Looking to buy my first Seadoo boat need for some advice.

[petrol]

Hello all, I'm looking at buying a 97 seadoo speedster the engine is the ( 712 ) and its 718CC for $1600 with a trailer. I have done some research and i figured it makes 85hp and can go up to 60-70 km/h A local in my building is selling it and it has not ran in at least 2-3 years. He gave me to key to try and mess around with it and try to start it. I have worked on many cars modifying things to make more power so i'm good with tools but have never touched a two stroke. I have not tried to start it myself but I will be this weekend.

Any ideas why it will not start? any common things like the starter motor? spark plug cables? or anything?

Any things to look out for? cracks? weak points in the hull or engine wise?

I'm open to any advice, I'm on a tight budget but want to own something nice not looking to go nuts just a nice little machine.


Thank you!

 

[LouDoo]

Hi and welcome to the SeaDoo forum. I think we need a little more information, ie, will the motor turn over? If the motor does turn over do you have fuel to the carbs. and do you have spark?

BTW what you are buying is a boat not a PWC so if you don't mind I will move this to the proper forum and re-name the title for you.

Lou

 

[petrol]

Okay perfect thank you, I will be trying in the next few days to start her up and I will post back just wanted some rough info before I went into this project. Like some feedback on the engine or basically any useful info

 

[LouDoo]

The best advice I can give you is to download a service manual, you can get one from this site if you join as a premium member or just google for one.

Lou

 

[Waterluvr]

Start with the basics Petrol, you need compression / ignition / fuel-oil mixture to see if it will run. First off, get a compression tester and squirt some 40:1 mix in the plug holes so that top end isn't running dry when you crank it over. 2 strokes can score a piston in a real hurry and you want to check that hasn't already happened. You also need to make sure there's some fresh pre-mix in the tank so the fuel pump and carbs can feed the lower end when you first start cranking it over, you don't want a dry crank or rods either. Use a fresh known marine starting battery, Rotax's have some expensive electronic control's that don't like low or erratic voltage. See if it will turn over initially with the plugs out for just a short crank.

Use the plug wire grounding terminal and see what you have for compression (psi) on each cylinder, the closer you are to 150+ psi on each hole the healthier the engine is. If it's low or there is a big difference between cylinders you have expensive problems to solve if you buy it.

Make sure both plugs fire when you ground them near the plug hole in the head or use an ignition tester like mine with the ground lead connected to a plug if you can find one. I use a Stevens marine S48H spark checker, makes verifying ignition a snap.


If you can verify that compression is in good order, you have ignition then just plan on pulling the carbs and rebuilding both of them, the fuel and accelerator pump right away. After sitting that long it's not optional for the health of the engine even if it seems to run ok. Replace the fuel filters and the in line oil filter, Rotax motor's require Bombardier's full synthetic Xps-2 oil don't use outboard 2-stroke oil in them.

 

[petrol]

Start with the basics Petrol, you need compression / ignition / fuel-oil mixture to see if it will run. First off, get a compression tester and squirt some 40:1 mix in the plug holes so that top end isn't running dry when you crank it over. 2 strokes can score a piston in a real hurry and you want to check that hasn't already happened. You also need to make sure there's some fresh pre-mix in the tank so the fuel pump and carbs can feed the lower end when you first start cranking it over, you don't want a dry crank or rods either. Use a fresh known marine starting battery, Rotax's have some expensive electronic control's that don't like low or erratic voltage. See if it will turn over initially with the plugs out for just a short crank.

Use the plug wire grounding terminal and see what you have for compression (psi) on each cylinder, the closer you are to 150+ psi on each hole the healthier the engine is. If it's low or there is a big difference between cylinders you have expensive problems to solve if you buy it.

Make sure both plugs fire when you ground them near the plug hole in the head or use an ignition tester like mine with the ground lead connected to a plug if you can find one. I use a Stevens marine S48H spark checker, makes verifying ignition a snap.
View attachment 26107

If you can verify that compression is in good order, you have ignition then just plan on pulling the carbs and rebuilding both of them, the fuel and accelerator pump right away. After sitting that long it's not optional for the health of the engine even if it seems to run ok. Replace the fuel filters and the in line oil filter, Rotax motor's require Bombardier's full synthetic Xps-2 oil don't use outboard 2-stroke oil in them.

Okay thank you for the info i'm going to see how it goes.

 

[Waterluvr]

I hope it checks out for you, besides it's a good way to get to see how everything works while you're evaluating it. One more thing, make sure the oil tank isn't empty in the boat and line is full of oil down to the motor injection pump before you start turning it over so it's feeding lubrication that way also. Don't be shy about pulling the air cleaner and adding pre-mix right to the carb's and through the plug holes, unless that engine was stored properly with fogging oil critical wear surfaces have been exposed from the exhaust side of the motor to atmosphere and are dry.

Even if it was fogged, that's a long time for it to have been sitting and there's probably a reason why it was left that way, most of those reasons are due to work needed and the cost's associated with doing it you just have to find out what it is.

I'd lower the trailer tongue and take a flashlight under the back of the boat and look up into the pump housing intake grate to get a look at the impeller blades and wear ring to see what condition it is in, inspect the back of the pump housing and see if the steering, shift and throttle cables all work freely.

If you run into trouble ask for help, better to wait and ask question's than to risk damaging something. Do some reading on the Sea Doo DESS security system and the MPEM board so you have an overview of how that all works, there's lots of threads here about it you don't want to do anything to damage that it's a pricey mistake if you do.

 

[petrol]

Great info thank you i will be taking a look this week im going to do more research i could not find these forums before but a lot of pinned threads are good also!

 

[Bobbuff]

Hey just wanted to chime in and say Waterluvr that was a great response. Not only did you help petrol out but I am also going to use the info for my project as well. Some of us not saying petrol is but I am very new at this mechanic stuff and you simplified it very well. Thanks. Petrol I bought my second Sea doo Sportster 1800 this year. I had one last year and I could only actually get it running right one good time all season because I didn't want to listen to anybody on here. Needless to say I sold it and hated myself for it ever since. So this year I bought another sportster and am going thru the same process you are. Once its running you will love the ride. Enjoy!!!!

 

[Jims5543]

One last thing, do not jump it, put a fresh battery or make sure the master switch is turned off if you charge it up. Jumping or charging can damage the computer.

 

[Nosnibor]

All this is good info...I'm even less mechanically inclined but I hope someday I understand, lol. I've never seen inside a motor and I'm afraid I would break it worse. I need someone to show me. Anyone know some good videos I can study?

 

[Waterluvr]

All this is good info...I'm even less mechanically inclined but I hope someday I understand, lol. I've never seen inside a motor and I'm afraid I would break it worse. I need someone to show me. Anyone know some good videos I can study?

If your really interested in learning how 2 and 4 stroke engines work look into taking a basic power mechanics class. Lots of school systems offer that as adult education programs or continuing education opportunities for very little cost. Getting your hands into single cylinder power equipment engines is a great place to start and learn.

 

[Nosnibor]

If your really interested in learning how 2 and 4 stroke engines work look into taking a basic power mechanics class. Lots of school systems offer that as adult education programs or continuing education opportunities for very little cost. Getting your hands into single cylinder power equipment engines is a great place to start and learn.

I'd basically just want to know how to fix my boat personally. I guess I could just pay a shop to do it but I hate paying for something if it's easy enough for me to DIMyself.

 

[Jims5543]

You tube can teach you most anything today.

From paying guitar to working on cars or boats.

I really need to get a screen mounted in my garage. I am always playing You Tube videos of DIY how to videos when I am attempting something I never have done before.

 

[petrol]

Great into guys I'm buying the boat in a week with a seadoo trailer for $1200 bucks I have yet to even look at it but regardless i'm going to get her running. I will post some pictures for people to take a look and give me some feed back. I just have a few questions for now:

What are the best plugs people recommend the manual lists NGK, I loves these run them in both of my cars but what specific temperature and what gap is everyone using and what should I be aiming for?

What is the best oil brand and weight/viscosity everyone uses?

What octane of fuel is everyone using? the manual says 87 is this the best option?

Thank you.

 

[Waterluvr]

Petrol, at the very least you should verify that the boat has a good working MPEM module and the plugs are firing. If you wind up with a bad MPEM control module and wind up needing an engine on top of things you might be in a world of hurt buying a non runner like that.

The pumps and driveline can add up in a hurry as well and commonly need a total rebuild on boats like that. There's a reason why someone walked away from it and let it rot. You'd do well to find out why before you pay good money for someone else's problem.

 

[petrol]

Okay that is a good point I'm going to test it out and see what I find thank you!

 

[Waterluvr]

Okay that is a good point I'm going to test it out and see what I find thank you!

That would be wise before you pay anything for it, the costs of repairs can easily exceed the value of the boat. You might do much better buying a running boat in reasonable condition that can be evaluated properly to establish a fair value.