Nissan NS8B Repairs or upgrades

[Mister R.]

I recently purchased a Nissan NS8B, that according to the serial number was manufactured in 1994. I have read several forum posts here (mostly from Tohatsu Guru) that this engine can be upgraded to a 9.8, by either re-jetting the carb, or completely re-carbing IF the engine is the right year of manufacture. My question is can I upgrade a 1994, and if so is it better to re-jet the existing carb (thoroughly cleaned of course) or to completely re-carb. Once that upgrade is complete I plan to install the full charging system (alternator and DC rectifier). Any concerns here?

Thanks in advance to all who help!

 

[pvanv]

Re: Nissan NS8B Repairs or upgrades

Year, irrelevant. Serial, critical, as most Two Stroke M/NS8 blocks were different from the M/NS9.8 blocks.

Re-Jet, no, never -- would cause massively rich running.

If possible, you would do the complete carb. What is your serial?

OTOH, the Four Stroke (NSF8) can be upgraded to NSF9.8 specs with a 9.8 carb.

 

[Mister R.]

Re: Nissan NS8B Repairs or upgrades

Serial number:

3b2-1458447

2 stroke. How about the alternator/rectifier upgrade, any issues here?

 

[Mister R.]

Re: Nissan NS8B Repairs or upgrades

Also,

This thread mentioned rejetting: http://forums.iboats.com/honda-tohatsu-nissan-outboards/nissan-ns8b-10-a-243315.html

I read the risk of running rich in other threads and am ok with re-carving, but the above one seemed to indicate re-jetting was ok if the block was in decent shape. What engine was this thread talking or was the fact that the engine wouldn't run a result of not re-carbing?

 

[Sea Rider]

Re: Nissan NS8B Repairs or upgrades

On models having same block and CC, usually you can't re jet due to carbs having thinner or wider fuel passages, that makes all the punch difference.-

Happy Boating

 

[pvanv]

Re: Nissan NS8B Repairs or upgrades

Serial number:
3b2-1458447
2 stroke. How about the alternator/rectifier upgrade, any issues here?

That's not a correct serial number. Drop the 3B2, then you should have 5 digits. You need 77531 or above. If so, then you can install the 3K9032000M CARBURETOR, 9.8 MF/EF MODEL $182.18, otherwise, you cannot.

Regardless, you can install 3B2061231M ALTERNATOR $48.65 and 346761602M RECTIFIER KIT 8B THRU 40C $108.96

 

[Mister R.]

Re: Nissan NS8B Repairs or upgrades

That's not a correct serial number. Drop the 3B2, then you should have 5 digits. You need 77531 or above. If so, then you can install the 3K9032000M CARBURETOR, 9.8 MF/EF MODEL $182.18, otherwise, you cannot.

Regardless, you can install 3B2061231M ALTERNATOR $48.65 and 346761602M RECTIFIER KIT 8B THRU 40C $108.96

Thanks for the help! That is the only thing that even comes close to looking like the serial number on the motor. Its on a small plate on the starboard side of the motor. Plate has the number 3b2-1 permanently inked on, and the number 458447 stamped on. Is this the model number then? If so where would I find the serial number?

 

[pvanv]

Re: Nissan NS8B Repairs or upgrades

The 458447 sounds right, but I would not expect 6 digits. I would contact Nissan Marine Outboards - Authorized Distributor Offering Boat Motor Products, Technical Information, & Dealer Locations for the U.S. & Canada." to ask them about the serial, and whether you can install the 9.8 carb.

 

[Mister R.]

Re: Nissan NS8B Repairs or upgrades

Thanks again! I just called nissan, looks like 58447 is the serial meaning its a no go for recarbing. Do I have any other options for squeezing a little more powers out? Will I really notice a difference btw the 8 and the 9.8? I have a lot of work to do to get thing where I want it, I'm just wondering if I should sell it and start over.

 

[Bronlonius]

Re: Nissan NS8B Repairs or upgrades

If you're looking for more power, The 9.9 2-strokes can easily be turned into a 15hp for very cheap.

Otherwise, how is your motor height? Using a jack plate to dial in motor height really made a difference for me.

 

[pvanv]

Re: Nissan NS8B Repairs or upgrades

Thanks again! I just called nissan, looks like 58447 is the serial meaning its a no go for recarbing. Do I have any other options for squeezing a little more powers out? Will I really notice a difference btw the 8 and the 9.8? I have a lot of work to do to get thing where I want it, I'm just wondering if I should sell it and start over.

You can't upgrade with the bigger carb, since you have the early block. Yes, 1.8 hp gain (22-1/2%) would be significant. But it's a moot point. If you need more hp, get a bigger motor...