NS40C plugs

[MH Hawker]

I recently brought a NS40C back to life its 1988, and i have redone the fuel system and the PO added a new fuel pump and i rebuilt the carb, it wasnt idling befor and now it runs fine and idles fine, but i had to guess on the float setting and the pilot jet settings , the service manual was usless on that, and i pulled the plugs and was suprised to find them a bit dark, and this is only about 7 hours of running , i suspect the pilot jet screw isnt set right i set the float level and the pilot jet at 1 1/2 turns, any info would be apricated, the plugs are NGK B7HS-10 set to .40, factory spec, running 89 oct fuel

 

[Sea Rider]

Re: NS40C plugs

If it's a 2 strokes 2 cylinder engine, the pilot screw is just for adjustment idle/ralenti speed, carb has non adjustable fixed jets for other speed greater than idle, 1 1/2 turns is correct, plugs & plug gap ok, probably to much oil mix, plug fouling check 50:1 ratio.

Happy Boating

 

[pvanv]

Re: NS40C plugs

You need a Factory service manual, available from any dealer, including me.

 

[John_S]

Re: NS40C plugs

You need a Factory service manual, available from any dealer, including me.

MH,
Look under the Tohatsu engines in the link I sent. It has specific consoledated service info for the M40C which is the same as your NS40C. That info is specific to the early 40C's which have a combined CD box w/embedded coils. That info, either is not present in the latest version of the factory manual, or I just haven't found it yet. If you were using the link under the Nissan, it is a "combined" (selec/clmer type), but the specific data is for later models of the 40C.

FWIW: The latest Nissan/Tohatsu factory manual which combines a number of 1-2 cylinder engines is not as easy of a read compared to specific model Mercury/Mercruiser factory manuals I am familiar with. The specific pictures help us DIYers. For me, it is more of a help for my 18E than my early 40C. I wish I could have found the older factory manual that was just on the 40C.

Anyway, just my opinion on the manuals.

 

[TOHATSU GURU]

Re: NS40C plugs

John,

Send me an email

elvind@solutiononemaritime.com

 

[John_S]

Re: NS40C plugs

John,

Send me an email

elvind@solutiononemaritime.com

Will do, this evening.

 

[MH Hawker]

Re: NS40C plugs

i receved a clamp on inductive tachometer yesterday in prepration to find my WOT prop range and also take a closer look into the plug issue and i just finished running the motor on muffs in the yard the PO had the idle set to 1300 rpm insted of 1000, and the pilot screw was set 1/2 turn high, and that would explain the plug fowling , a to rich mixture with the idle set up to keep it running, now i expect it to do a bit better, i spend good bit of time at idle speed at nights moving from fishing spot to spot, and yes i have a factory service manual i got the fist week i owned the boat