Engine up to specs?

HydroCanis

This (2003 Sundeck 217) is my first boat (4 times on the lake so far), and none of the others I've driven were anything like it as far as being outboard and a similar size engine or hull. The Yamaha 150 (V6 TXRB two stroke, apparently a standard offering with the boat when it was new) was hesitating a bit here and there at first, and the previous owner said that was how it felt the first time out every year (didn't sound like he'd been putting anything special in the fuel tank over the dormant winter months). Sure enough after an hour most of that went away (and with some SeaFoam in the tank the next time out). Since he couldn't recall having changed the spark plugs, I thought a new set might be the thing to get rid of any residual hesitation. That also proved true (though none of the old plugs looked particularly bad), as it now has no intermittent hiccups that I can feel. What it does seem to have is sort of a flat spot somewhere around the upper 3000 rpm region. Throttling it up pushes right through and it feels OK after that. I haven't driven anything with carburettors in many years, so I've sort of forgotten what it was like before EFI. Perhaps it's just me. I checked several times yesterday with a GPS device and it held a maximum speed with 4 people on board and fairly smooth water of 38mph every time (I'm still learning about optimum trim, however).

So what do you think? Is that behavior just a "feature" of that engine as you throttle past some particular point? Or is there something out of whack that I need to check into? Previous owner claimed to have zipped along at 45mph or better with 2 on board, but he was going by the (not currently functioning) speedometer, which might have been optimistic. I bought a bottle of Ring Free but haven't added it yet as I've used less than 1/4 of the (64 gallon!) tank since I added the SeaFoam.

Oh yeah, one other question... seeing as how Yamalube and a few other "premium" oils cost a lot more than most other TC-W3 rated oils, how much of the difference is really helpful and how much is just hype?

Ernest_T

I've got a 4 stroke F150 on my SD 217 and my top speed with 2 people and 1/4 tank of fuel is 42 mph.  With the boat loaded with 4 people and more fuel I can't top 40 (typically 38-39 mph).  I've always heard that the top end speed between the 2 and 4 stroke 150s is nearly idential, so I'd say your outboard is running pretty good on the top end. 

I tested a SD 217 with a Yamaha 150 2 stroke, but I think that one was fuel injected.  It was pretty smooth throughout the range.  You may just need to clean the carbs. to improve the mid-range response.  If the carbs. on outboards are like any other 2 stroke, you need to clean/rebuild them every 5 years or so.  Maybe even more so with all the ethanol that is in fuel these days.

I don't think there is anything special about Yamaha's 2 stroke oil.  The only advantage that I know of is that it seems to burn cleaner than some other 2 stroke oils in their motors.  I know on the older Yamaha 2 stroke waverunners if you didn't run Yamalube the catylitic converters would foul up pretty fast with other oils. 

I can also vouch for the Yamaha Ring Free Plus additive.  It will remove carbon from valves and free up the rings.  I'd definitely try running some through.  That stuff may fix your mid-range if it is valve or ring related.  I've seen some pretty good results using that stuff.  I'd double the dose (2 oz. per 10 gal) for the first tank.  I run it 1 oz./10 gal. in my outboard and waverunner every tank.

bshippjr

While I don't have that specific engine, I have a Johnson 150 2 stroke on my 2000 SD217 which I bought used in 2006.  When purchased, the engine ran rough and hesitated.  I was going to take it to the mechanic that had worked on my previous Hurricane, but he said that before I brought it to him to shock it with Seafoam using twice the prescribed amount and run WOT for an extended period to get the mixture through the engine.  That did the trick.  So when you use more of the exiting gas, if the Ring Free does not work, you might try this.  I also use Seafoam regularly.

My speedometer does not work, but on a GPS with a couple of people, full tank of gas, and the storage compartments filled with too much stuff, I get around 36 to 38 mph at WOT, so I don't think you are out of line with your reading.  Most of the time spent cruising at 21-22 mph.

For your oil question, I use Pennzoil XLF, a synthetic blend that I buy at Academy Sports and have had no issues.

Also, unless an additional gas tank was added, the standard capacity is 52 gallons.  

HydroCanis

Thanks for all the info and advice. It does sound like I'm getting the top end I should, compared to your experiences. The only time I had the GPS on board was with a full tank of fuel, and yes, for some reason (of which I'm glad), it has a 64 gallon tank. I know because the seller and I ran out of fuel just as we reached the marina during a test run and I then filled it. Ouch. I hadn't thought about the drag from the fuel weight. I figure 64 gallons of gasoline is almost 450 lbs.

In an auto, I try to never run the tank dry as I'd rather leave crud in the tank than suck it into the engine. I assume that would apply to outboards as well? I doubt there's much water in there, though, since most all the fuel around here has 10% ethanol.

Anyhow, Ring Free going in next.

1pointofview

i bought my boat new last year and filled up the 49 gallon tank with it and 13 gallons of fresh water drove 8 hours home and could tell a big difference with all that extra weight.  I do not put more than a 1/2 tank in mine now.  That way I am always keeping pretty fresh gas in the tank and not carrying around much excess weight as I normally have 8-9 people in my boat each time we go out plus all the drinks, lunch and such we bring on.  makes it easier and more efficient on the trailer and in the water

HydroCanis

So... some Ring Free, some more running, and when it runs well, it runs well. It held at 40mph with 2 on board and about 40 gallons of fuel, and it holds at 38mph with 3 and a full tank. No hesitation or flat spots. So I'm pleased with that. But the exasperating mystery: at seemingly random times (generally not in the first few minutes of running), it bogs and won't go beyond, say, 3000 rpm. Pushing the throttle further gets nothing more, but it runs OK up to that point. After 5, 10, 15 minutes, full power reappears and it runs well again. To me, it feels like a lack of fuel flow somewhere. I don't seem to have an oil-filter-sized water/fuel separator, just a little clear plastic thing under the cowling. In and out lines are both at the top, leading me to believe water would settle there. The first time I cleaned the screen filter in it, I think it had some water in it. The second time, seemingly none, and no dirt. I think it may have never been cleaned before the first time I did it. Someone said that the priming bulb would sort of collapse if there was a restriction before it, and that doesn't happen, nor does the bulb feel too soft during problem times. There could be something clogging the carb jets, but it doesn't seem like additional stuff is going through the filter. I don't know how to tell if the jets/float bowls (?) are clear without taking the carbs apart, which I'm not prepared to do myself. I removed the cover and looked down the carb throats, and they look like new. Cleanest carbs I've ever seen. So what else could be wrong? It appears to have two fuel pumps, both of which supply all three carbs. Could one of them be flaky and working properly only some of the time? What does a typical Yamaha fuel pump failure feel like? This engine probably has less than 200 hours on it, but it's 11 years old now and AFAIK has not had servicing other than bottom-end lube changes (and me replacing the spark plugs). No alarms or warning lights, and cooling water appears to squirt out well. Any ideas?

HydroCanis

"Final" update on this... carbs did indeed have some crud in the bowls, local dealer rebuilt them (I would tackle it over the winter but not when I want to use the boat in the next couple of months because I'm slow and haven't worked on this type of carb before) at a fair but significant cost. Two of the three—the lower two—had bits and goo in them. It runs smoothly without hesitation and I'm happy. Max speed on a smooth lake: 38mph with 3 on board and a full tank, 40-41mph with 2 on board and 1/2 tank of fuel.