hey guys.. this is my very first post on my very first website. I have just purchased my first bass boat (1997 sprint 207 pro tournament) and it has a 200 evinrude vindicator on the back. The boat has a 25p 4 blade renegade prop and struggles to get on plane. Top end is barely 50 MPH. What's the problem here ? my WOT rpm's are about 41-4200. Props are so expensive and i don't want to spend 500.00 on a new prop and have it be worse. 

 

happy to be a part of the group here ! 

 

- dev

That motor should spin that prop better than that. Hopefully one of the prop/motor guys on here has an idea what it may be but I wouldn't be running it anymore until you figure it out what it is. 

Vindicator should be running between 5K -6K rpm at W.O.T.  Need to figure why RPM's are low.

Probably worth a shop check.  Likely you will save $$ in the long run.

Classic symptom of being down on one  cylinder. 

Also a classic example of why I say it's dumber than dirt to buy one without testing it or having it checked by a qualified mechanic.

i had it checked by a professional before i bought the boat. Compression was 110 on 4 of the cylinders 105 on one and 95 on the other. From what the mechanic said and what i've known those are decent compression numbers. I was told anymore than 15 PSI difference means that i have a problem coming.

I would be leary of that 95 psi . I would have the compression tested again and check that cylinder. Ive always gone by within 10psi on all cylinders. 15 difference on only 1 would have been a big red flag. Did you test drive the boat prior to buying? you need to have the boat looked at. Could be something minor but if it could also lead to a blown powerhead and you'll be SOL.

I'd question if it is being trimmed propely, both at take-off and once planed out.  If it's not trimmed all the way under, it will struggle to get up and if left in the same position,  will not achieve max RPM.

 

My stepdad was around boats all his life and never understood trimming.  He said "all the way down to run and all the way up to trail."  He never could figure why the boat always ran better for me than him!

all of those compression numbers are low, they should be in the 150's. anything under 100 and you will have power issues. the general rule is all cylinders within 10 PERCENT of each other but 10psi is normally the range. only early 80's and below outboards ran compression below 100psi because they had lower compression ratio's.

the only way to know for sure what your engine should run is to find the comp ratio. for example I had a 79 25hp Johnson with a comp ratio of 6 to 1. This compression ratio means that the outboard is designed to compress the fuel/air mixture at 6  times atmospheric pressure so new it should have around 88 psi compression

River basser, NO WAY would that m ever show those kind of numbers in stock configuration.  135psi is about the max you can run on fresh, 87 octane gas.  125-128 is about the max I've seen on a stock carbureted motor and that's on the 225HO.  I only run 155 psi on my 325hp modified motor on 93 octane and will still pop a piston if I get some bad gas at the pump.

As for a max number, that's hard to tell because of other variables, the main thing is the difference between the highest and lowest cylinder should be no more than 5% on a good motor, and that should be after being about 15 minutes to warm it up.  Cold  motors lie bigtime on compression numbers.

Dev, I hate to say this, but sounds like you took it to the wrong expert.  95 is not good on that one, and I hope it was not #2 or #4 cylinder that was low.

take it to the lake and do a plug dump and see how the plugs look.  Run at WOT for about 5 minutes down the lake and shut the ignition off while still holding it wot.  Then pull the plugs.  None should be no darker than a brown paper bag.

You may be correct on his being around 130 since I don't know  his ratio but my 1991 120hp 2 stroke carbeurated has 155 as the highest and 148 psi on the lowest. 

If that's an OMC I would suggest you get a new gauge.

I was not suggesting it was even near 130

2 minutes ago, Way2slow said:

If that's an OMC I would suggest you get a new gauge.

Idk what that stands for but I don't know why it's so hard to believe. My weed eater has 100psi compression lol

Outboard Marine Corp (OMC) made Johnsons and Evinrudes until going belly up in 2000.

The constant hassles of dealing with those like you that think they know and don't is why I've almost quite posting on here.

ya'll have fun.

7 minutes ago, Way2slow said:

Outboard Marine Corp (OMC) made Johnsons and Evinrudes until going belly up in 2000.

The constant hassles of dealing with those like you that think they know and don't is why I've almost quite posting on here.

ya'll have fun.

Please don't do that ~

I am certain that I'm not the only one who appreciates is very grateful for your willingness to share your expertise & experience.

A-Jay

44 minutes ago, Way2slow said:

Outboard Marine Corp (OMC) made Johnsons and Evinrudes until going belly up in 2000.

The constant hassles of dealing with those like you that think they know and don't is why I've almost quite posting on here.

ya'll have fun.

I wasn't tryin to offend man or claim that I knew more, as I said in an earlier post you could be correct on his particular outboard because I didn't know, but I shared my knowledge on compression values and how they are based on the particular engines ratio. This is from my experiance as a diesel mechanic for the last 7 years. And you are correct my outboard is a Force which may be why mine are higher than OMC.  Sorry if it came off the wrong way

7 hours ago, A-Jay said:

Please don't do that ~

I am certain that I'm not the only one who appreciates is very grateful for your willingness to share your expertise & experience.

A-Jay

No you definately are not the only one.