1985 mercury black max xr2 150

[wantit2runright]

recently bought this motor checked fire on all cylinders good fire,checked compression 112 to 115 on all cylinders except bottom right it was 50 lbs. the guy helped me told me that i just needed to rebuild motor ,but i wanted to take it alittle father. the engine would not crank the original owner told me it was bad gas and the carbs to be cleaned.so i cleaned the tank and the lines added new gas got some carb cleaner sprayed let it soak ten min and tried it. it busted off then cut off .sprayed a few more times and it cranked but idled a little high. i let it run for 30 min reving up every so often well i noticed while running it had water coming out of the bottom right cynlinder the same cynlinder with low compression. so i figured the head gasket was blown i took spark plug out and it was milky. i took head off and found gasket was completely blown around that cylinder. i also noticed that that was pitting marks on head around just that cynlinder. i took the head and gasket to a local shop(very well notable) and ordered gasket. i asked mechanic about marks and he said that it was caused by aring getting loose and getting throughand hitting. he also told me may need to be overhauled but he said that may have been overhauled if that cylinder wall was smooth and free of marks or may have been sleeved. so when i got home it was as smooth as it could b and the piston looked cleaner than the rest.so the gaskets came in and they were not exactly same size on the opehing for the pistont.the old gaskts have a number 3.38 the gasket the computer calls for is 3.13which is alittle smaller opening. when i put the new gasket on ,the holes for the piston just barely clear ,while the old ones have 3\16 space arond cynlinder openings.coud this make any diffrence?could the motor have been rebuilt or bored out casing a little bigger head gasket than what the factory calls for?i went and ahead and put the new gasket on and checked compression warm and it was 90lbs on all 3 cylinders that seems a little low it idles high and still takes carb cleaner to start took to water goes in gear smooth give it gas starts to take off give more gas and it cuts off please help do ineed change gaskets/ why wont it plane off ? checked carbs and seemed as if it was dumping to much gas causeing it cut off please help thanks

 

[Faztbullet]

Re: 1985 mercury black max xr2 150

Stop ... dont do anything else untill you get a manual.

 

[latin monkey]

Re: 1985 mercury black max xr2 150

are you still getting water on the plugs?

 

[wantit2runright]

Re: 1985 mercury black max xr2 150

no,checked plugs,no water just a little bit of oil

 

[latin monkey]

Re: 1985 mercury black max xr2 150

are you saying the compression went down on the other two cylinders AFTER you put in the new gasket?

 

[ufm82]

Re: 1985 mercury black max xr2 150

This sounds like a real cluster...
1) Spraying carb cleaner ON the carbs does nothing for them other than making them look nice. The dirt is INSIDE the carbs and they will need to be pulled off and disassembled to be cleaned. Passages, galleys, jets, etc are all inside the bodies and the only way to clean them is to get at them directly. You can't do that by spraying anything on the outside.
2) If the head was pitted it could have been from water boiling inside the cylinder and removing some aluminum. If the head had impact marks from rings coming apart then you have other major issues. Running this engine with ring damage will destroy it. You said it has smooth cylinder walls- that means no scoring? No scuffing?
3) The head gasket part that extends into the bore will eventually come apart and could damage the cyliner- it's not just fiber in the gasket. You need to find the right one.
4) It won't plane because the carbs aren't allowing fuel to flow through- they need to be cleaned- See #1

UFM82

 

[latin monkey]

Re: 1985 mercury black max xr2 150

yes i agree with all above and you need to install the correct gasket

 

[wantit2runright]

Re: 1985 mercury black max xr2 150

i must have stated wrong the first time, the new gaskets have a 1/16 clearance around bore. the old gaskets had 3/16 clearance around bore.yes the compression went 90lbs on all cylinders but we checked immediately after running when it was checked the first time it was cold. yes it is impact marks on the head and the mechanic that told me that, said that the cylinder wall would have been tore up but it was very smooth and clean. he also stated that since it was smooth it may have been overhauled and the shade tree person who did it did not smooth the head out and left it like it was.i understand the carbs need to be rebuilt, iam trying to make sure either thew gaskets that were on it were wrong and the new ones are right i would not install gaskets if they were inside the bore opening please help thanks