Engine Replacement

[toolman60]

Hello All,

I think I made a mistake. I found a 98 GTX Limited for sale. I was getting it to have parts for the 99 GTX I have for my daughter. I knew it had blown motor. Hole in bottom of block. I got some pictures of the ski and it has been garaged kept and is in excellent condition. The pictures of it make me not want to get my needed parts off and junk the hull.

Looking online there are a few rebuild motor sellers for the Rotax 951. Anyone have an idea of what they charge without a core as they do not list it on the sites.
I am even thinking about looking for a good bottom end and then having the original motor rebuilt. I figure it has a broken rod so new crank rods etc to bring the bottom end back to OEM.

 

[NickCawks]

Most the sites will have you send your motor in and rebuild it then send it back. There are some sellers that will sell you a whole engine without a "core" meaning you just keep your motor and they send another. The only site I know of that will do a traditional core is sbt

 

[etemplet]

I'm just finishing this one. Yours is prettier. This one has a rebuilt engine from SES. Even though this was a good ski that had a good owner... it still needed dang near everthing. LOL I'm having trouble with the speedometer but she purrs like a kitten and roars like a lion. I love the color of this ski... looks kinda regal and I don't see many that color. They have a few one of a kind items on this ski. I bought an extra computer for it.

 

[toolman60]

Hi Gene,

I been watching and following that rebuild thread. Great work.

With the stupid prices they want for some of the part's on Ebay I decided to see if I could find a whole ski for my bit's and bob's.
And I found that 98 for sale. So I inquired on it and it has bad motor. But looking at them pictures of it I am not going to scrap it.

I will keep a watch for a rebuild core block for an exchange for rebuilt 951 for it. Or hope maybe to find a shop that has 1 rebuilt and just pay the core charge and get on with life.

 

[etemplet]

I just threw away a bottom end for a 951 and I have a few cylinders that are good just need boring. I sent a 951 to SES about a month ago. It was a spare but I'm gonna build another 1998 just like you got.

 

[etemplet]

Hi Gene,

With the stupid prices they want for some of the part's on Ebay I decided to see if I could find a whole ski for my bit's and bob's.

Yep, you can buy a whole ski for the prices these clowns want for a single part. Sad sad but we learn to work around the thievery and help one another. I am covinced you're jet ski pile is gonna rival mine. That ain't a bad thing.

 

[toolman60]

Gene and others,

I have not seen the block yet on the 98 GTX so do not know if it is repairable. Who is the best place to deal with a rebuilt engine 951 for this ski. Having looking around and finding another case may be a little trouble. I going to keep looking and see if I can find a set of lower cases before I decide to junk a hull.

 

[toolman60]

I had my heart broken yesterday. I was talking to my local Sea Doo repair shop and they use SBT. He called them while I was in the shop. He was told that a engine with no core would be 2000.00 more plus the price of the rebuild block. If I do not get lucky and find a good core block the 98 GTX will be junk.

I sit on it for awhile and see what shows up.

 

[clegg]

Enter seadoo 951 on e**y. There may be some no core required.

Where are you located?

 

[toolman60]

I am in Virginia.

 

[Mraw]

Call mel from 5 star pwc, he should be able to help you out

 

[toolman60]

Well I found me a short block turns smooth as silk.
Now I need someone to school me on the re builders.

Why would I want a welded crank that cannot be rebuilt in the future if needed by going with SBT rebuilt.
1800 $ Premium build SBT 951 Carb. 1350$ Standard Rebuild

SES :

1000$ premium build
900$ standard build.

Anyone know if the quality of parts are different between the 2 motors premium and standard build.

All I am looking for is a good reputable dealer that can rebuild my short block or do exchange and still be stock piston size when finished.

Please educate me on the do's and dont's I only want to pull motor/install 1 time.

 

[mikidymac]

Consider yourself officially warned about SES and FullBore as communication and return times are horrible at best, like you might not have an engine by next summer horrible.

No reason to weld the cranks but it is just what SBT does. WSM cranks are fine, I haven't heard anything good about HotRods cranks in years.

There is nothing special about SBT, it is ok quality parts and they lower the compression so it is a cheap engine ad you get what you pay for.

If it was mine, I would send my crank to Competitive Crankshafts and the cylinders to Group K and rebuild it myself.

The only difference in the standard and premium SBT engines is the warranty, it is the exact same engine they pull off the self.

 

[toolman60]

mikidymac,

I was looking at the gaskets for doing engine myself. I see that BRP list 3 different gaskets for the cylinder gasket. Can they make it any harder. Does the gasket kit from BRP include all 3 of them? Guess I need to measure the original and guess factor the crush and pick new 1 out the box.

Does that Group K do just back to stock work or they do the tweaking on all the cylinders they reman. I just looking to go back full stock on the ski for the daughter.

 

[mikidymac]

Group K can do anything you want from stock to full on Race work.

They offer 3 gaskets to set the piston the head clearance known as Squish. You need to measure it and see what gasket "your cylinder" needs. It is in the factory service manual.

 

[toolman60]

Group K can do anything you want from stock to full on Race work.

They offer 3 gaskets to set the piston the head clearance known as Squish. You need to measure it and see what gasket "your cylinder" needs. It is in the factory service manual.

mikidymac,

So after I get my new crank and counterbalance shaft installed in the crankcase.

1) I need to at least start with base gasket same thickness as original and set cylinders and head on and torque them down to measure my squish? That will tell me if I need thicker or thinner base gasket. Or do I assemble with no gasket run the squish test to determine my base gasket thickness

2) Or do I do the combustion chamber measurement and determine which base gasket I need?

Working on a 98 GTX 951.

 

[toolman60]

Unless someone changed the Info center and or MPEM this 98 GTX has only 95.2 hours on it. I know I got to see what caused it to knock a hole in the block now. Do not know what gauge they used but the head pipe is marked 150 psi on #1 and 2 cylinders. Makes me think someone put a top end only in this rascal. I did not think you could get the cylinders out of hull. I can tell the head has been off paint missing on bolt heads and nuts. Does not look like the motor was removed.

 

[mikidymac]

Check squish with no gasket then you select the gasket to get it to spec.

I tried the volume method once and it was a shit show. With new rings and a fresh bore it leaked the oil/gas mixture faster than you could get a measure past the rings. Never again.

 

[Mark 60]

Can someone tell me what I need to do? I have a 97 challenger with a signal 787 I am rebuilding it and I am at the point of a compression volume test the volume was 35.3 ml. That is within the tolerance 34.7 to 37.9 with no base gasket but my squish test is .070 to 0.73 out of tolerance .047 to.063. All at stock with new sleeves , pistons. Any ideas?

 

[etemplet]

Can someone tell me what I need to do? I have a 97 challenger with a signal 787 I am rebuilding it and I am at the point of a compression volume test the volume was 35.3 ml. That is within the tolerance 34.7 to 37.9 with no base gasket but my squish test is .070 to 0.73 out of tolerance .047 to.063. All at stock with new sleeves , pistons. Any ideas?

My 787's are always above squish tolerance. I measure the old gasket and put the same thickness. I use WSM components and what I believe is the crown or piston shape may be a little different when I measue squish so I am not comparing apples to apples with aftermarket parts. With WSM piston rings end gap is always be a tad over tolerance (around .020") All that may be because of the expansion rates of dissimilar materals during heating and in operation of the engine. I applaud you for checking all that stuff.

On a side note I muse about machining the cylinder bases to get the squish about mid-range in the tolerance but then... it's likely not gonna make the ski or boat faster... by much. None of that matters unless you're wide open and really... we'd rather the engines "last longer." Good Luck !!

 

[Mark 60]

Thanks for the info. I have another question regarding the counter balance shaft. The the repair manual said after putting the block halves together to put one OZ. of SAE W30 in the opening above the gear on the counter balance shaft . It shows a hole but mine is casted shut from factory. How do you get the oil in there? And what about the other side of the shaft would the seal burn up with no oil in there. The bearing is a sealed bearing. But the seal would not have any oil.

 

[mikidymac]

On the ones with the casting instead of the fill plug you have to add oil through the little hole in the case below the cylinder. I would use 2-stroke oil as it is slowly consumed and replaced as the rear bearings are lubed.

 

[mikidymac]

Thanks for the info. I have another question regarding the counter balance shaft. The the repair manual said after putting the block halves together to put one OZ. of SAE W30 in the opening above the gear on the counter balance shaft . It shows a hole but mine is casted shut from factory. How do you get the oil in there? And what about the other side of the shaft would the seal burn up with no oil in there. The bearing is a sealed bearing. But the seal would not have any oil.

Please start your own thread, just noticed that.

 

[Mark 60]

Sure will new here. Thanks for the info.