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Yamaha 50 hp 2007 model

shayne

New member
"I have just brought a new 50h

"I have just brought a new 50hp yamaha motor which I put on a 4.2 meter alloy boat. boat only weighs 190 kilos and can only achieve 35 mph top speed at 5500 rpm. They clicked the rev counter wrong so when I was running it in I was doing 6000 rpm instead of 3000. I am not happy about that as the first hour of use was 500 revs more than it should when run in. The motor now has one and a half hours on it, and I took it out the other day to try the new prop and do some fishing. When I moved to another spot I started the engine and went to move off, and it would rev to about 1200 revs then stop. After 5 or 6 attempts of this it got past that rev and seemed to go ok although not great. This happened about 90% of the times when restarted. The motor would start fine and idle fine then with a little throttle, would run as rough as and when trying to increase more it would stop. any ideas??? took it back to the shop and they couldn't find anything wrong with it. Took it out yesterday and it did the same 3 times only. I am concerned about this, and the over revving from new and also the amount of fuel this motor uses. Can anyone help?"
 
sounds like u have bad gas
tr


sounds like u have bad gas
try running it off a auxiliary tank of fuel

are u running pre-mix or oil injection
 
"Hi, The gas was just brought

"Hi, The gas was just brought from gas station on the to launching, and using yamaha oil. The other day when tried again it was new gas again, and still same problem. As for the mixture, I ts running both, pre mix and oil injected as it should be for the first 10 hours of operation. I am a boat builder myself and brought this motor new from where I work. As stated above, apart from this problem with the motor, is the running in at 6000 revs instead of 3000 which I did for about one hour as they had put the switch on the back of rev counter to suit a 12 pole alternator instead of 6 pole."
 
"No, no alams, I thought of

"No, no alams, I thought of overheating or a problem with the oil injection, but none of them. Its a bit of a mystery ( Grin)"
 
"to me it sounds like a fuelin

"to me it sounds like a fueling issue, since your not in RPM reduction mode
try draining the carbs and see if anything pops out

if the primer bulb did not go flat, then we can rule out vent line and fuel pump and fuel lines"
 
"Im not to sure if it is fuel

"Im not to sure if it is fuel as all the cylinders went dead at same time. I dont know if the RPM function stops the engine dead when giving it more gas. I thought it might be electrical, like cdi ignition or auto advance, magneto etc"
 
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