717 Motor wont turn over

[Themist456]

Just got a super cheap 96 SPX. Story is it was sitting for 20 years....however, it cranked right over wheb I picked it up.
Compression was good 147 and 150. So, I did fuel lines, cleaned carbs, etc.

Was cranking earlier today. However, once I was ready to try and start it, it locked up.

I took off jet pump, took off flywheel cover to ensure started was not jammed (it wasnt). The thing it, I could turn it counterclockwise using flywheel nut but once that piston reach TDC could not go any further. Pistons move freely counter clickwise. Took the head off and no obstructions and no damage.

Do I need a new crank? Any other things I might not be thinking of that could cause this?

 

[etemplet]

When you took the head off you were still not able to rotate the engine both ways?

Remove the starter.

 

[Themist456]

When you took the head off you were still not able to rotate the engine both ways?

Remove the starter.

Yes, after removing head still not able to turn it both ways. I will remove the starter but doubt it will change anything because I can see it is not stuck in flywheel

 

[etemplet]

Strange. Might be a rod bearing. Where are the pictures??? Need Pictures of the outside of the ski, engine and offending part.

 

[Themist456]

Strange. Might be a rod bearing. Where are the pictures??? Need Pictures of the outside of the ski, engine and offending part.

 

[Themist456]

Strange. Might be a rod bearing. Where are the pictures??? Need Pictures of the outside of the ski, engine and offending part.

Here is the video of my moving the crank. As you can see it's pretty easy to move but once I get to TDC on MAG no amount of force moves it.

 

[etemplet]

It should turn by hand. I've had a couple of skis that were just tight and it was the connecting rod bearing on the crank. The cylinders will come right off. 8 bolts and you'll be able to take a closer look.

You can try soft scrub and a blue scotch-brite pad on the hood. I do that first. If that doesn't bring it back all the way you can use a heat gun... carefully though. The surface has to be really clean or you'll embed any surface scum or dirt into the plastic.

You can get it looking better than this picture. I wasn't completely done. I loved this ski. PERFECT for me. Loved the 717 engine too.

 

[Themist456]

It should turn by hand. I've had a couple of skis that were just tight and it was the connecting rod bearing on the crank. The cylinders will come right off. 8 bolts and you'll be able to take a closer look.

You can try soft scrub and a blue scotch-brite pad on the hood. I do that first. If that doesn't bring it back all the way you can use a heat gun... carefully though. The surface has to be really clean or you'll embed any surface scum or dirt into the plastic.

You can get it looking better than this picture. I wasn't completely done. I loved this ski. PERFECT for me. Loved the 717 engine too.

View attachment 57860

So If I take the cylinders off and the crank isn't rusted should I just try and force the crank? Is that what you are saying? Or get a replacement one?

 

[etemplet]

So If I take the cylinders off and the crank isn't rusted should I just try and force the crank? Is that what you are saying? Or get a replacement one?

Well you can inspect it a bit. You'll find out of you have a connecting rod issue which means you need to replace the crank. From what you posted and your checks thus far I think it is a good possibility you have a crankshaft issue. Either way you need to eliminate it. In the picture you'll be able to see that much
of your crank and connecting rods and you'll be able to check the freedom of movement of each rod. Might help. Good Luck.


Luck.

 

[Themist456]

Well you can inspect it a bit. You'll find out of you have a connecting rod issue which means you need to replace the crank. From what you posted and your checks thus far I think it is a good possibility you have a crankshaft issue. Either way you need to eliminate it. In the picture you'll be able to see that much
of your crank and connecting rods and you'll be able to check the freedom of movement of each rod. Might help. Good Luck.


Luck.View attachment 57872

Crank is rusted up good. Going to part it out and still probably come up a healthy amount on top. I have no interested in spending a bunch of time on these. I already have 2 96 Xps

 

[etemplet]

I have yet to find a ski with an acceptable engine. All of them need work, most are junk in my area anyway.

On a side note: I have yet to learn the art of parting out skis. I'm always a buyer but I have lots of parts I can Part with.

 

[Themist456]

Feeling really dumb! Took the rotary valve cover and rotary valve off and guess what I am an idiot! First of all, exhuast and water box had alot of leaves, likely from mice. Some how a piece of metal got into the rotary valve..... pictures attached. Thankfully it did minimal damage I assume. However, I don't know what that metal piece is. I am always super careful when putting carbs on to ensure I don't drop anything. Should I put it back together and try to fire it up?

 

[Themist456]

Also, even with plugs out, I still cant turn it over by hand. Still have to use wrench on flywheel.

 

[estorm]

I found a similar piece in a 717 once - it was part of the upper rod bearing. If something started to break apart, but the engine didn't scatter itself, it probably will the moment you try to start it. I'd tear it down further.

 

[Themist456]

Dang! Assumed it was part of the crank. Just will part it out as planned. Thank you for the reply. I might of been stupid and tried to start it lol