I have two 96 xp 800 seadoos that I rebuild both engine last winter, they run and start on trailer/ no start in water, so I did some searching on this forum about no starts in water, after checking compression on both skis they both are at 90psi in both MAG. an PTO. They have only about 10 minutes of run time in the past few weeks with a garden hose attached and running on trailer. Both engines are std bore 82.5 and I took head off both engines and checked to made sure arrow on piston was facing exhaust side. My guess is that I'm getting a leak somewhere in the case or between the jugs or the head. What your guys thoughts? Thks Zac
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96 XP 800 90 PSI after Renbuild
- Thread starter 96xp12
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Ok, I think your gauge is bad if all 4 cylinders are 90 psi. Try a different gauge and let us know the results please.
On land, put your digital volt meter on the battery terminals, try and start the engine what does the voltage drop to? Then try it in the water
Post pics of the engines if you can.
BTW, 82mm is standard bore on a 787 engine. 82.25 is the first over size, so I hope you didn't jamb 82.5 pistons in the stock bore because that is really the 2nd oversize.
On land, put your digital volt meter on the battery terminals, try and start the engine what does the voltage drop to? Then try it in the water
Post pics of the engines if you can.
BTW, 82mm is standard bore on a 787 engine. 82.25 is the first over size, so I hope you didn't jamb 82.5 pistons in the stock bore because that is really the 2nd oversize.
Yes I figured out what I did wrong Rookie Mistake I bought the wrong bore size, my bore on both skis is 82.5 and I ordered standard 82 bore top end kits, That would explain low compression, but constant compression of 90 PSI. Is the piston O.D. the same at 82mm as it would be at 82.5mm an just different width rings are used ? If so I can order the proper rings, and salvage the pistons.
wfo speedracer
Active Member
Ouch , that's going to leave some space in your wallet
What whiskey means I think is always be sure to take the pistons you're going t use to the machine shop that's doing the boring on the cylinders and have each cylinder matched to the piston per the Rotax specs. If you're machine shop is not familiar with this I wouldn't use them. There are specific bore and taper tolerances they need to follow and minor differences in each piston can result in each cylinder being slightly different to match the piston. That being said I've only had one case where the cylinders were bored differently. But I at least have them checked for match every time. If I remember correctly this is spelled out in the service manual.
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