2013 Yamaha Vx Cruiser Horsepower
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Discussion Starter · #1 ·
Hi Guys, I have a new to me 2013 VX 1100 4 stroke. It will only do 44 mph at 7000 rpm. I believe that it should do 52 mph at 8000 rpm. I have changed the plugs and made sure the oil level is correct. This ski only has 26 hrs on it and will only do 44 mph. Any ideas out there?
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Next step would be to check the compression. It should be close to 200 psi per cylinder. If the compression is good, I's suspect a clogged fuel injector.
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Discussion Starter · #3 ·
Ok. I will check the compression first. How would I check the injectors?
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On late model Yamaha 4 strokes a common mistake is over filling the oil, because people do not know the correct oil check procedure. The correct way is to start a cold engine with the boat sitting level, let it run for 30 seconds, shut it off, then check the stick. The Yamaha engine moves the oil around to the correct locations when you do this. What a lot of people do is check the oil after it has been pulled on a trailer, up a hill or a ramp or after the front of the trailer has been propped up to drain out the bilge. Even though you return the boat to a level position, the oil is pooled in the wrong places so the dip stick reads low. Thinking the oil is low they put more oil in and overfill. The excess oil slows down the crankshaft as it paddles through the excess oil in the pan and the oil gets into the tops of cylinders. There are a variety of other things that an overfill of oil will do but one thing it will surely do is limit the engine's ability to spin.
You are right to say that 44 Mph is a bit slow for that model. Most VXs I have driven will get 50~52 unless you weigh 300+ lbs. or the bilge is full of water. Also, be sure your speedo pickup is not clogged.
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Discussion Starter · #5 ·
I removed some of the oil the other day on the water, because it was over filled. I sucked about a liter out. There was no oil in the air breather, So I must have caught it in time. I'm only 200 lbs, so weight should not be an issue. What compression should I be getting? Cold or hot?
Is it ok to rev these up with no load on the motor?
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Discussion Starter · #6 ·
We checked the compression with 2 different gauges. Engine was warm and injector connectors were unplugged, throttle trigger was held wide open. 145-150 psi on all cylinders... All I can think of is that the PO didn't brake it in properly?
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Do the oil check procedure again that I described earlier. Does that have a screw in dip stick or a just a straight push in? If you have the screw in type, read the manual to see if you screw in the dip stick to check it or just dip it without screwing it in. The oil level should be between the top and bottom marks (not all the way to the top). If you had too much oil, you could have fouled plugs too.
Do you know if the previous owner ran 10% ethanol gas in it? Find some non-ethanol gas. It is usually sold near lakes and at marinas. Ethanol can gum up injectors if allowed to sit for a month or 2
I don't know the compression spec on that model.
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Discussion Starter · #8 ·
I have been checking the oil correctly. On this model you have to screw in the dip stick all the way in order to get a correct reading. We are good on the the oil. I'm not sure what gas the previous owner used. How can I tell if the injectors are plugged? Can I just run the ski and pull an injector out to check the spray?
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Compression check:
1. Warm the engine, and be sure the battery is fully charged
2. Remove all plugs
3. Attach compression gauge to one cylinder
4. Hold the throttle wide open
5. Hold the stop button then push the start button to turn the engine over. This will retard the spark, and protect the ignition system from damage
6. Repeat for all cylinders
Good numbers on a VX will be close to 200 psi per cylinder with no more than 14 psi variation between cylinders. 164 psi is considered the minimum number for the engine to still be able to operate properly.
I'd check the numbers again. If you are truly only getting 145-150 psi, you either have a valve or piston ring problem. Put a few drops of oil in the cylinders and check again. If the numbers go up, then you have a piston ring problem. I'd try adding some Yamaha Ring Free Plus to the fuel (2 oz./10 gallons) and run a couple of tanks through to see if this will improve the compression.
If the numbers stay the same after you add the oil to the cylinders, you have a valve problem, and unfortunately there is no easy fix. You are looking at a top end rebuild.
Only check the oil level with the engine hot. You need to run it on the hose at least 10 minutes to get anywhere near an accurate reading. Best time to check is on the water after you have ridden for at least 20 minutes. Screw the oil cap all the way down to do the check. Proper level should be 1/2 way between the marks on the stick.
You have to remove the injectors from the fuel rail to check them. There is probably a local shop in your area that will check and clean them for you. Typically runs about $20 per injector. You can check them yourself, but it is a little dangerous to rig them up and run fuel through them if you don't have the proper equipment, so I don't recommend it.
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Discussion Starter · #10 ·
Thanks for all your help guys. I will keep you in formed.
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Discussion Starter · #11 ·
Did the compression twice with oil in the cylinders (maybe a bit more then 2 drops). First time testing numbers got to 180-200 on 2 cylinders while others were a bit lower, I suspect we had an inconsistent amount of oil in cylinders. The second time testing all cylinders were ~160-170 psi.
We are going to give Ring Free Plus a shot. Although, I cant imagine with only 26 hrs on the machine that it could have even burned enough fuel to build up enough carbon deposits to cause such low compression numbers.
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Did you check the water separator? It is a little plastic cylinder that is likely attached to the inside ceiling of engine compartment. It removes water from fuel. You have to open the valve on the separator to dump the water out of it. Also, change out the fuel filter, it could be gummed up and restricting fuel flow.
Also, does the motor idle smoothly? If you have a no wake feature, does it run smoothly? If you have an injector that is clogged, it may idle rough. I think Yamaha markets a gas treatment (has detergent in it) that should neutralize gum. If your compression is good, then rings and valves should be OK and it probably is an injector or spark issue on one of the cylinders. I would say you are stuck in low RPM mode but 7,500 RPMs is way too much for low RPM mode. The max RPM spec on that model is 8,000. On the 1.8 liter motor in the FX HO series, the max RPM spec 7,400.
I guess there is some potential that it wasn't winterized and there is a crack in one of the cylinder heads that doesn't leak water into the oil. If you had a blown head gasket it would likely be blowing between 2 cylinders but the compression check doesn't support that idea.
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We are going to give Ring Free Plus a shot. Although, I cant imagine with only 26 hrs on the machine that it could have even burned enough fuel to build up enough carbon deposits to cause such low compression numbers.
If the engine was not winterized correctly the rings corrode in the pistons, and don't expand correctly, so the problem may not be carbon, but rust.
Therefore, I don't know if the Ring Free will help or not, but I have seen it work miracles.
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Discussion Starter · #14 ·
It does idle a little rough. I'm going to try the Ring Free and see how that works before I pull it apart. Maybe some gas treatment as well. I do suspect that it was not winterized properly as well. Thanks again guys!
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This is a vexing problem for a ski with only 26 hours. Here are few more thoughts.
If you had rusted piston rings, would you not expect to have low compression and oil consumption? Sounds like your compression is good. I suppose you could have bad valve guide seals which could be indicated by burned oil in the exhaust (blue smoke) during initial start up and fouled plugs.
If you have 2 side by side cylinders with reduced compression, it may have a slightly blown head gasket between those 2 cylinders. It may not be blown bad enough to leak coolant into the oil or into the combustion chambers.
A worn cam shaft would reduce valve duration but good seal and allow for good compression.
If the motor top end was ever disassembled and put back together incorrectly (1 tooth off on the camshaft) it could run but would run poorly.
Does the ski have the original jet pump and/or has the pump been replaced with an incompatible pitch? A mismatched pump could make too much pressure, then the engine may not be able to wind up to 8,000 RPM. The ski would run ok for puttering around but would not accelerate as fast as other VX skis, it would loose lose top end and the motor would under rev. The pitch on the blades in the pump needs to match the power specs of the engine and the weight of the boat. If you have an aftermarket pump that was intended to go in a VX with an engine performance kit, the engine may not be able to leverage the pump. It is the same issue on a boat with an outboard motor. Too much pitch on the prop, the engine will not wind up and there is a loss of top speed.
2013 Yamaha Vx Cruiser Horsepower
Source: https://www.pwcforum.com/yamaha-jetski/41969-2013-vx-slow-top-end-speed.html
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