657x Fresh top end, Hydrolocked?

[exrider416]

I just freshly rebuilt my Sea doo 657x. Everything spun and moved smooth! Get it all back together and it cranked fine and smooth. Put it in the water on the trailer and go to crank it and it would only click. After further investigation my wire going to the solenoid was bad. After replacing it and trying to crank it again, it will crank and then stop suddenly in the same spot each time. I can take the shaft and spin it backwards and it stops and then go back forward and it stops again. Its basically stopping when either piston it at top dead center. I have removed the spark plugs as well and does the same thing! Since this has happened, it has made it once past that spot once, but when I put the plugs back in to try to start it, it did the same thing. Any information or anything to try is greatly appreciated!! I am about fed up with it!!

 

[Shortrun]

Did you measure the squish during assembly? Sounds like it is to tight.

 

[racerxxx]

Did you spin the engine over during the rebuild? I'd pull the head as see if you can spin it by hand.

 

[mikidymac]

I would guess that the pistons were installed backwards. The arrow must point to the exhaust manifold. At this point as others have said you need to pull the head and check. It just uses o-rings so there are no gaskets to replace.

If it was hydrolocked pulling the plugs would allow it to turn all the way over. You have something mechanical stuck.

 

[exrider416]

I will be pulling the heads tonight. I did install the Pistons with arrows toward the exhaust. I never knew of the squish test on two-stroke engines. I am familiar with piston to valve clearances. How do you make up for the difference, are there thicker base gaskets? Or do most just stamp out there own gaskets at that point?

 

[exrider416]

The motor spins freely 180. You can go counter clockwise to say 9 o'clock and then clockwise back to 3 o'clock, but that's it. At those points it stops

 

[mikidymac]

Checking the squish is done with a piece of solder and is explained in the manual.
However every aftermarket gasket kit comes with typically a 5 hole gasket that will work in 99.9% of stock rebuilds and run just fine. This is why that is all they include but to get it exact you will sometimes need to purchase different thicknesses depending on how anal you are about specs. Like I mentioned 99.9% of the time that gasket is fine and you would never notice a performance difference.

The only way the squish could cause the pistons to hit the head is if the pistons were wrong, the head was milled incorrectly or no gasket at all was used.
Even when I check engines with no gasket to determine the squish and the exact gasket thickness needed you can still freely turn the engine over.

My next question is did you count and recover every loose needle bearing when you pulled the old pistons out?

If you lost one it could be stuck down in the crank causing your issue.

 

[mwat65]

Amen on the needle bearing. My buddy's son is now riding a near mint condition 96 xp that was locked up . We tore it down and found one needle bearing. No damage to anything. Put it back together and runs like new. Btw he bought it for 300 dollars because of one needle bearing.

 

[mikidymac]

That kid needs to go buy a lotto ticket too. [emoji23]

 

[mwat65]

Yes he does. When I said it was locked up was not entirely true. It did the same thing. Turned so far either direction then it would stop when I guess it hit the needle bearing.

 

[nycdon73]

When that happens to me, the rotary valve shafts gear was Sheard. I could turn the engine over just about the same amount