1992 seadoo sp wont start, only cranks over one time

[92seadoo]

Last week I went to the lake and my seadoo randomly died on me. I lifted the seat and saw that the rubber on the ground cable that covers the connection to the battery was melted. The connection to the battery was really loose as well as the ground cable being old and starting to fray so it wouldn't start after I tightened the connection. After I replaced the ground cable and made sure all of my connections were clean, I installed my battery which tested at 12.6v. Now the ski is doing the same thing as before. It only cranks one time when I hit the start button then makes a buzzing noise. I'm only mechanical when it comes to everything besides electrical work lol. Is there anyone that could help me decide what this problem could be? I was thinking maybe the starter but I would think it wouldn't crank at all if it was. Thanks

 

[92seadoo]

Also the "one crank" upon trying to start isn't a full crank either

 

[RodInEscondido]

Remove the cover over the PTO (rear of engine), remove the plugs and ground the plug wires. See if you can easily turn over the engine by hand turning the PTO.

Post back here and we can go from there.

 

[92seadoo]

So I just tried to turn the PTO and it's locked up...Ski had 175 compression in left cylinder and 170 in right cylinder literally the day before I took it out

 

[92seadoo]

 

[92seadoo]

Piston shattered. It has the block off plate for the oil injection as well as the oil tank with a little oil for the rotary valve..now just wondering how this happened

 

[mikidymac]

Why multiple posts for the same issue? Makes it hard for us to respond.
Your ski has more compression than stock an aftermarket carb and air cleaner. You need to be running higher octane than pump gas and probably lost the piston from detonating or an air leak.

 

[92seadoo]

The jetting has always been pretty rich, plugs are always dark not grey/white...ski has a lot of work done to it which is why there's more compression than normal. I bought it from my father in law who did the work and he mentioned running half race/91 octane would be best for performance. I took the engine out today, feels like the bottom end is shot

 

[mikidymac]

So what octane were you running?
With a modded engine the race gas is not for performance it is to make the engine not grenade.

 

[92seadoo]

Shell 91..I'll look into it more tomorrow to see if I can find anything else that could have caused it

 

[92seadoo]

With the head of the engine off, the crank will not move smoothly...could this be a problem with my crank bearings or seal? Just wondering if it's a pain in the ass to check out the bottom end

 

[mikidymac]

That's your problem. With the high compression and mods you should have been running race gas. You had detonation from too low octane and it eroded your piston. With the cylinders off and it won't turn over your crank is done.
If the cylinders are still on then the pistons are probably seized to the cylinder walls.

 

[92seadoo]

I appreciate your replies back to my thread! I took the cylinder housing off (which was kind of a pain because the piston was seized to the walls) and tried to spin the crank and it won't budge. I'd like to keep the seadoo rather than give up and sell it. I bought it with the ski not running due to the fuel tank lines being completely rotted so I replaced all fuel lines, did a carb rebuild, premix conversion with oil tank still feeding oil to the bottom end, and a lot of other little things. I've been lucky enough to ride it about 15 times until this happened and it's probably the most fun I've ever had on any pwc.

Now I do want to keep it a high compression ski that does run race gas because I'll be getting another seadoo pretty soon..so is there any type of brand that you recommend for the top end kit? I'm thinking of ordering my crankshaft through SBT, and I found a brand new head on eBay for a really good price. I saw SBT has a top end kit, just wondering if there's better pistons out there. And whether I should go standard, 0.5mm, or 1mm

 

[mikidymac]

Nope if you are going to keep it high compression and high performance the only parts that are up to the task are OEM cranks and pistons. SBT is fine for stock rebuilds but I wouldn't trust them past that.
As far as piston size you are going to have to see what's already in there and how much it will take to get the cylinders cleaned.