Nissan ns18c2 cuts out when you open throttle!!

Rodman738

Seaman Apprentice
Joined
Jul 7, 2017
Messages
40
i purchased this Nissan 18 hp 2 stroke a year ago. I was going to use it on a 10 hp limit lake.the motor has always started and idles well. When I go to open the throttle it cuts out for a while then slowly starts to come alive. I have a 9.9 Nissan that I have swapped cd units ignition coil. Have cleaned the carb. Would love to get this motor running good my 9.9 actually runs better than the 18. Could it be a timing issue ? Any help would be appreciated this motor is going on the market soon if I can't get it to run any better.
 

Rodman738

Seaman Apprentice
Joined
Jul 7, 2017
Messages
40
Great article on timing! I checked my timing and it was actually pretty close. Had to adjust my stops slightly. Butterfly was 98% open adjusted it slightly.
Motor is on a14 ft aluminum boat. Me and my wife and extra 10 hp motor it goes 21 mph. My 9.9 Nissan 2 stroke is at the same speed! I was really hoping for better performance out of it. Will probably try a few prop changes and see if that helps. Prop is 9 1/4 x 10 presently will try the 8.5 off the 9.9 and see how that works.
 

Rodman738

Seaman Apprentice
Joined
Jul 7, 2017
Messages
40
Tried the motor out tonight still cuts out when you go to open throttle! Will eventually come to life but definitely hesitates or almost misses till rpm get high enough. Definitely not a smooth transition to full speed. Still 21 mph with the 8.5 prop.
Anyone ever had this problem? Not sure what to try next!!
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Once the timing plate mark has been correctly adjusted to 25 deg, full throttle and check that the cam is not over actuating hard agains the white roller. Once the while roller is at the high side of the cam you need to be able to spin the roller with your fingers. If too tight hold the throttle to max, release the nut that holds the vertical rod in place, hold the pawl plate fully down, and raise the roller body extreme as shown with finger till lightly restes on the cam, once there secure the nut tight.

If the cam over actuates the roller will end wearing all the plastic bits of the throttle system specially when going back and forth, say from 3/4 to full grip on constant basis. Check the pics for clarification...

All portable Tohatsu motors with props factory delivered with are way over proped, a 8.5 pitch should increase wot rpm much better, but would be ideal to count with an induction tach to check achieved max wot revs increase to check if at least runs at middle wot rpm range which is 4500 rpm. The wot rpm range for that motor is : 5200-5800.

The hesitation issue, bogging whatever the motor is experiencing is at 1/2 to full grip ? if so, this issue could be due to the fuel line is sucking air at higher rpm and motor behaving as such. What is the condition of both connector's o'rings, are dried, worn ? Can you test said motor with another fuel line swapped from a motor that works with 0 issues running strong to discard it's a fuel line related issue ?

Happy Boating
 

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