can Compression be too high?

[Hdog412]

Hi everyone,

I just posted this, but I think I posted it in the wrong place (sorry first time posting). I am considering purchasing a 2000 Key Largo with a 2000 50 Hp Johnson. The guy did a compression test for me and it came up 160 on each cylinder. Is that too high, I was under the impression it should not be over 150. If anyone know please advise me.

Thanks

Regards

Harry

 

[robert graham]

Re: can Compression be too high?

I can't imagine that being a problem, and expect his high readings probably due to his compression tester or testing methods. Good Luck!

 

[Hdog412]

Re: can Compression be too high?

Thanks, I think we are getting a good deal, the boat seems to be in great shape, all the electronics work. He was asking $4500, but I have talked him down to $3900, he recommends rebuilding the carburetors (I haven't work on a carguretor for 17 years

 

[a70eliminator]

Re: can Compression be too high?

A shot of oil in the spark plug hole can make a scored cylinder show great compesssion.
Is there any peticular reason why he recommends rebuilding the carbs?

 

[nymack66]

Re: can Compression be too high?

Please please test ride this on the water, that compression is spooky for the lack of a better word. I learned the hard way. You don't have to ..Good luck ..Sales pitch for all use outboards you just have to "freshen up the carbs" don't fall for it ..It may all pan out ok but hey if he confident it working, he will have no problem with you asking to see how it runs on water. My rule is simple all Outboard runs well on muffs, on the lake is another !

 

[kenmyfam]

Re: can Compression be too high?

Hi everyone,

I just posted this, but I think I posted it in the wrong place (sorry first time posting). I am considering purchasing a 2000 Key Largo with a 2000 50 Hp Johnson. The guy did a compression test for me and it came up 160 on each cylinder. Is that too high, I was under the impression it should not be over 150. If anyone know please advise me.

Thanks

Regards

Harry

Compression testers can vary quite a bit. All within 10% of each other is important though.
Good 1 hour water test is the best thing you can do to verify performance though.

 

[kenmyfam]

Re: can Compression be too high?

Thanks, I think we are getting a good deal, the boat seems to be in great shape, all the electronics work. He was asking $4500, but I have talked him down to $3900, he recommends rebuilding the carburetors (I haven't work on a carguretor for 17 years

If that is all that it needs then ask him to do it before you test run it in the water. See what the response is.

 

[aesgator]

Re: can Compression be too high?

My first boat was one that went like this. Went there ran great on the muffs, compression test somehow looked good. Bought it, got home, put on the water, bogged down bad and ran an oil slick. One of the cylinders had a hole worn through it when we broke it down. Not saying this is your situation, but I wouldn't buy a boat with out a test run ever again.

 

[JB]

Re: can Compression be too high?

Psi that high suggests to me dishonest manipulation of the compression test.

I would require an on-the-water demo or pass.

 

[Hdog412]

Re: can Compression be too high?

You guys are definitely giving me a lot to thing about and I appreciate everyone's input. I will definitely take it for a test run.

 

[Hdog412]

Re: can Compression be too high?

A shot of oil in the spark plug hole can make a scored cylinder show great compesssion.
Is there any peticular reason why he recommends rebuilding the carbs?

He told me re recommends the carb rebuild because it has been sitting for 20 months

 

[a70eliminator]

Re: can Compression be too high?

Good reason, it probably won't even run if sat with fuel in bowl that long.

 

[Hdog412]

Re: can Compression be too high?

First I would like to thank everyone for their input, I am really glad to have come across this site.

He didn't want to run it with the gas in the boat fuel tank (since it had been sitting so long) so we started it with the 6 gal tank I have for my aluminum boat. It had a difficult time to start at first, but once in started it ran OK (a little rich with a lot of oil in the fuel mix) As people mentioned earlier in the posts it seems to run fine on the muffs, but I Think it needs to be test run.

I also notice some hydraulic fluid leaking from the trim and tilt pump he said that he thinks there is air in it and it needs to be bled to release the air bubbles. I just don't want to jump the gun but down here in FL a decent boat sells quick and I have seen similar boats (in a lot worse condition) sell for more.

 

[Hdog412]

Re: can Compression be too high?

He has offered to rebuild the carbs (with my help) if it would help seal the deal. The guy seems pretty up front about what the boats issues are. He said that he would be willing to do it this weekend, he already had the rebuild kits (he had planned on doing it for himself) and also purchased some carbon reeds to install. I guess it wouldn't be bad for me to get a refresher in a carb rebuild (man I am getting old)