98 GTX limited with 951 motor cylinder issues

[slowboatn]

Ok I removed the cylinder awhile back. Found the rave valve stuck in its orifice. A bolt was too long and pushed the metal down on it. Got it out no problem. Took the the cylinder off. Went to a machine shop today to see what they could do. The noticed some wear in one of the cylinders. So they think the best thing would to be a complete rebuild of the pistons and cylinder. I checked the piston in question. It has some scratches on the side where it came into contact with the cylinder. So, for about $470 they will machine the cylinder and get new pistons, rings, and complete gasket set. It comes with rings and pretty much everything.
How difficult is it to get the pistons off the rods? Do I need to remove whats left of the motor in the hull to work on it from here on out or can I do it in the hull?
IS THERE ANYONE IN THE SOUTHWEST HOUSTON AREA THAT CAN COME HELP ME WITH THIS???? Seriously! I would feel much better if I had someone that has worked on these motors and could kinda show me the ropes. I want to get this thing running so bad. I appreciate any and all help. Always do and will.

 

[slowboatn]

Got the pistons off. One has damage. I'll post pic of it in a bit.

 

[SabrToothSqrl]

You can technically do it all in hull, but you have to remove the motor mount bolts to tilt it anyway.

Also, what's going to happen to that crank after 15 years of use? I highly suggest replacing it or, if you don't rebuild these daily, having any qualified shop do it, and getting a 1-2 year warranty on the engine.

I used to do these, did a few, and for the time, stress, and did I do it right factor, I've moved on to having a shop do mine

 

[slowboatn]

EVen though it has been 15 years the motor has very low hours on it. I had 2 shops and about 20 people give me instructions on how to check the crank and rods and bearings. I did them all and results are positive. So far. GOD willing it will survive the cylinder rebuild. I'm not going for more hp or torque or anything. The 2 shops close to me only do the cylinders and stuff. They don't mess with the crank or counter balance shaft end. I appreciate the advice. It will be very much considered.

 

[Robj]

I would listen to the rodent, like I said in a previous post he is one of the 951 experts. Really hours on a 15 year old motor has nothing to do with it. If it is not stored properly it can take out the crank bearings in no time. Your best bang for the buck is to get it rebuilt by a shop and it comes with a no fault warranty. You should compare what it will cost you to do a top end at the shop vs a complete engine rebuild.

I was looking into rebuilding my 787, but when I did the math, I decided to send it out. Tom from SES would guide me through it, but there are so many little things to look out for, just not worth it for me.

 

[slowboatn]

How much does it run to rebuild the whole engine? That worries me. Trying to stay on a budget here and not spend too much.

 

[kicker]

To give you an idea

SES premium is $1200, the standard is $1049
SBT premium is $1495, the standard is $1195

both shops offer a 2 year no fault warranty on premium and 1 year on standard.

You will also have to add some shipping costs, not sure if either shop pays shipping one way.

 

[Minnetonka4me]

Everyone is giving you proper advice. The 951 is under engineered so any little issue and its coming apart.

BUT...you just never know. I have a customer's machine in right now; the motor had to come out for a new bendix and the PTO cylinder is a bit beat up. The customer decided its pretty beat so he just wants it put back together and if he gets a tank of gas thru it he will be happy. Luckily he understands he is taking that chance.

Im fine with that...hopefully the cases dont get damaged in the process cuz it will be a parts machine.

 

[Minnetonka4me]

Everyone is giving you proper advice. The 951 is under engineered so any little issue and its coming apart.

BUT...you just never know. I have a customer's machine in right now; the motor had to come out for a new bendix and the PTO cylinder is a bit beat up. The customer decided its pretty beat so he just wants it put back together and if he gets a tank of gas thru it he will be happy. Luckily he understands he is taking that chance.

Im fine with that...hopefully the cases dont get damaged in the process cuz it will be a parts machine.

He isnt going to have $500 into a top end rebuild though...your gonna be pissed if the crank happens to grenade and takes out your cases, not to mention your new $500 top end.

 

[slowboatn]

Just curious. I don't know that is why I'm asking. What is the reasoning behind all of this? The whole complete engine rebuild? I've done motorcycles that just needed a top end and of course many vehicles and they ran fine for a long time. I don't know how much diffferent a jet ski motor is from them. Is it just due to age? Cause I never abused this ski. Ever. Maybe it was before I got it. I never ever had it seize up on me. I think the previous owner told me that they had to do some work on the cylinder before but I'm not sure. I will have to find out.

 

[smc0922]

The 951 is "fragile". It doesn't take much to have one of these motors give you trouble. The issue here is the crankshaft, given its age the seals are no longer new, and a failed seal equates to an air leak and lean running condition. With that said, the big question is WHY do you have a bad cylinder, not "should I just do the top end". I understand you had a stuck RAVE. But that contact means some metal shavings/debris was tossed around in the engine. You found SOME of the damage on that cylinder and piston, but who is to say that is ALL of the damage. When something like that happens many people just fix the RAVE, do a cylinder hone/bore and a new piston, and run it. Then it grenades or breaks shortly after because debris took out a crank bearing or ruined a seal and cooked the motor.

All in all, your $500 top end is halfway there to a rebuilt motor with a warranty. Do it right, do it once. Especially with this motor.

 

[kicker]

Just curious. I don't know that is why I'm asking. What is the reasoning behind all of this? The whole complete engine rebuild? I've done motorcycles that just needed a top end and of course many vehicles and they ran fine for a long time. I don't know how much diffferent a jet ski motor is from them. Is it just due to age? Cause I never abused this ski. Ever. Maybe it was before I got it. I never ever had it seize up on me. I think the previous owner told me that they had to do some work on the cylinder before but I'm not sure. I will have to find out.

Seadoo's are much different from other 2 strokes, boat motors, motorcycles etc. The main reason is that water is used in the exhaust system to cool the exhaust and muffle the noise. The exhaust system is never totally dry or without some water in there. This causes humidity and that humidity makes its way down to the crank, bearings and seals. This is why bombaridier recommends that you fog your engine if not in use for more then a couple of days.

If you owned your ski since new and fogged it religiously and have had no other problem you "might" might be ok with just a top end. There have been many times with these that someone has done the top end and the extra stress put on a tired bottom end takes the bottom end out after a few hours.

You could proceed with just a top end rebuild and possibly get 100 hrs out of it, but it is a gamble with these things. The gamble is not just the $500 for the top end but like Minnetonka mentioned if that crank blows up and takes the cases out you will be into a rebuild for $1200 plus the repair on the cases and crank, that will get you close to $2000 plus your time.

Nobody is looking to spend your money but just give you sound advise, in the end it will be up to you.

 

[SabrToothSqrl]

I am also speaking from experience and having to put the engine in, then out, then in, again. Only to have a crank fail within 2 tanks of the new top end.

It's a lot of time, work, and parts finding to do this, and then you have to hope you got it right, and that a 15 year crank, rings, bearings, seals are up to the task.

Will it work? maybe. I'm sure it would. But your original engine lasted 15 years here. why not get another that will go in, and give you 15 more?

reassemble the pipe on a GSX or GTX a few times and you will know why you really don't want to do this more than once.

 

[bradw18]

im in the same boat as you. lost compression on one of my cylinders and just spend 400 on a new top end kit. i was gonna just install new pistons and jug and hit the lake... now reading this im second guessing things. but im like you id much rather spend 400 on it then 1200 or more on a motor

 

[slowboatn]

Now I'm scared. I didn't want to spend that much on the motor plus I can't find anyone around me that does the whole enchilada. I guess it will have to wait until I get the cash to do it all at one time.

 

[slowboatn]

Update. It's still sitting waiting on an engine. Wife wants me to get rid of it. I want to keep it and fix it but have 1 kid in college. So I'm weighing my options.

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[68ragtop]

At least your not rushing into anything..

Kicker hit it right on the head in post #12. I have built many 2-stroke snowmobile engines & re-used many cranks. if the bearing were good, they went back in. Almost no failures.

These seadoo engines are exposed to sauna like conditions. Most damage happens after they sit from a day of use. Exhaust ihas sitting water, condensation collecting internally & exposed metal starts to rust microscopically. IMO a 50 hour 10 year old ski used a couple times a year is at bigger risk of failure than a 300 hour weekly used ski for that reason. Seeing you have the time, tear the thing apart & inspect it. Its hard to tell how good the bearings are even out of the ski, but you can tell if failure is eminent. Any rust starting on the balls, needles or races & the clock is ticking.

When I first got into these skis, I freaked out a little to how exposed they are to H20

a new/rebuilt crank can run 400-500, so not a easy decision & you have to weigh the risks.

 

[slowboatn]

I still don't know what I'm going to do with it yet. The motor is apart for the most part. Issue is no money to replace said engine.

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[slowboatn]

I know it's been awhile but I am going to replace the motor. Yall know of anyone in the west/southwest side of Houston, TX that can do the work and be reliable? Or anyone in that area have experience doing it? I don't and have no time to do it.