I am in the process of rebuilding my 99 gsx ltd 951 due to water ingestion. The crank bearings are shot and lookin to replace them along with seals. Im just wondering why I cant find anything on the internet about them. I have new bearings and seals and looks as if I am going to need a press and bearing puller to dissasemble crank and the measurement tool to make sure bearings are placed correctly back onto crank. Does this sound correct or is there anything I am overlooking or missing. Thanks for your time and help is greatly appreciated
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rebuilding 951 crank
- Thread starter Gotme1
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SabrToothSqrl
Well-Known Member
Send it out and get it rebuilt w/a 2 year warranty.
I have the clymers manual but they don't describe the dissembling part to well. Guess I'll have to pick up the seadoo shop manual. And I would love to send it off to get rebuilt with warranty but I don't have the time or money at the moment and need to get ski running for a family vacation in a couple weeks. Any other advice or there?
Hate to say it, but you're dreaming if you think you can rebuild a crank by looking at the clymers manual. You need specialized tools and knowledge which is why most of the backyard mechanics on this forum get their cranks rebuilt by the shops that specialize in them. I don't even rebuild my own motors, I just buy a rebuilt with a warranty.
Sportster-2001-951C-Stock
Well-Known Member
Considering the price, availability and especially 2yr warranty, I'll contract a well known machine shop that specializes in remanufacturing multiple Rotax engines on a daily basis to do mine when it comes time. These engines weren't intended to be remaned by the DIY'er, IMO, just as many of the modern marine engines weren't, considering just the special jigs and fixtures required, let alone technique and specialized knowledge required. Heck, sometimes even they get it wrong, but not often hopefully.
At a minimum, I would have the rotating assemblies and cylinders remaned by them, but often that work precludes warranty so if life didn't go well I'd end up right back in the same boat I started from.
At a minimum, I would have the rotating assemblies and cylinders remaned by them, but often that work precludes warranty so if life didn't go well I'd end up right back in the same boat I started from.
Sportster-2001-951C-Stock
Well-Known Member
Look at it this way, try pricing out a 240hp Mercury 6cyl powerhead, now that can get expensive! True they last a long time, but I'm going to give this Rotax a run for it's money and treat it right, heck, it might go another decade, I've never worn out an engine myself but I've bought plenty of worn out ones I had to have reman'd.
We used to swap stuff around all the time back in the day, yank a cylinder off a motor with a blown bottom or thrown rod, something like that, and it usually worked out fine but we had amassed a pile of motors to yank parts from, or we knew someone who had a pile of motors they'd been hording. We made our own gaskets too, mostly from old shirt-box cardboard.
It's not entirely impossible to kluge stuff together, but these engines are considerably higher performance and even the rods don't have bolt-on bearing caps anymore. If the machine shop can disassemble one of these cranks and get it back together straight then that's saying something I think, I don't think I could accomplish that on my bench on the first or third tries.
Dr Honda
Well-Known Member
I have the tools im my shop to do it... and I will only rebuild a crank on something that is not made anymore. (like classic motorcycles)
You need a press, Fixtures, V-Blocks, dial indicator, a large hammer, calipers, Micrometers, feeler gauges... and talent. (It's an art to making a pressed-together crank "True" again)
Not worth the time.
You need a press, Fixtures, V-Blocks, dial indicator, a large hammer, calipers, Micrometers, feeler gauges... and talent. (It's an art to making a pressed-together crank "True" again)
Not worth the time.
SabrToothSqrl
Well-Known Member
I know you said budget; but time is $ too. Many shops will ship you an engine even before you send yours in...
I'm sure you are an excellent mechanic, but the 951 is an engine that does not like to built on a bench...
If this crank or something else goes... where will your time and budget be then?
I'm not trying to sound negative; and I hope whatever you choose works out, but boating ain't cheap. Not at $4/gallon!
And going budget, for me at least, has ALWAYS come back to bite me with more time, stress, and money.
I do have to ask, is the top end going to be all new? new pistons? sleeves? gaskets? new RAVEs? I'm not aware of the history of the engine.
If you are not in a hurry; I use SES, which is around $1,000 for a 951 engine.
that's an engine you are warrantied for TWO years for. Beat the piss out of it.
These engines only go 200-250 hours. Which, yes, is 10 YEARS. So, get a good engine, and get 10 more years from it.
Do a crank, and if your lucky, and really lucky... get a few seasons.
I'm sure you are an excellent mechanic, but the 951 is an engine that does not like to built on a bench...
If this crank or something else goes... where will your time and budget be then?
I'm not trying to sound negative; and I hope whatever you choose works out, but boating ain't cheap. Not at $4/gallon!
And going budget, for me at least, has ALWAYS come back to bite me with more time, stress, and money.
I do have to ask, is the top end going to be all new? new pistons? sleeves? gaskets? new RAVEs? I'm not aware of the history of the engine.
If you are not in a hurry; I use SES, which is around $1,000 for a 951 engine.
that's an engine you are warrantied for TWO years for. Beat the piss out of it.
These engines only go 200-250 hours. Which, yes, is 10 YEARS. So, get a good engine, and get 10 more years from it.
Do a crank, and if your lucky, and really lucky... get a few seasons.
I appreciate everyone's advice. I just ordered a rebuilt crank with 1 year warranty for 300 plus core. I have experience with building motors but this is a first to tear down a jet ski. I'm not used to working with cranks with ball bearings. I'm used to just removing crank and connecting rods, installing new bearings, plasti gauge, reassemble. The top end is also getting rebuilt, the damage was due to water ingestion. And go figure when I bought the ski, I was only informed that I needed a starter. Lol. But can't blame anyone but myself for that one. The cylinders had to be bored .40 over. Rebuilt rave valves waiting to get cylinder back so I can shave them and hopefully hit the water to start breaking this thing in. Do Yall recommend rejetting when Going 1mm over. I assume at least go up a jet size but I would like to hear from someone who has experience. I kno these 951 are very delicate when it comes to tuning. Thanks again everyone.
Sportster-2001-951C-Stock
Well-Known Member
Since yours is a 1999, I'm not exactly sure which jets are in your carbs from the factory, but, in the case of factory air box on my 2001:
You've got plenty of jetting on the high end, crack the high speed screws open if you need to. Normally the high speed screw is closed, and if you open it, it will supplement the high speed jet b/c the fuel through the adjustable screw orifice goes around the fixed jet.
I found my bone stock 951 carbs were too lean mid range, so went up two sizes to #80 on the mid range jet(pilot jet) but one size, from #75 to #77.5 would have been enough, I think, so I've got a set of #77.5's ready to in there. Just a little bit of 4-stroking on the low end the way it is with #80's in there, doesn't load up though.
Personally, I think the later 951(~140psi compression) needs a #77.5 if keeping the factory air box.
Larger if filter socks are being installed instead of factory air box but there are a host of other undesirable effects with those(water ingestion) so I think it's best to keep the factory air box unless you must have something else and insist on getting that last 50RPM's on the top end, LOL!
Sounds like you've got a good handle on the rest of it....
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Dr Honda
Well-Known Member
Yep... a 2-stroke crank is a totally different animal.
FYI... you shouldn't need to re-jet. The larger volume will draw more air/fuel. I actually find that they go a little rich when going over-sized. But, not enough to need a re-jet for a recreational rider.
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