evinrude 9.5 won't get up on plane

[fishinginwa]

hi, all.
i'm a newbie here. been reading the posts for a while now and finally have something i need some help with. i have a 9.5 that has new coils, plugs and wires. i adjusted the linkage so the carb now opens all the way. i've got this mounted on a 10' sylvan. she starts and runs smoothly but won't get up on plane. i checked the prop and there's no problem with a spun bushing. i've adjusted the motor angle from straight down to shallow running and still she won't get up on plane. this motor should be more than enough for the boat. any suggestions? any and all help would be appreciated. got to get her running so i can take my son out fishing. thanks in advance.

fishinginwa.

 

[tx1961whaler]

Re: evinrude 9.5 won't get up on plane

The may be too low in the water. Is the anti-ventilation plate even with the bottom of the boat?

 

[jay_merrill]

Re: evinrude 9.5 won't get up on plane

Your right, a 9.5 should plane that boat in a heartbeat. I used to have a dingy with a 5.5hp longshaft on it and it would easily plane, even though the cavitation plate was about 5 inches below the bottom.

I noticed that you didn't mention installing new points and condensors. I would go back and check the points and make sure that they are properly adjusted. Before you do that, you can check for spark with an inductive timing light. Also, is the spark advance synced with the carb?

The high speed jet in your carb is fixed, so adjustment isn't an issue. You didn't mention a carb rebuild though. A little bit of dirt in it is all it takes to foul the HS orifice. You can also try choking the motor while underway, to check for air leaks. If the motor wants to take off when you choke it, you are probably sucking air into the carb from somewhere other than the throat.

 

[tx1961whaler]

Re: evinrude 9.5 won't get up on plane

They usually don't start and run smoothly (I'm assuming all the way to WOT) with a messed up carb, but they will run nicely on only one cylinder. There will just be no power.....maybe time to run a spark test with a spark tester, if you haven't already. Compression is probably good, but it wouldn't hurt to check.

 

[Woodstock60]

Re: evinrude 9.5 won't get up on plane

Besides all that good info, proper weight distribution in the boat will make the difference. Move some weight to the bow. Ronnie

 

[nightstalker]

Re: evinrude 9.5 won't get up on plane

That motor should put that rig up on plane regardless of your weight distribution. She may only be running on one cylinder. I'd check that out first.
Nightstalker

 

[tashasdaddy]

Re: evinrude 9.5 won't get up on plane

just what do you have in the boat, besides the motor, how much do you weigh?

 

[Mandrake35]

Re: evinrude 9.5 won't get up on plane

Hi there! I have a 65 sportwin 9.5 and my friend has a Johnson 9.5......He has a little 10 springbok, and it'll just get on plane with the two of us in it. I should add that we're not little people LOL, maybe 450-500lbs between us.... so with just you that thing should plane unless you're Andre the Giant.

 

[fishinginwa]

Re: evinrude 9.5 won't get up on plane

Thanks for all of the helpful info. Sorry I didn't mention it earlier but everything electrical has been replaced with new. I've checked and the points and plugs are at spec. I just finished rebuilding the carb with no change in performance. BTW, clean as a whistle with no varnish build up at all. It was mentioned that maybe the cavitation plate is too low. I just measured and the transom length is 20" and the measurement between mounting clamps and the cavitation plate on the motor is 24". This puts the center of the shaft about 8" below the hull. Could this have been the problem all along? Thanks again and I appreciate the feedback.

 

[pcrussell50]

Re: evinrude 9.5 won't get up on plane

i'm new to boating as of summer '08, but not new to engines and engine theory, [i'm an amateur auto racer and build my own race engines], and i noticed that a lot of outboards, including one of mine are straight twins with a flat, 180deg crankshaft. i theorized, just like a previous poster, that if you one cylinder were dead, it might run exactly like it does with both, except it would be down on power. and i tried it on my twin, and sure enough, aside from being harder to start, it started and ran fine...on one cylinder, only it was down on power from where it normally was.

i can tell you that if you're sure about all the major ignition stuff, try one of the basics...the plugs. i can't tell you how many times i've seen a plug that is dropped on the shop floor, and either something breaks inside it and it becomes maddeningly intermittent, or it lands on it's electrode after being gapped, and the gap gets closed, and not noticed. just tossing out ideas. let us know how it goes.

-peter

 

[iwombat]

Re: evinrude 9.5 won't get up on plane

Sounds like it's riding too low. These motors need to be a little bit lower than their more modern counterparts in order to get water to the impeller. The anti-cavitation plate should ride about 1" below the bottom of the transom.

 

[fishinginwa]

Re: evinrude 9.5 won't get up on plane

Thanks everybody! I built a temporary transom extender, made a tiller extender, using PVC and a hose clamp, and moved my fat ***** to the middle seat and she plains like a champ. I was screaming across the water. And so was the boat! It looks like the motor was just sitting too low in the water to get her up on plane. Should have got a long shaft instead of an extra long shaft. Oh well, lesson learned. I'll be fine tuning the height of the extender and taking her out again for a test float. Thanks again. I'll definitely be back. This is a great forum. Tight lines! fishinginwa.

 

[reelfishin]

Re: evinrude 9.5 won't get up on plane

I run a 1972 Evinrude 9.5 on a 16' Starcraft and it planes out just fine with just my 300lb self sitting at the stern. It still planes out with a 250 lb passenger up front as well. My motor is in prime condition with 141 psi compression on both cylinders. It does really good on my 12' V hull too.

 

[LIGHTFOOT]

Re: evinrude 9.5 won't get up on plane

Have you tried running it with the engine cowl off. Exhaust leaks are a problem with that engine and it may be sucking exhaust gas instead of oxygen. Its worth a try!

 

[coolguy147]

Re: evinrude 9.5 won't get up on plane

how does it idle and start up? im thinking about compression

 

[coolguy147]

Re: evinrude 9.5 won't get up on plane

well acually u said ti starts and runs good so maybe it might be that its to low?