05-25-2011, 06:56 PM #1
New here and will be needing help (wow sounds like all the other noobs)
Ok, to start off i have bought (very cheaply) 2 94 SL750s, neither run, supposedly 1 did last year. So far i have picked up the 1 that i knew was gonna be a problem. It was previously worked on and apparently the mechanic didn't want to fix it nor put it back together so it came as a partial basket case but no parts missing (so far). Upon immediate assessment it had a bad PTO piston, but cylinder appears ok with no gouges or nicks, head is dinged from piston pieces and the block is full of water. So i began reading and hit up youtube and tore it apart, so today i finally got a hoist and pulled the motor. The center piston is also bad, piston from top looks fine but is broke where the rod attaches, cylinder and head look fine with no nicks or gouges, i got the water out of the motor and turned the crank by hand, which it does, and put oil in the block to let soak. The MAG piston and cylinder looks ok. So my question is...should I buy a used pair of pistons with jugs from 1 of you guys or ebay that has been compression tested, have these honed or bored and put in new pistons, use the 1 good 1 have and re-ring it? At the moment i am unsure and at a loss. Tomorrow I will crack the case open to see what the crank looks like but so far it seems like it will be ok. O and did I mention I am trying to do this on a budget of some sort.
05-25-2011, 07:09 PM #2
Welcome to the hulk.. maybe buy a used running one, a rebuilt one, or rebuild this one. whatcha think? feel like wrenching? or just drop one in..
its about 899 for a new one, 300.00 for 2 pistons and gaskets n stuff. could be a tad more if you plane on maintaining the ski such as carb rebuild, new fuel lines and filters. and add a triple fuel pump, the old ones get weak and blow out pistons.. thats a must for these engines. first.
about 200.00 to cover all that.
I would do some reading in the forum here and poke around on different threads and learn about your ski and what it takes to maintain it so it lasts a long time with reliability..
theres even updates about your particular model too. maybe it needs a slight upgrade or replacement of a certain item like a gas cap ete...
you can use the search function on the first page. give it a try. look up 750 engine, carb rebulding, that sorta thing. theres tons of info and pictures and were all here to help each other out..
just be prepared to spend some money on it, and have some tools to wrench with. and put in the time now, and youll have a good ski later on.. the sl is a fun ski to ride..
If the engine was full of water, then the crank is probably bad.. was this salt water or fresh? how long has the water been in there? if rust gets on the crank bearings, its cooked. need a new one..
if you were riding and sunk it, you could get it dried out quick and save the engine.. otherwise, probably not..
are you looking to just get 1 running or both? any mods done to them or are they all stock? any pics of them?
05-25-2011, 07:47 PM #3
thanks, and i have been reading and have it all planned for the fuel system, but i figured 1st things 1st i need to make sure i'll be able to get the engine to working condition. Its a freshwater ski all stock and i know it wasn't sunk i don't think the water has been in there over a few months if even that, it could have came from eh recent storms we've had it also has oil mixed in with it. When i crack the case tomorrow i plan on checking the crank and bearings out to see how they are. I plan on wrenching on it and have no fear of tearing into anything, I was just unsure of what direction to go for the cylinders/pistons as i have seen ppl do both and I am already prepared to spend at least $200 on the fuel system and gaskets but was trying to stay under/around the $500 mark overall. Especially since i know i have another to go pickup that i have no idea the condition of just that it ran last year. And yes my plans are to get both running.
05-25-2011, 07:56 PM #4
- Join Date
- Jul 2007
- near Toronto, Canada
That water is probably the determining factor. Once the crank shaft bearings develop rust, the engine won't last long at 6000+ RPM. For an engine that is flooded (usually due to sinking the ski) fresh water will start rusting the crank within a day or so (sometimes quicker). Salt water is even faster.
These crank shafts are hydraulically pressed together. Rebuild requires a crank shaft shop.
Do have a look at my signature links. Lots of info worth reading
05-25-2011, 08:19 PM #5
thanks for the info K447, I will evaluate the crank and bearings and have a verdict tomorrow
05-25-2011, 08:41 PM #6
- Join Date
- Sep 2006
That crank is toast.
Where are you located? In TX? I saw a decent deal on a complete 750 motor the other day..
05-25-2011, 08:56 PM #7
That crank is gone. I would stop on that ski and loom at the other ski maybe it will have a good crank. If you try to run that crank even though it's free it will destroy what ever else you fix. Don't wanna learn the hard way.
05-25-2011, 09:34 PM #8
ok well if its most likely junk i won't even try with it
bgaidan: yes in Texas, se of Dallas 45 miles, a complete 750 would be a whole lot better and what i have actually been hunting, just trying not to spend too much
05-25-2011, 11:08 PM #9
- Join Date
- Sep 2006
I think I saw those two on CL a few days ago...
I can't find the one I was thinking of now...may have been in Houston or something.
This has potential though:
This wouldn't be a bad donor depending how much he'd come down:
05-25-2011, 11:19 PM #10
i just found a running 94 sl650 locally with an intermittent spark issue for $300 and no title, if the motor will transfer over without issue that looks to be my route and i'll just do all the fuel system upgrade to it
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