1997 evinrude 50 prop choice.

michaelj1978 · Apr 4, 2005

I have a 97 evinrude 50 on an 18foot flat bottom jon boat that has a full interior. I currenly have a 15'' prop on there now and the engine is revving way too high at WOT, around 7,000rpm. I only keep it at 5,500 max when I'm running around. I've tried a 17 aluminum on there and it still revs too high. Has anyone used a 19 and how much better will that make this boat run? (Tach has been checked and is correct)

Dhadley · Apr 4, 2005

Re: 1997 evinrude 50 prop choice.

That should be the 3 cylinder model, is that what you have? I agree with your thinking that the 19 would be a better deal on that boat (light and easy to push) but lets look at the tach. Make sure its fron OMC or BRP and is set on position 6. Check that out first and then we'll continue.

michaelj1978 · Apr 4, 2005

Re: 1997 evinrude 50 prop choice.

Tach is OMC and came with the boat. Setting is on 6. Motor is a 1995 2cyl (just pulled out the papers to double check). The guy at the prop shop said I must have a hell of a motor. I went ahead and ordered the 19 in stainless steel ($275 shipped) Too windy and I'm too sunburned from yesterday to get out, I'll try it out thurs or friday and see how it runs.

Silvertip · Apr 4, 2005

Re: 1997 evinrude 50 prop choice.

I believe the rev limiter on that engine is set at 6750. What speed are you running at 7000 rpm?

jfahlman · Apr 4, 2005

Re: 1997 evinrude 50 prop choice.

I'm rather new here and to boat repair but found a usefull link to props and prop selection from this site at the following link: http://www.boat-props.com/propellers/ Hopefully this will help you. Also, do you loose power at this high RPM? Just wondering if the hub is spun on the prop as this RPM seems rather high for a 50HP and that size of prop!

angus63 · Apr 4, 2005

Re: 1997 evinrude 50 prop choice.

I believe, if all the info is accurate, a league official will need a blood sample from that motor to make sure you're not violating the newly enforced policy

If she passes, wanna sell her?? Do you have another tach to verify your rpm?

Dhadley · Apr 4, 2005

Re: 1997 evinrude 50 prop choice.

Ah! Now you see how important the model number can be. If its indeed a 1995 50 hp 2 cylinder, the tach should be set on 5. Not 6. The good news is -- theres testing in your near future.

michaelj1978 · Apr 5, 2005

Re: 1997 evinrude 50 prop choice.

Last summer I had the tach out of the housing and set it from 4-6 to see if that made any difference. It's on 6 now, but I remember the difference between the settings was minimal as far as rpm@wot goes. I have the motor down as far as it will go and it still over revs. If I tilt it up any at all it just seems like it catches air, overrevs and the boat actually slows down. Even with the motor fully tilted down it will get past a certain point and start over revving. I don't have a speedometer on the boat, but it definately feels the fastest around 6,000rpm, anything over and it slows down. I'll report back this weekend.

Mark42 · Apr 5, 2005

Re: 1997 evinrude 50 prop choice.

First you need to make sure the tach setting is correct. I know most tach manufactures list the proper setting as 5, but depending on the model, it is either 5 or 6. If you have a voltage regulator then the setting is 6, if you have a recitfier, then the setting is 5. This applies to the early 90's Evinrude/Johnsons big twins, and probably your '95 also. I also believe, but am not 100% sure that the 6750 rpm rev limit is incorrect and a misprint in the manual. It is probably 5750, as the 40 and 48 hp models are limited to 5800. The manual says to run between 4500 and 5500. If it has aftermarket power packs, then who knows what or even if it has limits.

ob · Apr 5, 2005

Re: 1997 evinrude 50 prop choice.

Over revving a properly mounted 50 hp spinning a 15" prop on the back of a 18 ft john boat doesn't sound right.Particularly up to over 7 grand.As Dhadley has suspected,insure the tach is set properly and the engine is mounted correctly on transom.

G DANE · Apr 5, 2005

Re: 1997 evinrude 50 prop choice.

How high is your antiventilation plate sitting related to lowest point on transom of boat ?? It could sound like you have a 15" motor on a boat that demands 20" and the motor catches air (ventilates) when you get fully on plane. You should always be able to trim some up, with a limited speed and rmp gain as result.

G DANE · Apr 5, 2005

Re: 1997 evinrude 50 prop choice.

Edited - I misread your post, thought it was a 30 HP

walleyehed · Apr 5, 2005

Re: 1997 evinrude 50 prop choice.

Is there ANY equipment such as a transducer or anything mounted on the transom within 12" of center, either side??? My take on your explaination leads me to think you have a near-consistant ventilation problem, with a possible misleading Tach.

michaelj1978 · Apr 5, 2005

Re: 1997 evinrude 50 prop choice.

Transducer is mounted on the right side, I would say 15-20 inches away from the motor/center of the boat. Now that I think about it there is a dent underneath the boat where the bottom meets the transom on the left side about 12 inches from the middle of the boat. I guess it was from running over a log or something (we go way up in the creek arms and run over stumps and stuff all the time). I would say it's as deep of a dent the size of a baseball cut in half. Meaning if you cut the ball in half it would fit where the dent is and make the bottom of the boat flush again. Best description I can think of. I might try to get some pics of the motor and the boat up sometime soon.

walleyehed · Apr 5, 2005

Re: 1997 evinrude 50 prop choice.

That dent may be causing some problems...can you get to it to pound it out some???

michaelj1978 · Apr 6, 2005

Re: 1997 evinrude 50 prop choice.

Nope. I'd have to pull the batteries, fuel tank and rip up the rear floor board to get too it.

angus63 · Apr 6, 2005

Re: 1997 evinrude 50 prop choice.

Could you use a dent puller and patch?

michaelj1978 · Apr 6, 2005

Re: 1997 evinrude 50 prop choice.

I probably could, but the patch would probably get ripped off the first time out. We go up creeks and into a lot of brush and stumps to catch crappie. I'm going to give the 19pitch prop a try tomorrow or friday when it gets in and see if it will calm the motor down. I also just ordered a service manual and am going to redo the carbs because I'm having problems with it stalling when I shift into reverse or forward after startup or when it sits for too long between jumping from one spot to another.

walleyehed · Apr 6, 2005

Re: 1997 evinrude 50 prop choice.

The stalling sounds like it could be linc-N-sync problems. I don't think the prop is going to solve your problems...I don't believe what your tach says and I think you need to look deeper there, maybe compare to a shop tach. If you keep going up in pitch, you may actually be lugging the engine more and more....bad news. If you can't pound the dent out, you may have to clean and sand the area and patch with fiber-filled resin and sand smooth...it's tough stuff.

michaelj1978 · Apr 8, 2005

Re: 1997 evinrude 50 prop choice.

Got the prop in today. Service manual is on the way. I'm going to put the prop on saturday night and run it on the lake up the street from my house. I'm also going to take it to a different service shop than where I bought it for a second opinion after I run it. Going to get the oil changed, carbs cleaned and a full inspection/checkup.

1997 evinrude 50 prop choice.

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