Opinions on Piston Wear

[Snowski]

Hello, I am new to this forum but not necessarily new to working on Rotax 2-stroke engines. This is my first stab at a Sea Doo engine and I need some opinions on piston wear that I found upon disassembling my 1997 SP motor. I also need help determining whether or not to reuse the flywheel that I pulled off.

Question on the pistons: I’ve not seen scoring exactly like this before, one especially deep groove that almost looks like someone put there intentionally on the pto side. There are also various smaller grooves but not nearly as deep in other spots and on the mag side. No grooves are present on the cylinder walls to match... Cylinders have minor wear typical of an engine this age, some cross hatching is still visible actually. Has anyone seen this type of piston wear before? If I put these back in, what is the likelihood of premature failure? Motor seemed to have good compression when torn apart although I did not compression test to confirm numbers. Trying to keep this to a budget build... Originally just tore down the motor to replace crank seals due to a catastrophic stator failure which ruined the seal on the mag side.

Question on the flywheel/magneto: When I pulled the flywheel off initially the stator came with it in pieces. Bolts were loose and bouncing around along with the windings. Should I reuse this flywheel and just grind down the high spots on the nubs? Do the magnets look to be in good enough shape that they won’t fly apart? A used flywheel can be sourced for relatively cheap so I don’t mind replacing if needed.

This ski has been coverted to premix if it has any bearing on the situation.

Thank you in advance for all help and suggestions! This is a great forum!

 

[POPPS]

Pistons look good, stator ring looks like junk....Is the stator coil intact?,,,I am assuming it is junk too.

 

[Snowski]

Thanks for the response! Nope, it’s completely gone. Out fell a pile of copper and metal when I pulled the flywheel off. Would you keep running the pistons? Crank bearings all feel good.

 

[mikidymac]

Rings look like they are getting worn due to the carbon showing below the bottom ring. I would have the pistons and cylinder measured by a machine shop and see if they are within spec before reinstalling them.