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1967 johnson 6hp low compresson

R

RALPH NOELL

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" HI I have a 6hp johnson. I w

" HI I have a 6hp johnson. I was having a hard time starting it. I put everythink in it. I had the cab. done. I should of ran a compresson test. I did today. 60-60. I put oil in and checked it again,same. where do i go now. New rings. Is there anythink else i can do. "
 
"Ralph.... The fiber portion o

"Ralph.... The fiber portion of the ignition points that rides against the cam should be aligned with the flywheel/crankshaft key when setting the points. Points set at .020 when in that position. Your compression sounds okay.

The spark, with the s/plugs removed, should jump a 1/4" gap on that engine. If it does not, find out why. If you have compression and the proper spark, the problem would have to be fuel related.

Possibly you have overlooked the fixed brass high speed jet that is located in the bottom center of the float bowl. Fuel must flow through that jet before it can get to any other fuel passage. It can be cleaned with a small solid piece of wire.

The proper adjustment of the carburetor is as follows.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

Joe
"
 
" Sixty pounds of compression

" Sixty pounds of compression as awfully low. Check the compression again using a different compression gauge. If it is still low, but the two cylinders are reading the same, you may need a head gasket. Get a new head gasket, then pull the cylinder head checking the original gasket for leakage and look at the cylinder walls for scoring. Be sure that the gasket sufaces are thoroughly cleaned before installing the new head gasket. Using a torque wrench on the head bolts would be nice. "
 
" Sixty pounds is definately l

" Sixty pounds is definately low, I would expect to see 90, 80 minimum. I have to agree w/Bubba. "
 
HI still working on this engi

HI still working on this engine. I took the cab of today. I have checked everything that i have got off this page.I found 1 nut loose on the carb. when i took it off. I hope that was part off the problem. THANKS for all the help. will let you know if i find the problem.
 
On a 67 johnson the differenc

On a 67 johnson the difference between 75 compression and 50 is that the motor takes longer to acheive full rpm 75 jumps to rpm while 50 winds up to full rpm. The motor will start and idle just fine either way. You do not have a head gasket or a compression problem look elsware.
 
" ANOTHER COMPRESSION ISSUE...

" ANOTHER COMPRESSION ISSUE...

I'm looking at (buying) an '82 or '83 (current owner doesn't seem to know which) Evinrude 6HP outboard. He bought it used from another person and has no manual or documentation. It starts OK, seems to run quietly, looks in OK condition compared to some online pics I've seen, goes into forward and reverse and the owner seems genuine enough.

He seemed willing to take it out for a trial in the local harbor but there's snow on the ground here in NY so testing on the water is impractical for now.

One thing concerns me. When the motor was running in the tank (not in gear) it seemed slow to build revs. It was as if it had a heavy flywheel or possibly a measure of fuel starvation (dirty filter?). It was not very pronounced and didn't mis-fire or anything, just a little more sluggish than I expected. It struck me as odd since all 2 strokes (motorcycles) I've used in the past rev pretty freely.

It ran fine in forward and reverse in the tank, BTW.

The top cylinder showed around 75psi with the bottom one a little lower at around 72psi. From research I understood compression should be in the region of 120psi. If so we have a serious discrepancy here.

I made some errors when testing compression: -
1)Leaving a spark plug in one pot while testing the other - would that affect readings in a major way?
2) Not disconnecting and grounding the high voltage wire.
3) We didn't pre-run the engine for a full 10 minutes.
These steps were all suggested in the compression gauge manual, however, we were in his basement with no vent, at night and he was in a hurry to go somewhere.

Any idea why the compression should be so low? If it weren't for this I would probably already have bought it 'cos it seems like a good buy. "
 
" HI chriss I,m just getting i

" HI chriss I,m just getting in to boat motors. the compression sounds good. If the price is right buy it. RALPH "
 
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