71 Johnson 9.5 can't get rpms in gear

Just bought this old motor, 1971 Johnson 9.5 hp. Everything runs great and smooth, starts easily. In neutral it rev's to a high RPM. But in the water, in forward gear, can't get RPMS very high. Put it in neutral and it rev's up nicely. Put it in gear and very little. All the throttle linkage moves all the way like it's supposed to, but the engine just doesn't speed up much past idle speed. I can putter all the way across the lake, but turning the throttle has no effect. I'm pretty mechanically inclined but this is my first outboard engine. I'll take any ideas you guys have. This is my first post, but I've read a bunch of them and think it's great for you to share your knowledge and help others out. Thanks Big Zig

Re: 71 Johnson 9.5 can't get rpms in gear

most likely only running on one cylinder

Re: 71 Johnson 9.5 can't get rpms in gear

Agree with above but you should still get half speed (or close to it) with one cylinder. Get an adjustable spark tester and try both to see how strong the spark is. May end up having to service your carb. too. Also check your shear pin in you prop. let us know what you find. Best of luck. Rick.

Re: 71 Johnson 9.5 can't get rpms in gear

Check spark, and see if it runs w/cowling off. Sometimes those 9.5's have a torn upper shiftshaft boot, and exhaust displaces the oxygen going into carb when the cover's on..

Re: 71 Johnson 9.5 can't get rpms in gear

I just played with it in the driveway, thanks to a trashcan full of water. The knob that controls lean/rich was adjusted all the way in. Took it all the way out and then put it back in. It seems that there is a long distance for adjustment, say 1/2 inch or more. Adjusted it way out, and it may have cured the problem. Now it does rev while in drive. Does any of that sound normal? Hope I don't have a bad cylinder, cuz that prolly would mean a new (or used) motor. thanks for ya'lls input. Big Zig

Re: 71 Johnson 9.5 can't get rpms in gear

I think that has a fixed high speed jet. In which case the adjustment is most likely for idle. You probably don't have a bad cylinder just a bad coil, condenser or points. Have you checked spark on both cylinders and found a hot spark that will jump over a 1/4 of an inch?

Re: 71 Johnson 9.5 can't get rpms in gear

After you check for spark do a compression test.

Re: 71 Johnson 9.5 can't get rpms in gear

Solittle said:

After you check for spark do a compression test.

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RATS!!! Took it out yesterday, same thing, no RPM's in forward. That other adjustment thingy is for slow speed idle and of course has no effect on my prollem. The fly wheel pully will have to be removed with a pully-puller so I can get to the points and stuff. Is it normal for that pully to be on there that tight? I used to have a compression checker years ago and will look for it. If the compression is dead, is it time for last rites? Maybe I'll look for "overhaul in a can", that should work, right? Thanks ya'll for helping an newby to the bidness. If I can ever find someone with less smarts than me, I'll help them. Pay it forward. It's awful dry here in Texas, yesterday in church we prayed for Jesus to turn the wine back into water.

Re: 71 Johnson 9.5 can't get rpms in gear

Just checked compression. Just over 45 in both cylinders. Is that about right? Both plugs are Autolite 303. I'm gonna make me a flywheel puller in a day or so and will check the points, condenser etc. Any advice?
Thanks, Big Zig

Re: 71 Johnson 9.5 can't get rpms in gear

Yes its too low on that motor. "normal" should be 60-80 lbs compression. It could be just a blown head gasket or maybe your gauge isn`t accurate( check your gauge on something that is known to have good comp). I would start by taking off the head and check the gasket. If thats ok then pour some seafoam or trans fluid into each cyl and let soak for a few days. I would reuse (if possible) the old head gasket and recheck compression. No sense buying a new one if rings are shot.

Re: 71 Johnson 9.5 can't get rpms in gear

And get rid of the autolite plugs.

Re: 71 Johnson 9.5 can't get rpms in gear

OK. took off the head today. The gasket came off clean with no apparent breaches. Coated it with Gasket Seal and reinstalled it. got two new plugs, Champion J4C (original spec was J4J but this is the new crossover). Fired up the motor briefly and it rev'd nicely in gear, but it kind of did that before. tomorrow I'll take it to the lake and see if anything is better. All comments along the way are appreciated. I thought I knew a lot about mechanix but this is my first outboard motor and I kind of am on a mission here. To give up would make me feel defeated, but to spend the national debt on getting it going would also spell defeat. Does anybody think 45 lbs is too low PSI for an old engine? Hell, my compression guage is 40 years old also. I'm 58 but my compression is good. If this doesn't work, I'll tackle the flywheel removal and points/condenser and maybe the coil. Now's a good time to pipe in and tell me your thoughts. Thanks, Big Zig in Texas

Re: 71 Johnson 9.5 can't get rpms in gear

45 lbs compression is a little low, would like to see some where around 70-80. Maybe a good decarb would help. If it runs ok for you I would consider replacing the head gasket. Were you able to check the points and coils?

Re: 71 Johnson 9.5 can't get rpms in gear

Did you ever do a spark gap test and check your prop shear pin? What torque did you use on the head bolts? Rick.

Re: 71 Johnson 9.5 can't get rpms in gear

I'm taking it out today for a sea-trial, wish me luck. Later on I will borry a "harmonic balancer" and pull the flywheel and redo the points and condenser. Is there anything else I should do while in there. I'll get another head gasket tomorrow while in town. should I use any gasket goop or mount it all clean? I didn't torque the head bolts this time cuz I ain't got no torque wrench, (I only broke four of them off so that's not too bad.......no, just joking, gotta keep humor in life) but I can borry one when I replace with new gasket, prolly this weekend. I have tried to spin the prop and it is firmly attached to its shaft so I don't suspect that, after all it's RPM's I can't get. Could that somehow be involved? We got a camping spot right on the water for Labor Day so I hope we can get this thing going before then, or else I'll just have to paddle or mount a sail. (I do have a nice trolling motor but I haven't caught any trolls yet, how do you clean one?)
Thanks, ya'll, Big Zig

Re: 71 Johnson 9.5 can't get rpms in gear

I think I have it fixed now. Put in new plugs, the ones spec'd by johnson. The points were way too close, opened them up. Put the boat in and it opens up really well. It is only a 9.5 but it seems as though it is giving all it has. It even idled in gear really well as I trolled. Only once did it quit, and that scared me, until I noticed the gas line had disconnected just enough to cut off supply. Thanks for ya'll help. Big Zig