Nissan 5hp is slipping at higher speed

[livemusic]

I bought a used Nissan 5hp outboard. When I increase the throttle past about half speed, I can hear the motor revving higher but the boat doesn't go faster, or if it does, not much. It's like it is 'slipping.'
Forty years ago, I owned a Mercury 9.9 and it had some kind of rubber clutch gizmo under the propeller. I used it for duck hunting and the sand from the river would wear it out and I could replace it and it would be good for another year or two. Do you think it is something like this or could it be the transmission or whatever it has in there? LOL, I know very little about an outboard.

Also, how do I find out what year and model this outboard is?

Lastly, am I supposed to add oil to the lower unit? What maintenance do I need to do to a 5 horse?

 

[pvanv]

The year of manufacture is irrelevant for servicing Tohatsu/Nissan outboards -- you want the precise model/serial from the motor tag "sticker". The model will be in the format NS5B (for a 2-stroke 5 hp Nissan) or NSF5B (for a 4-stroker). The A,B,C,D, etc., on the end is the model revision.

All current Tohatsu/Nissan OB's above 3.5 hp use a prop with a rubber hub in it. You can buy a replacement prop to get rid of a slipping hub. It's too labor-intensive to replace the hub on these small props.

Oils (both LU and crankcase) should be changed every 50 hours or annually, whichever come first.

See your owner's manual at http://www.nissanmarine.com/tech_talk/owners_manuals.html for servicing and operating information. A full tutorial on changing the LU lube is at http://www.nissanmarine.com/tech_talk/oil_change.html

 

[livemusic]

Thanks for replying, Paul. Today, I ran it again and it ran like a top. I am thinking that maybe there was moss from the moss-filled lake on the lower unit. Thinking back, that is exactly what it acted like. I guess it threw me that it happened on two trips. It seems odd that it would happen twice if it was just moss, but, it's possible. Okay, I will get the manual and change oil and hope for the best on the slipping.

 

[livemusic]

Darn, I have looked this motor over and cannot find any kind of stamp or decal on what model it is. I do see a rectangular area just behind the gear shift lever that could possibly be where a sticker was glued on? How can I tell which model this is?

It looks like this one -- http://smalloutboards.com/n501.htm -- and it says it is a NS5B. My opinion from running this motor is that it is a 2-stroke. I also note that in that image, there IS a sticker behind the gear shift lever.

 

[pvanv]

The pictured motor is an NS5B, which is a 50:1 2-stroke. That means you need to mix TCW-3 oil with the gas at a ratio of one pint per 6 gallons. Production ended around 2003. IIRC, the serial plate was usually on the flat section of the transom clamp. If it is a 5B, the carburetor is on the front of the motor, if on the starboard side, it's a 4-stroke. There should also have been an EPA compliance sticker.

 

[livemusic]

The motor is running fine now. The carburetor is on front, it's an NS5B. Can you tell me... does this motor require ethanol-free gas? What to do if answer is yes, and I can't find ethanol-free? Thanks for help.

 

[Sea Rider]

Use any free or E10 fuel, better is higher octane than regular.

Happy Boating

 

[pvanv]

Non E is best. Freshness counts. There is usually non-E available either in marinas or as high-test at the street pumps, but it may be hard to find. Always run the carb out at the end of the day to reduce varnishing.

 

[livemusic]

Non E is best. Freshness counts. There is usually non-E available either in marinas or as high-test at the street pumps, but it may be hard to find. Always run the carb out at the end of the day to reduce varnishing.

How do you run the carb out since the gas tank is built in to the top of the motor? If it had a gas tank like the old days, I could just disconnect the gas tank and run it out. Is there a switch on there?

 

[Sea Rider]

There's a lever in middle fuel ****, flush engine after earch outing and while it's being flushed close lever untill engine drops dead. Don't forget than in upper fuel **** there's a small mesh filter which needs to be cleaned from time to time specially if using not well filtered fuels. This will assure best engine performance along new prop.

Happy Boating