2001 Seadoo Sportster LE. Just got it!

[Bonmotwang]

oil consumption calculated by the manual

According to the manual the oil consumption is about 1ml/min @3000RPM.
@5000RPM it will be 1.7ml/min

So if running @5000RPM for 1 hour, the oil consumption is about 0.1 quarts (102ml).

 

[Sportster-2001-951C-Stock]

I suppose from this chart, a jet ski/boat must always run WOT. Well, at least we have maximum fuel consumption info so we can plan for the worst case. If they really run this way, and I think some actually do (max or min throttle, nothing between), I can understand why some people claim the 951 cannot go past 250 hours running.

http://www.seadoosource.com/fueleconomy.html

BTW, once I swapped a carb between a boat and a car, they had the same carb. The reason was b/c I wanted to find the reason why the car was getting poor fuel mileage, and I suspected the trouble was was the carb.

I was right, the fuel consumption of the car improved considerably. But, the fuel consumption of the boat didn't suffer. This is b/c the boat doesn't run at the idle and low speed fuel circuit crossover as much.

 

[IDoSeaDoo]

I test fuel consumption by traveling in a straight line and maintaining the same RPM from one point to another point and directly back along the same path. I do this either to a certain point, or for a certain time (or both). I start with a full tank, then when I'm done, I fill it back up and see how much fuel it took for me to cover that distance. Then I use either google earth or a GPS unit (that I had on while making my test-run) to see how far I got. Divide miles by the number of gallons you put back in and there's your mpg. Or you can take the gallons and divide by time to get a gph consumption rate. I love seeing what other people get too and comparing it to my numbers. it's very good to know if you're trying to plan out a long trip.

 

[Bonmotwang]

2001 seadoo sportster WOT data: Fuel tank last 1 h 15 min, Oil tank last 13 h

I found this from the shop manual:

Maximum fuel consumption at wide open throttle: 14.5 Gallon/hour (55 L/hour)
Cruising time at full throttle: Full tank without reserve 1 h 15 min, Fuel tank reserve 17 min. (this is strictly calculated from the tank size and reserve percentage)

I made a mistake on calculating the oil consumption. The 1mL is for each port.

The shop manual says: 947 engine run at 3000 RPM, 0.83-1.01 mL / 30 seconds each port.

So at 6500RPM cruising speed, it consumes oil at 3.6 mL - 4.38 mL / 30 seconds total.
In 1 h 15 min, it consumes oil 540 ml - 657 ml (0.14 - 0.17 Gallon)
So a tank of oil can last 13 to 16 hours.

Is this close to the reality?

 

[Sportster-2001-951C-Stock]

So in this case how many gallons (or liters) of fuel are burned per gallon (or liter) of oil at operating speed?

Working towards a ratio of fuel/oil, I'm figure by my memory about 80:1 based on eyeball metrics, consuming ~40gal of fuel and ~1/2gal of oil.

if 13 tanks of fuel at 20gal is 260gal total, then assuming the oil tank capacity is 3.5gal, this seems to suggest a consumption ratio of 75:1, or about the 80:1 I experienced. This seems greater than I would think but the numbers seem to confirm this ratio.

17 minutes fuel reserve time seems generous. I don't think my test result was quite that, maybe 10 minutes, because I wasn't that far away and ran out of fuel pulling up to dock.

I estimate the cost of oil consumed by this boat last season was about $22, nearly the same as the cost of a 4-stroke stern drive oil change. I'm certain the total amount of fuel consumed vs operating hours was considerably more than would have been consumed by a stern drive.

 

[Bonmotwang]

So in this case how many gallons (or liters) of fuel are burned per gallon (or liter) of oil at operating speed?

Working towards a ratio of fuel/oil, I'm figure by my memory about 80:1 based on eyeball metrics, consuming ~40gal of fuel and ~1/2gal of oil.

if 13 tanks of fuel at 20gal is 260gal total, then assuming the oil tank capacity is 3.5gal, this seems to suggest a consumption ratio of 75:1, or about the 80:1 I experienced. This seems greater than I would think but the numbers seem to confirm this ratio.

17 minutes fuel reserve time seems generous. I don't think my test result was quite that, maybe 10 minutes, because I wasn't that far away and ran out of fuel pulling up to dock.

I estimate the cost of oil consumed by this boat last season was about $22, nearly the same as the cost of a 4-stroke stern drive oil change. I'm certain the total amount of fuel consumed vs operating hours was considerably more than would have been consumed by a stern drive.

The 2001 Sportster LE has a 2.3 Gallon oil tank. So the ratio is about 117:1.

 

[Sportster-2001-951C-Stock]

The 2001 Sportster LE has a 2.3 Gallon oil tank. So the ratio is about 117:1.

This size tank makes more sense, it looks like about 2gal or slightly more. But I don't agree with 117:1, my rough calcs are more like 80:1 and even that seems skewed higher than I'd expect.

So if my estimates are correct then one tank of oil should last about 9 tanks of fuel at an average 5200 RPM operating speed.

 

[Sportster-2001-951C-Stock]

We used to run 16:1 on the old motors that used babit type before roller bearings appeared, and for these I still do, despite today's oils are exceptionally better.

80:1 is way up there, and makes me nervous.

"If you are running premix only on one of our engines we recommend 32:1 fuel oil ratio for break in and 40:1 after the initial engine break in. "

http://www.fullboreonline.com/tech_tips.htm

 

[Bonmotwang]

Maybe the oil flow rate in the oil pump is not linear when the RPM is greater than 3000RPM, which will explain the difference between my calculation and the realities.


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[Sportster-2001-951C-Stock]

I wouldn't expect oil consumption would be linear with RPM but maybe it's more correlated with quantity of power generated. Might be a reasonable approximation to assume a 40:1 ratio at WOT and make a linear graph to the ratio you calculated at 3000RPM to approximate the effective cruise ratio at 5200RPM, I cannot accept a 117:1 ratio.

Think of it this way, a lot of money was lost by OMC in their early attempts to run 100:1 in their outboards, most of them quickly failed out in the field. OMC no longer makes the Johnson/Evinrude outboards for this reason and also the FICT direct injection failure incident.

You should read Gordon's ratio testing article, there are many other laboratory ratio testing articles out there beside field testing which confirm Gordon's results (less is not more).

Edit: And Gordon was a motorcycle guy, granted motorcycle engines are only air cooled but mostly his 2-stroke articles were about engines oscillating between a coasting cycle and power cycle. This isn't quite the same thing as marine engines which don't benefit from a coasting cycle, more like a continuous roasting cycle. I'm sure the water cooling goes a long way in compensating for the quantity of heat generated.

Piston/cylinder clearance tolerances are important, the CNC machining and use of aluminum alloys which have predictable expansion rates allows for closer tolerances and this is why we cannot allow our rings and lands to be coked with cheap oils that burn at low temperatures, Seadoo learned this lesson right away when they tried to use TCW oil in the Rotax, field failure rates went up and they immediately changed the spec to API-TC to address the problem of oil film failure.

The 951 has the highest ring speed of all the Rotax 2-strokes, the ring speed of this motor running 7200RPM is at the theoretical limit.

 

[Sportster-2001-951C-Stock]

The reason I refer to ring speed as opposed to piston speed (this is the same speed, right?) is b/c from my experience it's always been the rings overheating first as they cannot transfer heat through the oil into the cylinder sleeve, burning the oil film and sticking to the cylinder walls at the end of travel location, a sort of like spot welding in place mostly occurs at the top of the cylinder where the piston reaches top dead center.

I've taken apart several engines that were habitually run at high speeds and noticed there was cylinder wall pitting around the top of the cylinder sleeve where the top ring normally reverses travel.

 

[Bonmotwang]

But the residue stayed in the cylinder wall shouldn't affect the performances too much. I thought it only makes the displacement a little smaller :-D


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[Sportster-2001-951C-Stock]

But the residue stayed in the cylinder wall shouldn't affect the performances too much. I thought it only makes the displacement a little smaller :-D


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What about the precision clearance between the cylinder and piston at operating temperature, what happens when this clearance becomes zero? :O

Edit: Actually, the cylinder walls are considerably cooler in comparison with the piston itself, which will be hotter depending on the quantity of heat being absorbed into the piston crown. The oil film separates the piston and cylinder sleeve but also serves the purpose of transferring heat out of the piston and into the cylinder sleeve. In fact, one way to know if your engine has been running too hot, is by inspection the underside of the piston crown for carbon deposits. Ideally there should be no carbon deposited on the underside of the piston crown.

If the operating temperature is high enough to decompose the lubricating oil, oil varnish deposits will begin to grow on the piston skirt and in the ring lands first, not on the cylinder walls. The cylinder walls will soon be covered with aluminum from the piston if the oil film fails to keep the piston mechanically isolated from the cylinder walls.

But you're welcome to disable your oil injection pump and mix your fuel 117:1, I'd be all ears interested in hearing about the results.

 

[fredm21]

What about the precision clearance between the cylinder and piston at operating temperature, what happens when this clearance becomes zero? :O

Edit: Actually, the cylinder walls are considerably cooler in comparison with the piston itself, which will be hotter depending on the quantity of heat being absorbed into the piston crown. The oil film separates the piston and cylinder sleeve but also serves the purpose of transferring heat out of the piston and into the cylinder sleeve. In fact, one way to know if your engine has been running too hot, is by inspection the underside of the piston crown for carbon deposits. Ideally there should be no carbon deposited on the underside of the piston crown.

If the operating temperature is high enough to decompose the lubricating oil, oil varnish deposits will begin to grow on the piston skirt and in the ring lands first, not on the cylinder walls. The cylinder walls will soon be covered with aluminum from the piston if the oil film fails to keep the piston mechanically isolated from the cylinder walls.

But you're welcome to disable your oil injection pump and mix your fuel 117:1, I'd be all ears interested in hearing about the results.

What a great answer!!! Thimbs up

 

[Bonmotwang]

Nice day today. Trip was great! A lot of sale boats in the lake. Started at the dock, wife was asking how come you got so much smoke :-D
Yeah, it was from the 20mL oil

Start:
Started right away. idling at 1400RPM stable. (I did start the engine on the trailer before we left to minimize the surprises at the ramp)

Speed:
Most of time at 5500RPM, speed from 25 to 30MPH depends on the wave condition and wind direction. 5000RPM is kind of low today, maybe I just used to "fast" :-D
It was jumping on the 1 to 1.5 feet of wave. Pretty bumpy.
Engine sounded all normal, similar to the last time.

Oil:
I marked the oil tank before the trip, it did go down about 3/16".
I adjusted the oil alignment about 1/32" over the center line. Not sure if it is a smart move. The idea was to give a little bit more oil because of the low engine compression.
Just did 15ml per cylinder. I am loving the white smoke now :-D

Concerns:
One thing I noticed is the boat tends to go right, I had to hold it left to go straight. Not sure it was because of the wind. But I do need to check the steering system, because when I tested it on the trailer, turning to right was free, turning to left had some resistance or binding.

Exhaust blow out:
I did the blow out start in the drive way after driving it back home (25 minutes of driving), it started at 1500RPM for a few seconds, and then moved to 3000RPM. I have never seen this before.

Water in the bilge:
There is low level of water inside the bilge. It is too low for the bilge pump to pump it out. The bilge was dry. after the first trip, water got in there some how. and after today's trip water still there, level didn't change. Picture attached

 

[Bonmotwang]

But you're welcome to disable your oil injection pump and mix your fuel 117:1, I'd be all ears interested in hearing about the results.

Somebody told me today to do both. Use both oil injection and premix 100:1.


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[USAF_Pride]

Water is probably getting by your carbon ring. Not abnormal.

 

[Bonmotwang]

Water is probably getting by your carbon ring. Not abnormal.

Is this the carbon ring?

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[USAF_Pride]

Yes it is.

 

[Coastiejoe]

It is suppose to leak by design. The leak is what cools the Carbon Seal (CB). But the leak should be drips, not a stream. There is an update "C-clip" retainer that replaces the OEM O-ring style retainer. The O-ring fails and let's the collar move a bit and creat a small leak. If it fails entirely, the collars moves a lot and the ski can sink.


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[Bonmotwang]

It is suppose to leak by design. The leak is what cools the Carbon Seal (CB). But the leak should be drips, not a stream. There is an update "C-clip" retainer that replaces the OEM O-ring style retainer. The O-ring fails and let's the collar move a bit and creat a small leak. If it fails entirely, the collars moves a lot and the ski can sink.


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Thanks. I will keep an eye on it and monitor the water level after every trip.
And now I totally understand why Carbon ring could fail when running the engine on the trailer.


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[Bonmotwang]

Ok. Here comes the silly one. lol

Is this small leak going to sink the boat if I keep it in the water for a week?


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[USAF_Pride]

Ok. Here comes the silly one. lol

Is this small leak going to sink the boat if I keep it in the water for a week?

That is why you have a bilge pump. The pump should run automatically when water reaches a certain level. You need to test the switch (typically by filling the bilge) and see if it empties out. As long as the bilge pump runs and your battery doesn't go dead, it won't sink.

That being said, I don't think it is recommended by too many people to leave your boat/PWC in the water over extended periods.

 

[Bonmotwang]

That is why you have a bilge pump. The pump should run automatically when water reaches a certain level. You need to test the switch (typically by filling the bilge) and see if it empties out. As long as the bilge pump runs and your battery doesn't go dead, it won't sink.

That being said, I don't think it is recommended by too many people to leave your boat/PWC in the water over extended periods.

Ah ha, so I just need to leave the battery switch at "ON" position.
(I turn it off after every trip now)


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[fredm21]

Does every bildge pump start by itself when the water is too high? Same as a sump pump?