Sluggish and Surging

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htr2133

Seaman
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Jun 2, 2011
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74
I am hoping some of you master mechanics can help point me in the right direction. I have a 73 Johnson Seahorse 6hp. I took it out for the first run of the year Sat. It started fairly easily but doesn't seem to run as high as it should at full throttle. There are two issues I am noticing with the performance of the motor: 1. It is slow to accelerate, 2. once at full throttle it kind of surges slowly. It isn't missing really but more of a "lull" in rpms. In addition to these two as mentioned above, I don't think the motor is running at the rpm level that it should.

What should I check first?

BTW; the carb was rebuilt 3 years ago, no ethanol fuel has been ran since, i ran a full can of seafoam last summer in 3 gal of correct fuel mixture, I also put a half can of seafoam in the following mixtures last summer.

Thanks guys.
 
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huntingtheworld

Petty Officer 1st Class
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Jun 13, 2010
Messages
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Re: Sluggish and Surging

I have also seen the fuel stabilizers and treatments do bad things to a carburetor sitting up.
 
H

htr2133

Seaman
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Re: Sluggish and Surging

Thanks huntingtheworld; my grandfather who is a much better mechanic than I am suggested trying to replace the plugs first before having more carb work done on the motor. I also failed to mention; there is a slight bend in the prop. Could that cause the surge or limit rpms at full throttle?
 
H

htr2133

Seaman
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Messages
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Re: Sluggish and Surging

I tried to buy the plugs on iboats but it says out of stock? Am I going the right spot or is there another way to get the plugs from this site?
 
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boobie

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20,826
Re: Sluggish and Surging

You can also go to some local parts houses such as NAPA or a BRP Dlr.
 
nwcove

nwcove

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Re: Sluggish and Surging

nice motor you have. as your grandfather told you, start with the easy stuff....a new set of plugs per season isnt a bad idea anyway. ( save the old plugs in a zip loc baggy and keep them on board). did it run fine last season, or is it new to you?
 
H

htr2133

Seaman
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Re: Sluggish and Surging

nwcove said:
nice motor you have. as your grandfather told you, start with the easy stuff....a new set of plugs per season isnt a bad idea anyway. ( save the old plugs in a zip loc baggy and keep them on board). did it run fine last season, or is it new to you?
Click to expand...

great suggestion! no, it ran like this last season too, but I just thought it needed to be used more. So, I kept using it thinking the seafoam would eventually clean it all out and that it would start running well but it is running the same.
 
Tim Frank

Tim Frank

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Re: Sluggish and Surging

htr2133 said:
great suggestion! no, it ran like this last season too, but I just thought it needed to be used more. So, I kept using it thinking the seafoam would eventually clean it all out and that it would start running well but it is running the same.
Click to expand...

I have the '74 E'rude version.
When was the last time you cleaned and gapped the points?
 
H

htr2133

Seaman
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Re: Sluggish and Surging

Tim Frank said:
I have the '74 E'rude version.
When was the last time you cleaned and gapped the points?
Click to expand...


To my knowledge never.

I am guessing most places don't check that when you have the motor in for service if the motor starts fine and runs in the tank ok. That has been the case w this motor so I doubt it has ever been checked. Can I inspect the gapping and clean the points without getting into trouble and causing issues? The ignition system on these motors intimidates me.
 
O

OptsyEagle

Lieutenant
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Messages
1,365
Re: Sluggish and Surging

It is time to clean and gap the points. They do wear, over time, reducing the gap and changing the spark timing. This should be done every few years anyways. Also check to see if the carb is synchronized with the throttle cam. I am not completely familiar with the 6 Hp motor, but in my motors, this is done by ensuring that the roller on the carb touches the throttle cam at an exact mark that should be on the throttle cam. This ensures proper timing advance for the different RPM ranges of your motor.
 
nwcove

nwcove

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Re: Sluggish and Surging

htr2133 said:
To my knowledge never.

I am guessing most places don't check that when you have the motor in for service if the motor starts fine and runs in the tank ok. That has been the case w this motor so I doubt it has ever been checked. Can I inspect the gapping and clean the points without getting into trouble and causing issues? The ignition system on these motors intimidates me.
Click to expand...

if you are at all comfortable with basic hand tools, the universal magneto is as simple as it gets to work on. just do some homework ( top secret file at the beginning of this forum) and ask plenty of questions if you have to!! i would personally start with the carb if you arent 100% sure when it had its last cleaning and kit. if you go the carb first route.....plz ask about the recoil situation....thats the part on those motors that makes me cringe!! lol
 
H

htr2133

Seaman
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Messages
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Re: Sluggish and Surging

thanks guys; that is very helpful. The carb was gone through professionally 3 summers ago. No ethanol fuel since either. I think the carb should be good. I will change the plugs first and clean, throttle timing, and inspect the points and gap since you guys are saying that should be checked anyway. If that doesn't work; then I'll look to the carb.
 
Tim Frank

Tim Frank

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Re: Sluggish and Surging

Depending on your comfort level with ignition systems, you can definitely just clean and gap the points. (make sure that you clean them well if you do. Info to assist is in the Top secret files)
If this is at all a big step for you, consider replacing the points, and the condensors while you are under the flywheel. (2 of each)
 
H

htr2133

Seaman
Joined
Jun 2, 2011
Messages
74
Re: Sluggish and Surging

Tim Frank said:
Depending on your comfort level with ignition systems, you can definitely just clean and gap the points. (make sure that you clean them well if you do. Info to assist is in the Top secret files)
If this is at all a big step for you, consider replacing the points, and the condensors while you are under the flywheel. (2 of each)
Click to expand...

Really? Where do you suggest I buy the parts? I've read a lot on this now and a common theme is that the replacement parts are not as good as the original.
 
nwcove

nwcove

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Re: Sluggish and Surging

any brp dealer should have them in stock as oe. as you mention, the aftermarket stuff isnt as good and not much of a savings. you can get oe parts right here on iboats.
 
H

htr2133

Seaman
Joined
Jun 2, 2011
Messages
74
Re: Sluggish and Surging

nwcove said:
any brp dealer should have them in stock as oe. as you mention, the aftermarket stuff isnt as good and not much of a savings. you can get oe parts right here on iboats.
Click to expand...

I just clicked on the johnson parts link at the top of the page and it says the manufacturer is Sierra. Is that what you are talking about?
 
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