1994 Seadoo GTX engine may be toast

[vlmuke]

Last month a bought a 1994 GTX at an auction said it had electrical issues, got it home everything in the electrical box was new except the solenoid, changed it and boom it works, now I'm new to two stoke other than snowblowers when I got the thing It had 150psi in both cylinders, we have taken it out 3 times in those 3 times we have used about 3 quarts of oil in a little over 3 tanks of fuel, its been running great until this evening when I took it out, I added some Johnson 2 cycle fuel system cleaner filled it up and rode for about an hour the all of sudden it started losing power and it backfired so I just coasted in and loaded up and went home when I got home I took the plugs out and the front spark plug looked like it had been dropped or hit the piston and had almost no gap I check the compression and I got around 80 up front and 150 in the rear I looked at the piston and it didn't show any marks and the marks weren't shiny so I suspect That I may have dropped it and been like that, anyway could it be anything beside a top end rebuild as we were planning on taking it out over the weekend for one last ride before it gets too cold as it has been unseasonably warm here in Indiana, if not what could have caused it if the plug had been dropped could that have done it? for my first thought before I got home was I worked some crud loose and plugged up the carb up, I mean I don't think the 2 cycle cleaner could have done it, but IDK enough to know for sure could have been lack of oil or a cooling issue? Also how hard its it to rebuild the top end? I mean I can work on car engines or would it better to spend the extra money with a rebuilt engine?
Thanks any and all info would be appreciated.

 

[mwat65]

That's a 657 motor. It's easy to rebuild the top end in that motor. You can do it without pulling the motor. You need to find out what caused the loss of compression or it will do it again . Check your connecting rod . If there's play it could have caused your piston to hit the spark plug . If not go through your carbs again. I've never used any 2 stroke cleaner but I would advise against it. Maybe someone else on here can speak to that. Follow the manual on here for your rebuild.

 

[mwat65]

If you have any questions on your rebuild you can pm me. I've rebuilt several 657s and they are pretty simple.

 

[vlmuke]

Thanks for the reply, after messing with it some more today, I think I may have dropped the plug on the concrete as I kinda remember doing so but never looked at the gap but I put the plug regapped it and after cranking it it didn't close the gap, but now I am wondering if being having no gap was the cause, what about the bores wouldn't I need to get them bored or at least honed? I mean I was using about a quarter of oil per tank is that about right, I am not sure what the consuption rate is? and stupid me didn't check the little outlet in the back to make sure the cooling system is working, I mean any other possible causes? I mean do they go like that?

 

[mwat65]

I believe your oil mixture is 40-1 on that model. Someone correct me if I'm wrong. That puts you at a quart for ten gallons . You really should hook your oiler back up. It performs at a variable rate according to how much throttle is applied and will save you a lot of money in the long run. Yes you need to hone your cylinders at the least if they are in decent condition. You can buy the top end wsm kit through the site. When a cylinder goes down it's almost always because of a lean fuel condition. Rebuild your carbs with oem kits.

 

[mwat65]

Btw. What color are your fuel lines ?

 

[vlmuke]

I believe your oil mixture is 40-1 on that model. Someone correct me if I'm wrong. That puts you at a quart for ten gallons . You really should hook your oiler back up. It performs at a variable rate according to how much throttle is applied and will save you a lot of money in the long run. Yes you need to hone your cylinders at the least if they are in decent condition. You can buy the top end wsm kit through the site. When a cylinder goes down it's almost always because of a lean fuel condition. Rebuild your carbs with oem kits.

No the oil injection is hooked up, I just don't know how much its supposed to use per tank, so does each carb work for each cylinder?

 

[mwat65]

Sounds like your using to much oil if your injection is hooked up. It's a variable rate on your oil . Your oiler is connected to your throttle. If you run wide open a lot it's going to use more oil. Are your fuel lines gray? If so there's your problem. If your fuel system hasn't been serviced, carbs rebuilt , fuel lines changed, fuel selector valve changed your going to burn up another piston. The cleaner you used could have caused damage also. Hopefully someone else will give you some insight on that. I' don't know anyone who uses a cleaner on a Seadoo.

 

[vlmuke]

Yes, I have been running it alot at full chat, I know the fuel selctor works as I ran out of fuel the first time we took it out, and I switched to reserve and worked I know some of the fuel lines were changed as the have regular hose clamps as opposed to the factory crimped ones but I will look in the morning to see what is wrong with the grey hoses? just curious, the reason why I put the cleaner in was I don't know any of the history of the ski, I can take a pic of the plugs to show how its been running

 

[mwat65]

Google gray fuel lines on a Seadoo

 

[mwat65]

Have you pulled the head to see what your pistons and cylinders look like ?

 

[vlmuke]

No I haven't yet, I did look at the fuel line and from what I briefly saw looks like they have replaced, my water heater heater in my house took a crap last night so I have messing with it probably do it either tomorrow or monday

 

[vlmuke]

Here's the inside of the piston that took a crap what do you think happened a ring let go?

 

[mikidymac]

Running lean I would guess.

As we see here all the time dirty carbs and fuel systems kill engines quick.