Hot seize

[Matty67]

Hi

I’m new to skis but normally quite mechanically minded,

I have a seadoo xp800 (787) 1996 I have been stung with a ruined engine so I rebuilt the engine crank pistons ect all seemed good was on the lake for around 20 mins and the ski locked up solid! 1 hour later it was free as a bird and started,Iv had the head off and doesn’t look to have done any damage to the bores or pistons ect Iv checked the coolant lines and all seemed to be clear and tell tail pipe squirts water on hose I didn’t check at the lake as I was concentrating on everything else, I’m also running 40:1 premixed to try and eliminate oil starvation, any more input on this would be great

 

[burtshaver2021]

I would doubt it’s hot seized up if there’s no damage to the bores

 

[Matty67]

Ye true maybe worded wrong, whilst at the lake I removed the plugs and it would not turn over at all but like an hour later turned over freely

 

[burtshaver2021]

Ye true maybe worded wrong, whilst at the lake I removed the plugs and it would not turn over at all but like an hour later turned over freely

I’ve never had it happen, but hot seize works. When you rebuilt the engine what pistons did you use? Cast or forged? Did you measure the clearances? Ring end gap, piston to cylinder wall clearance. It does sound to me like a hot seize. Could also be running lean and/or blockage in the cooling hoses or hoses on in the wrong position. Either way, I would say the engine is running hot

 

[Matty67]

 

[Matty67]

I believe there forged pistons and all tolerance was followed,

 

[burtshaver2021]

What specs were followed? Manual specs or piston specs? If they are forged you wouldn’t use the same specs as in the manual

 

[Matty67]

It was 4-5 years ago when I built this and then stored away due to moving house ect so memory is now vivid
I believe the bores was measured to be able to order the piston in the right size,
I’m still digging and I may have some explanation, I read online it was 40:1 premix ratio and later found out it’s 30:1 when bedding the engine in, and maybe American gallons are not the same as the uk gallon
Really appreciate the messages any info on this is appreciated as I’m completely new to the game
Matt