NS25C2 Revs Up and Down

[Sea Rider]

Sorry, can't help you with this one, only working with actual newer 25C3 & 30A4 models which has independent units.

Seems CD (first pic) is grounded on same unit (2 holes) second pic has a independent ground cable, if properly grounded to powerhead should work fine. The issue, will second one fit the space left by the first one ?

Data :

CD Output : 198-220 DVA
Exciter Coil : 100 DVA Min
Pulser Coil : 4.75-5.0 DVA
All measurements while Cranking.

Exciter Coil Resistance C2 : 200-300 Ohms
Pulser Coil Resistance : 30-46 Ohms
Wires must be Disconnected.

Seems that PC 13.5 V is way high if measured with the right DVA meter. Probably already altered ?

Happy Boating

 

[AGENT 37]

Update; New CD ignition unit did the trick! I replaced my broken fuel pump, got it running, tuned the carb, and she was starting with half a pull and purring like a rhinoceros. Then it started making racket. I immediately thought something gave in the lower unit because of how it sounded, but it turned out the flywheel nut came loose and the crank shaft key sheared. No damage done other than the key itself because I shut it down right away.

This Seloc shop manual is junk, the listed torque spec for the flywheel is 1.22-1.42 Nm/12-14 in.-lb/106-124ft.-lb.... no I didn't mistakenly type those numbers, that's what is printed. I reasoned that they got put in the wrong spot and I went ahead and tightened to 20 ft-lb when I put the flywheel back on.

I wasn't sure if the reverse threading nut was reason for the obviously low torque. I can, without a doubt, now say that 120 ft-lb would have probably been the right call though. Just one more example of why a good factory manual is crucial; I don't know if it is an issue of info getting messed up in translation from Japanese, you might think the Nm value might at least be correct though.

So, my I could use some feedback now. I've never really paid attention to flywheel/crankshaft keys, what are the chances this is a common size that I might find locally rather than paying quadruple the cost of the part for shipping and waiting another week or two to get the part?

My second question is what common props should be interchangeable with this gear case? It's a 10 spline prop shaft/hub. I already know that the 9x8 prop on this motor is not going to be a good match for my 13' 230lb rib.

I'm thinking Mercury parts might be my best bet, any other suggestions?

 

[pvanv]

Cool that the new CD did it. As is so often the case, it was impossible to definitively test it.

Yes, aftermarket manuals are useless.

We usually use a cordless impact gun, and "burp" the flywheel nut to about 12-14 Kg-m (110-124 in-lbs). Yes, too loose (or oil on the taper) is a problem. They go together dry, preferably cleaned with acetone to be sure (but you can use anti-seize on the threads if you feel strongly about it).

Yes, the woodruff keys are stock items.

Yes, all M25/30 props interchange. Tohatsu has a wide variety. You will want to tach test the motor to see what you have now, and then select a prop based on that WOT RPM.

 

[Sea Rider]

Which number is stamped on prop body ? If prop was factory delivered with OB should perform right on a light 13" footer Rib, anyway, will need to check that out with an induction tach and go from there maximizing a prop to suit your boating needs, loads, passengers.

Happy Boating

 

[AGENT 37]

I found the woodruff key that I needed at a local hardware store.

After trying to match puzzle pieces of props and thrust washers together at the local boat dealership I couldn't come up with a properly fitting combo between Mercury, Honda, or Yamaha hardware and this Nissan. The props fit but the thrust washers just didn't work out. I went to WM just to make sure they didn't have anything that would work for my motor before I put in an order online. Much to my amazement, I came across a Turning Point hub kit that fit and a compatible prop.... and the stuff was on sale for 20% off which made it even sweeter.

I put it together and dropped the boat in the water. Despite only having one choice available for a prop, a three-blade aluminumTurning Point 10-3/8" x 13P, I think it turned out to be the prop I needed. WIth a full 12 gallon tank of fuel, light payload, my four-year-old and I the hole shot feels respectable and up near WOT I hit 29.6kts on the GPS in the neighborhood of probably 5500RPM. I was very impressed with the performance of the prop. I did a little more fine tuning of the carb and linkage and now have myself a sweet running NS25C2 tuned up to 30HP.

Thanks to everybody for input. Hopefully my experience can help somebody else with their own project. I will try to post resistance values from my new CD ignition unit in the near future to provide something as a reference for testing.