Yamaha Saltwater Series 200 OX66 Compression

[AirQuinn]

I'm thinking of buying a boat with a 1999 Yamaha Saltwater Series 200 OX66 engine. I want to have a compression check performed but don't know what acceptable results should be.

Also, I'm told that this motor does not have an hour meter. Is that correct?

Any help would be greatly appreciated.

Thanks!

 

[robert graham]

Re: Yamaha Saltwater Series 200 OX66 Compression

The accepted rule of thumb regarding cylinder compressions is that each cylinder's reading should be within about 10% of other cylinders. The actual compression readings can/will vary with test and conditions, but readings in the 100-120 PSI range would be considered fairly normal. What you wouldn't want to read is most cylinders all about 100PSI and 1 or 2 in the 50-70 range, indicating weak cylinders, stuck rings, damaged cylinder walls, etc.....I don't know about retrieving the total operating hours on that motor, but if the compression readings are good and it runs good and the price is right, then go for it!....It would be hard for me to buy a motor without seeing it run on the boat and in the water under load....good luck!

 

[AirQuinn]

Re: Yamaha Saltwater Series 200 OX66 Compression

The accepted rule of thumb regarding cylinder compressions is that each cylinder's reading should be within about 10% of other cylinders. The actual compression readings can/will vary with test and conditions, but readings in the 100-120 PSI range would be considered fairly normal. What you wouldn't want to read is most cylinders all about 100PSI and 1 or 2 in the 50-70 range, indicating weak cylinders, stuck rings, damaged cylinder walls, etc.....I don't know about retrieving the total operating hours on that motor, but if the compression readings are good and it runs good and the price is right, then go for it!....It would be hard for me to buy a motor without seeing it run on the boat and in the water under load....good luck!

Thank you. This was very helpful. I've made an offer on the boat but contingent on compression test results and a sea trial.

Thanks again.