1998 Nissan 8 hp (NS8B) restrictor plate

[R R Jones]

I'm trying to improve the performance of my 8 hp Nissan. I've been told removing a restictor plate can help the engine perform like a 15 hp outboard. If this is true, need to know where I can get information on how to do it. Once it is removed will the engine require tuning. The engine runs great and starts every time. Just would like a little bit more HP. Has anyone experienced problems after the restrictor has been removed. Thanks

 

[TOHATSU GURU]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

If this is an 8B you can turn it into a 9.8 by changing a couple of parts in the carb, but that's the only increase this engine is capable of. I'll look up the part numbers and post them on Monday.

 

[TOHATSU GURU]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

You will need the following three carb parts to turn the 8 into a 9.8:<br /><br />3K9032520M Main nozzle<br />3K9032510M Main jet<br />3K9032540M Slow jet

 

[buckeye_sean]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

Elvin, I had the same question concerning my NS 9.9B2. I noticed in the manual that everuthing was identical in the 9.9, 12 and 15hp - (the 18hp has a bigger bore) I assume the difference in the first three relates in the carb? If you have a moment, could you let me know what is necessary to take my 9.9 to a 15hp?

 

[TOHATSU GURU]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

The only difference is the throttle cam that attaches underneath the coil plate. It is part number 364637180M and costs around $5.00. It is held on with two bolts and you do not need to take anything off of the engine in order to change it out. You will have to pop the carb link arm loose, but it snaps back into place. Thats the only difference, all the other parts are the same.

 

[buckeye_sean]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

Thanks Elvin!<br /><br />I'll be contacting you soon, hopefully you can get those pretty readily?

 

[R R Jones]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

Thanks Elvin, I guess 9.8 is better than nothing. Appreciate your help.<br />Bob

 

[Curtisvette]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

If this is an 8B you can turn it into a 9.8 by changing a couple of parts in the carb, but that's the only increase this engine is capable of. I'll look up the part numbers and post them on Monday.

Hi,
I ran across your tip on the above enginne and I to have a NB8B but a 2002 model can I also use the same parts to upgrade to a 9.8 HP?

Thanks

 

[SJ~brett]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

You will need the following three carb parts to turn the 8 into a 9.8:<br /><br />3K9032520M Main nozzle<br />3K9032510M Main jet<br />3K9032540M Slow jet

i hope these part numbers still work, thanks!

 

[TOHATSU GURU]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

No, it will not work. Your engine has a different block.

 

[SteveInMD]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

I have a 1994 NS8B (serial number 3B2-1 55659). Can I use the part numbers above to make it a 9.8?

 

[TOHATSU GURU]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

Yes and no. If your engine was brand new you could do it without a problem. But, your engine is probably a little worn now. While you will get the boost in hp you may also tend to foul out your spark plugs as you will be sending a little more fuel back there than it can handle.

 

[SteveInMD]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

It doesn't sound like it's worth it. Thanks.

 

[Todd RT]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

Yes and no. If your engine was brand new you could do it without a problem. But, your engine is probably a little worn now. While you will get the boost in hp you may also tend to foul out your spark plugs as you will be sending a little more fuel back there than it can handle.

So I guess my 1992 NS8B would not be worth upgrading either, huh? It's doens't have too much use on it.

 

[TOHATSU GURU]

Re: 1998 Nissan 8 hp (NS8B) restrictor plate

I wouldn't do it. A fresh new engine could handle the extra fuel. A 17 year old engine would tend to drown.