How would I know if the main engine bearings are going out on a 1997 60 hp 2 stroke

[Pacific Fisher]

Motor runs fine at low rpm but when above 3,000 it sounds and runs rough.
I have 120 pounds compression in all 3 cylinder and plugs are new and look perfect.. No water in very fresh fuel (emptied large water separating filter in glass jar).
The motor sounds a little loud mechanically at the higher rpm. I am wondering if a main bearing is going out. How can I tell.

Thanks

[robert graham]

2 stroke outboard motors(especially older ones) tend to make rattling, whirring, clicking sounds and it may well be that your imagination and just a touch of paranoia regarding your motor is creeping into your thoughts. Could be a bit of piston slap or other?....good luck!

[Pacific Fisher]

It is not fuel related as I swapped in a spare fuel pump.
I am going to replace the head and exhaust gaskets and consider it maintenance.
If that does not solve the problem, I will pursue electrical/ignition problem.

[Pacific Fisher]

Pulled the cylinder head off today and ordered heads gasket.
Dropped the head off at my machinist buddy to check for warpage and very lightly clean up surface. There may have been a slight sign of leakage at the bottom of #3 where one of the head bolts showed signs of water getting to it. Nursed that bolt out with the help of some good ZEP penetrating oil.
Piece of cake to pull the cylinder head off. Bores looked perfect. I could still see crosshatch from cylinder boring. I bought this boat used and the engine has 800 hours, maybe it was rebuilt at one time.

Anyhow, I should have the gaskets and head back on Monday. I will bolt it on, fire up and report on results.

Thanks for the responses.

[ausnoelm]

I think you are doing a hit and miss approach, before you start pulling anything to bits, you need to do some very basic trouble shooting, suspecting bearings, replacing fuel pumps, now head gaskets, you are going in all directions! truth be, you need a carby rebuild.

[Pacific Fisher]

I think you are doing a hit and miss approach, before you start pulling anything to bits, you need to do some very basic trouble shooting, suspecting bearings, replacing fuel pumps, now head gaskets, you are going in all directions! truth be, you need a carby rebuild.

I have been doing some basic troubleshooting in a number of directions. I had a spare fuel pump, so that took five minutes to change and verify it was not the problem.
Compression check (120 in all cylinders). The head gasket is not expensive and the head was extremely easy to pull. I have heard a number of reports about this engine commonly developing a head gasket leak between #2 and #3. So this allowed me to see the condition of the pistons and cylinder walls (excellent) and stay ahead of a future leak. Also the gasket did show some signs of water leakage.
When I bolt the head on and fire it up I will have eliminated a variable. If I have to go through the carbs I will. However I run and regularly change both a large water separating filter and the small filter on engine and keep very fresh gas in the tank.
Stay tuned.

[Pacific Fisher]

Got the head back from the machinist. He said it was warped.006 around cylinder #2. He cleaned it up on his mill. I bolted it on with new gaskets and the non copper never seize. It started up, idled and revved smoothly. Compression a little over 120 on all cylinders. I am back in the water for a total cost of $100.

Thanks for all the replies..

[robert graham]

Well, that's great!...hope it stays fixed for you!....good luck!