Johnson 9.5hp compression (1968 or '69 I think)

[joblo33]

I'm taking a look at my friend's 9.5 Johnson for him and I was wondering what kind of compreesion I should be expecting. It's a 2cyl model MQ-14E, which I cross-referenced as either '68 or '69. Compression is at 87 and 89 psi. The motor was dropped in the lake while running by a previous owner, so I expect some wear would have occured.

 

[Paul Moir]

Re: Johnson 9.5hp compression (1968 or '69 I think)

That doesn't sound out of line to me for a 9.5 of that age. It won't be making all it's power, but it should start and run fine. Decarbing the engine might bring the numbers up a bit, but like most outboards, the 9.5 was a fairly low 'compression' engine to begin with.<br /><br />OMC never published any sort of spec for compression other than to say if it was even, it was good. 87 and 89 are well below the 10% varience they allowed. It was a wise decision, in my opinion, since testing methods and compression testers vary so much. If you search this site for '9.5 compression' you'll find what others have measured.<br /><br />Bent or damaged conrods or bearings is what I would be worried about if it had been submerged while running. Is there any sort of problem?<br /><br />Oh, and welcome to Iboats!

 

[wayne h]

Re: Johnson 9.5hp compression (1968 or '69 I think)

that reading sounds good to me i have a 9.5 with 70 and 72 on the cylinders and she runs like a top. as for in the water paul is right about rust on the rods and bearings but i have also took a chance with a motor that was dropped in a lake all i did was cleaned the points changed the waterpump and up my premix for a few tank fulls and took her for a run never had any problems with she at all. i dont understand why people dont use safty cables on these motors i hear alot of people losing motors in the water. not only will a peice of steel braided cable and a few clamps stop her from dumping in the water but it will make theft that much harder for a theif.

 

[joblo33]

Re: Johnson 9.5hp compression (1968 or '69 I think)

Thanks for the suggestions. Ya, I use a cable on all my motors, the guy who lost this one obviously didn't, he had to send a diver for it. The rods and everything should be fine, he said the previous owner opened up the block after recovering it. It's running pretty badly, but I think it's a carb problem, so I'm gonna open up the carb tonight. It almost sounds like it's getting no air in the mix every few seconds. It also stalls when shifting from neutral to forwards, which also sounds like a carb problem.

 

[joblo33]

Re: Johnson 9.5hp compression (1968 or '69 I think)

I took one look at the carb and realized that the choke assembly was getting hung up at half choke and was never opening right up, thus the bad mixture. bent a bar back in shape and now it runs a whole lot better.

 

[Benruger1]

Re: Johnson 9.5hp compression (1968 or '69 I think)

I have the same motor, took it out once ran great. Now i cant get it to crank. Sprayed carb cleaner and it would crank long enough to burn the carb cleaner off. I changed the plugs, still no luck. Any suggestions?

 

[ezeke]

Re: Johnson 9.5hp compression (1968 or '69 I think)

To Benruger1. I think that you will get better help if you start your own thread.

The carburetor probably needs cleaning.

The high speed jet lies behind the drain plug at the bottom of the float bowl where it gets clogged by anything that sinks, plus the gel that forms from old fuel mix when the motor sits awhile.

Try to find a factory service manual on ebay. Any 9.5 johnson or evinrude will work, but the 1973 service manuals are the most complete at the end of the series.

 

[jbjennings]

Re: Johnson 9.5hp compression (1968 or '69 I think)

I just checked a '68 9.5hp and it had about 80lbs. on both cylinders and it idled great, cranked with one compression stroke.
I think you're sitting pretty on compression with those numbers.
JBJ