Nissan 6 HP 4 cycles

[c_amos]

Got the motor in the other day. Nicely packaged, looks to be pretty good gear.

Couple of interesting things I noticed. First, the fuel connector is not the same on the tank and the motor. The motor connector is the 'nissan' connector, kinda like the OMC, but not quite, nor does the Yamaha connector fit (although it is close). The tank connector looks exactly like the older (round) OMC type connectors... but I bet it is slightly different too. Not a big deal, especially since the motor comes with a new tank and line.

I opted for the 20" (really 22") shaft, not the 25"(27"). My Yamaha was 20" and never came out of the water. I see no reason to go 5" deeper, and pick up more drag, probably more crab pots, and not be able to stow it in the lazy-rat....

I did get the charging system. They charged me $145 for it. Again, had it on my last motor and it was nice to get a couple amps while motoring.

I went down to the boat today, was going to motor for a couple hours to make myself obey the break-in period (10 min at idle, 10min<1/2 throttle, 2hours <3/4 throttle, 3hours at 3/4 throttle.) Was a perfect day, with 10-12k and not too warm. Ran the motor a grand total of an hour.... Had a nice sail though.

Motor smoked a bit, guess that is to be expected while the rings seat. There was a bit more vibration then the 2stroke had, but then it also was a 2 cyl.

I had a consistent 3kt, at less then 1/2 throttle. I have no doubt that it will push the boat to hull speed as others have reported.

I did just order the 'High Thrust' prop, it is a 5.9999" pitch, but it has the wide blades like the Yamaha 4 strokes do. I would have had the motor delivered with this prop, but no one offered swap outs. This is not the same prop as the 6" pitch prop, but a different animal all together (bet that .0001" pitch makes all the difference.

OBTW Tony, I found the reommendation Mike made on the 'outboard' thread;

Mercury ,Nissan & Tohatsu ( same motor, all made by Tohatsu ) recommend a 8x7 prop on the 6 ,5 & 4hp for displacement hulls ( the 4 comes with it ) the 6 & 5 come with a 'square prop' 8x8 ( actually 7.9x7.9 ).
My mechanic , from his experience , say to skip the 7 and drop to a 6 or 6.5 pitch . He's a licensed Nissan service center and seems to know what's up .
I'm going to buy a 8x7 try it and log with the GPS what it does then have it re-pitched to 8x6 and see what that does .
The following is over-simplified and not scientific;
at 4000 rpm the 8x8 prop is trying to go somewhere between 20 and 30 knots . Not going to happen on an Ariel .
At 4000 rpm the 8x6 prop is trying to go somewhere between 12 and 20 knots .
now you have slip and losses that can be 50% which brings you down to 6knots which is close to hull speed .
All that wasted revolutions on the 8x8 is like spinning the tires on a car , not getting you anywhere fast , the 8x6 is like switching to a fatter tire with more tread ,or a lower gear, that delivers all the bite to the road and propels you forward & stops you when you engage reverse.
The only drawback about downpitching ;
If you use the same motor on a dink or skiff that planes , it wont go as fast because you have shifted to a lower gear .
It only takes 5 minutes to switch props so buy a spare and have it pitched lower .

I also ordered a few spare zink's and a waterpump rebuild kit. I looked at the 'vertical pull' option, but at $129 I think I am fine just pulling at a bit of an angle. It is funny, I recall reading someone here say that the nissan vertical pull option routed the pull cord out the top of the cowl, the one offered now does not do that... it is just an elbow that screws to the recoil starter and comes out the front and turns up... seems like it would add a bunch of friction and chafe to me.. maybe they have some special stuff in there. For the price, maybe so.

Overall happy so far, will report the performance of the new prop when it arrives.

[c_amos]

The new Tohatsu is sitting out in my shop right now, the oil is still draining from the first oil change. It has taken me almost 2 months to get the 10 hours on the motor, since I usually only motor a few minutes at a time to get in and out of the slip.

I had some oil burning in the first couple hours, mostly noticed it on start up. I think it was just the rings seating. I did notice that it was worse for the first couple minutes after starting, which normally would indicate leaky valve stem seals... but I think it had more to do with the fact that the motor was stowed on it's side in the lazy rat. (yes I did only stow it on the side with the tiller handle as per the manual.)

The motor starts on the second pull every time, and has a short warm up time. I like the angle of pull through the original cut out in the cockpit and am no longer interested in the 'vertical pull' option. I think it would be awkward for me, and looking at the $100 + kit I notice that it does not have a pulley to change the direction of pull, but just a curved tube. I wonder what the friction would be like... but don't think the option is something I want anyway.

I opted for the 20" shaft (really more like 23"). My Yamaha had a 22" shaft, and did not cavitate even in much chop so I saw no reason to go longer. It is a close fit in the lazy-rat hatch anyway, so I would not want the 25" shaft for fear it would not fit (or at least be tougher to put in).


I do notice a bit more vibration then I did with my old motor (2 cyl, 2 stroke Yamaha 6). Not so much that it is distracting. A 1 cyl inboard vibrates much more then this outboard.

I do like that I can close the lazy-rat hatch and not have the motor choke out on it's exhaust like the 2 stroke did. I have not tried to do this for prolonged running so I don't know that it can't happen, just that it does not happen as quickly.

I did get the optional charging system. I have seen 2.5a on my Link battery monitor, but suspect that the charge rate would be higher if my solar panel were not keeping the battery nearly full all the time.

The zink has only spent about 3 weeks in the water total. I pull the motor and lay it in the lazy-rat when I am sailing every day or nearly so. I was disappointed to see that the zink was nearly 2/3 gone after a total of 3 weeks. I used to get 6 - 9 months on the Yamaha zink but it was at least 4x as large. I also don't know how hot this marina is, so that might have something to do with it.

I Did buy the 'high thrust' prop (5.999 x 8). I changed it out pretty early in the break in period so I have to re-mount the stock (7.8 x 8) prop to do a real comparison. I bought the prop as much for it's big flat blades as anything, as the one I had on my Yamaha seemed to back better. I did notice some difference in the backing, but will do more testing later.

Let me see if I can post some pictures.