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1994 Sea Doo GTX

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SkiDooStu

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Hello everyone!

I recently purchased a 1994 Sea Doo GTX 650 to rebuild. I pulled the engine, and found that one piston had a broken ring. I am now just getting it completely torn down to make sure there are no ring pieces in the bottom of the engine.

I have checked my axial play on my crankshaft and it is well within spec.

I just was wondering if there is anything in particular I should be wary of? I'm taking my cylinders to a machine shop here so they can tell me what size of pistons to buy.

It didn't come with a lanyard. I assume this model did not have DESS and I should be able to just get a standard lanyard from the dealer?

Sorry for all the questions, but I have a few more as well. I noticed an oil in and oil out on the block. Is this to lubricate the rotary gear? Does it just pump itself through constantly?

Can I bench test this any easy way without cutting out all the electrical to put it on a bench?

Thanks so much for any help!!! (BTW I got into Sea Doos a few years ago but I'm just getting back in. I'm a Ski-Doo guy from Canada, which is ultimately my passion.)
 
Update

I was trying to get my flywheel off (I had foolisly taken the cylinders off long before this occurred to me) by using a rag covered bar and placing it between the crank and one side of the case to keep the wheel from spinning. Yes folks... I am an idiot. Forgot we are dealing with cast aluminum here.

I successfully damaged the intake port. A piece chunked off. I think I found a replacement crank halve on ebay. Maybe I should just get SBT to build me an engine... So expensive though considering my crank is ok.

Anybody have opinions on this?

Here is a picture for everyone's amusement:
 

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SkiDooStu said:
Update

I was trying to get my flywheel off (I had foolisly taken the cylinders off long before this occurred to me) by using a rag covered bar and placing it between the crank and one side of the case to keep the wheel from spinning. Yes folks... I am an idiot. Forgot we are dealing with cast aluminum here.

I successfully damaged the intake port. A piece chunked off. I think I found a replacement crank halve on ebay. Maybe I should just get SBT to build me an engine... So expensive though considering my crank is ok.

Anybody have opinions on this?

Here is a picture for everyone's amusement:
Click to expand...

we have all done things we wish we have not of done. we learn very well from these types of mistakes. it seems the that the more $$$$ it cost me the more time I take to think when aproaching a task I have never done. It sure is hard to learn this way. I have been doing it for years. good luck robin
 
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Broken chunk...

Welcome to the forum.....I agree with Robin, we've all done things like this before.
Just this past week, I was trying to easy out a broken stud on my exhaust manifold. Well, I broke not one, but three Cobalt drill bits in it. Do you know how tough it is to drill through a Cobalt drill bit?...........Impossible!:ack:

I don't know the extent because the picture is a little blurred, but the 657 has no balance shaft and is a pretty simple and smooth running engine. But, since you broke that chunk on the inlet side, what does it affect? Is the casting affecting the bearings or connecting rods in anyway? Did it crack or break off into or around the oiling chamber of the rotary shaft? If not, then what do you have to lose in taking the casing apart, removing that broken piece of aluminum, and putting it back together? No real money lost in trying is it?.........With it not being a part spinning or really critical, I would probably give it a try. As long as you didnt' distort the face of casing, where the rotary valve connects...........:cheers:
 
Really? Think I should try it? It's a very tiny piece. It didn't break off "into" or "out of" anything at all. Nothing is going to rub onto it. I was just worried about fuel flow...

Opinions? I really don't want to buy a SBT engine. I bought this Sea Doo as a project for myself.

Any idea how I can get the flywheel off now that my pistons are already off? I ordered a PTO removal tool so I was thinking that I could use that to keep the crank from spinning...
 
It looks to me it may be ok as long as you can acount for all broken pieces I would thank a very good impact would take off flywheel for you. if you do not have one give almost any mechanic $5.00 and he well loosen nut as you wait. at least a small shop that is not trying to rip people off. it may get your buisness in future they may even do it for free. you probly have a friend or family member that has impact. good luck Robin :cheers:
 
I do not think you will need to build that spot back up but I can be wrong. it just does not look critical in photo. get some more replies to see what other people think. good luck :hat:
 
One of the ski-doo mechanics that usually helps me in another forum said that he would be concerned about fuel flow... That part that broke off has a planed down piece that looks like maybe it sends fuel in a particular direction.

I was thinking about JB welding it...
 
It looks to me like part of casting. may not have a great value. dont get me wrong I would not want it to happen to me. it's not pretty. Fuel oil mist is sucked all over the inside of the crank case then blown into combustion chamber. As long as you do not have a crack there or broke something that I can not see, I think you will be ok. wait for a few more replies to see what others have to say. :)
 
Good advice Robin.....

That's some good advice Robin. What the tech is saying is by engineering theory of how the dynamics of the engine works. And that's true. But is it really going to hur it? I don't think so. Like Robin said, when the rotary opens and takes in that breath of air with oil and gas, it's atomizing all the way through. I don't think that small piece is going to make to much of a directional flow change.
Do not use JB weld to put it together. Like Robin said, account for all your pieces and go for it. What do you have to loose. Unless you just want to shell out all the extra bucks, wondering in the back of your head, was it worth it?
Me, personally, I'd do it. Looking at where your break is. As long as you've inspected and can see no further fracturing or when you start going together, check the rotary very close to see that it's not going to be affected by it when going to high speeds......I really don't see why not!
 
Ok well I will keep you guys posted as to my rebuild. I will at least run some emery cloth over the sharp spots.

I'm not sure how I'm going to get the PTO off. Maybe I don't have to. Once I have the flywheel off there won't be much for me to use to steady the shaft again for PTO removal...I"m just looking for pieces in the case anyway...

Pistons.. >What should I use? Wiseco or something cast?
 
I can get full wiseco pistons on ebay for $214 complete with a gasket kit.. Seemed like a pretty good deal. SBT wants $273 but it didn't list a brand name other than SBT.. Do they contract someone out to make their pistons?
 
Agh! I was taking off the flywheel with a puller and didn't have much luck. So, my buddy was looking at the flywheel side as I was spinning the crank (using the rods in my hand) and it looks like the crank is out of round.

Hopefully SBT will still take it. Yowwza.
 
Either that or the flywheel came off kind of lop-sided and it's an optical illusion.

I very very lightly tapped the puller bolt. I can't believe that I would have bent the crankshaft doing that :S
 
Are you sure it's bent?

Me either. For you to actually see that it's bent, that means, it had to blow a piston through the side of the casing. You sure your seeing that right?
Anyway, SBT will take it in any condition. If there's major damage that they have to repair, they charge some welding fees, but that's it............
 
Well I'm considering that it might be an illusion. What I mean by that is that perhaps I loosened the flywheel a bit on one side... The lop sidedness might be making the wobble effect.

No pistons through the side. Just a broken ring on this thing. Good to hear about SBT. I'd like to do the rebuild myself so I will see what happens when I finally get the flywheel off. If it's still looking bent then off it goes.

So strange. Just a few taps. Can you use an impact gun to tighten the puller? I had it on it's lowest setting so it was barely turning at all (I couldn't stablize the engine enough to use a ratchet.) Also, I have even threading on all sides of the puller.

Thanks so much by the way for your responses. Very very helpful.
 
Well I got the puller back on. I'm trying heat, then ice... Then pentrating fluid. Then letting it sit for awhile...

I spun the crank again today and it still looks wobbly on the flywheel side. I'm wondering if such a problem can be fixed by a lathe?
 
Flywheel....

You are taking off the flywheel.....I've read through the post, rater quickly, but wondering why your removing the flywheel. Are you planning on replacing the crank? The pistons can be changed out without opening the bottom end.........but now that you have, you think the crank may be bent...which, if it is, good thing you did. I'm just wondering why you were taking it off?..........
O.K....I read and see that when you broke off that piece of cast aluminum, that was what you were attempting to do.....but I still don't know why?
 
Ok,

I was disassembling the engine because a piece of ring broke off and cooked one of the cylinders. I wanted to double check to make sure that no pieces were in the crank.

Now, the crank seems like maybe it's messed up. Maybe due to my banging, or maybe due to me using an impact gun to tighten the puller. I read read on another forum that this is ok, but maybe not.

So now I'm trying to get the flywheel and PTO off so that I can send my core back to SBT. I am having no luck at all getting this flywheel off. Penetrating fluid, heat, cold, hammer, etc. Hopefully if I leave it long enough it will pop...

Sorry for all the posts.
 
Call SBT....

Are you talking about he magneto flywheel or the PTO flywheel. No matter, if your down to the crank and all you have is that flywheel, call SBT's long distance, toll free number and ask to talk to sales or a tech. A lot of the time, they will work with you on these kinds of problems. They may tell you to just box up the crank and flywheel and they'll send a complete set back. It may cost an extra $25 bucks or maybe not....but hell, look at your labor!....you've blown that over twice!.........just a though:cheers:
 
Hello again. I had the engine profesionally rebuilt by Greg at www.badfishpwc.com

A great shop near my hometown.. Very nice not to have to ship all the way to Florida to get SBT to do it. ANyway, turns out that the crankshaft did need to be trued. Apparently one of the pins in the web was a bit out of wack. Anyway, I'm having him put new carb kits in too (I took them apart and there was quite a bit of rust) and time the rotary valve.

Once I get this thing all hooked up electrically and all fuel and oil lines, should I take it to a dealer for alignment? I am getting a new wear ring too. My bearings and shaft in the pump all seem to be within tolerance as per the manual.
 
Hello!

I finally got this thing all put together and it's running great. The exhaust is cool and the head is not overly not either. I can see water in the lines.. However, I don't see anything coming from the "tell tale" hole... Should I be seeing this at idle? I've never tried to look around to see if it has anything coming out at full throttle....

-Stu
 
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