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Yamaha f50 62y 4 stroke 2003 carb model

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robanfield

New member
Hi to all,
The above engine was not running correctly so I stripped the carbs out and found that when I had previously serviced the engine one of the 0 rings had slipped out of position. (MY FAULT)
I renewed 0 rings and refitted carbs and started engine. It was 100% better to start and then it started to run as if it was on choke and at 1500 revs but running "lumpy" not smooth.
I could not slow down idle speed.
I have fitted new plugs.
I am now going to change bulb and fuel line to engine.
I am going to get carbs ultrasonically cleaned but if anybody could point me in the right direction as to engine running as if on choke it would be a great help.

Thanks to all who have the time to offer help

Cheers, Rob
 
If the prime start devices are not working (or electrically connected) then they will provide too much fuel when the motor is warmed up causing it to run rich.

If the carburetors are not synchronized it can make all the difference in the world in idle and run quality.
 
Thanks boscoe, I am in the process of refitting the carbs after ultrasonic cleaning and soaking and am hoping to get help with balancing.
I do not know about prime start electrics I have a manual prime start lever next to accelerator.
Thanks again for your time.
 
These are the gizmo's I am talking about.

What is this lever that you are talking about? Is it part of a side mount control box? If so, that has nothing to do with starting the motor.

 
Hi, I have 4 carbs there is a solenoid and a black round thing with 2 wires coming out of it. The lever is on side of control box.
I will try and put a picture on.
 
The lever on the side of a 703 control box is just a means to advance the throttle without putting the motor into gear. This gizmo should not be used when starting a motor. In fact, it can make the motor harder to start.
 
4 carbs no chokes - two primers, the primers are open when cold, they also are two needles that are seated in wax --
they need 12 volts to warm the wax and release the needels to lean out engine -- they should get the 12 volts when
engine is running.
 
Thanks bundee, thats something else to take a look at. When I took the carbs apart the small jet on the bottom of each carb was screwed right in, thats how they have been from new, is this correct. The engine is a bit rough when starts although when revved it clears although every time starting is a problem. I think I will blow carbs out with air and buy a Carbtune kit. Thanks a million and if you can think of anything else I would be grateful.
Cheers, Rob
 
robanfield said:
Thanks bundee, thats something else to take a look at. When I took the carbs apart the small jet on the bottom of each carb was screwed right in, thats how they have been from new, is this correct. The engine is a bit rough when starts although when revved it clears although every time starting is a problem. I think I will blow carbs out with air and buy a Carbtune kit. Thanks a million and if you can think of anything else I would be grateful.
Cheers, Rob[/QUOT
The jet that is near the bottom of the float bowl should be tight.
dose this look like your carb set -- these carbs have got be very clean
Click to expand...
 

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bundee said:
robanfield said:
Thanks bundee, thats something else to take a look at. When I took the carbs apart the small jet on the bottom of each carb was screwed right in, thats how they have been from new, is this correct. The engine is a bit rough when starts although when revved it clears although every time starting is a problem. I think I will blow carbs out with air and buy a Carbtune kit. Thanks a million and if you can think of anything else I would be grateful.
Cheers, Rob[/QUOT
The jet that is near the bottom of the float bowl should be tight.
dose this look like your carb set -- these carbs have got be very clean
Click to expand...

Yes absolutely spot on.After I removed the smaller nut/jet there is a screw underneath which was tight on all 4 carbs, is this correct? I think there must be a bit of a blockage in one of the very small holes in the carb
Click to expand...
 
The screw underneath as a smaller hole in it, got to be clean - clean. The set of carbs in my picture had these
holes pluged, not propley drained for winter - runs not bad now (95%) hope to get it a 100% adding some sea foam to the gas tank. Keep trying
 
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