YAMAHA 6/8 Outboard, slow running problem

[galion22]

My Yamaha model 6/8 (6C), 6HP two stroke twin outboard starts OK in the start position but needs momentary choke assistance even once warm. Momentary means that I have to get the choke back in quickly before it stops. Now it will rev up but will not run slowly i.e. tick over or idle. If I close the throttle below the start position she just dies. I can't use it like it is. The motor is 6 years old but has been little used and looks like new. Any ideas please?

 

[Talbot]

Have you changed the spark plug and changed and re-set the points?

 

[Blueboatman]

Blocked slow running jet? After checking and gapping the spark plugs ,a very common slow running fault is because ..... Old fuel in the carb goes gummy,we always used to run the thing out of fuel if it was not to be used for a while . Firstly try running the engine hard and simultaneously shutting off the fuel,it may clear itself as it runs dry . Secondly ,You may get lucky with a can of fuel varnish remover,from the garage/Halfords ,or thirdly ,probably as quick and cheaper to dismantle the carb and clean the jets using neat petrol,just make sure you have really good fitting screwdrivers to unscrew the jets,as they are made of brass .
And finally (!), consider buying an extra inline fuel filter for a couple of quid,they are made of clear plastic and act as the first line of defence against grotty fuel getting to the carb.

 

[graham]

Re: Agree with blue boatman.

my 5 hp 2stroke Yamaha suffered the same symptoms and was cured by taking the carburettor to bits and cleaning.

I bought a spray tin of carb cleaner in a motor parts shop.

I am not a skilled mechanic but found it easy enough to get the carb off remove the plastic air box first then its just 2 nuts and the throttle/choke linkage.

Despite usually running the motor until the carb was empty it had still gummed up . AS a pessemist with things mechanical I was pleasantly surprised when it ran perfectly after.

 

[chippie]

I had the same problem on my 8hp yamaha. Same solution as the others, a good strip and clean of the carb.