jetski virginity lol

98yota · 12-28-2011, 11:06 PM

The ride plate is the plate that is mounted below the pump assembly. The ride plate is the point were your ski has contact with the water as soon as your ski plains out. Performance ride plates are extended or are shaped different to enhance cornering or getting plained out faster. The faster on the plain, the better the hole shot.