yamaha 75 running problem

[jason_rst]

i have 1985 yamaha 75hp 2 stroke,
the problem is when i put the throttle down its not picking up as it should, it seems to sort of miss fire but not all the time. if i full throttle it wont pick up no where near like it should but sometimes it will but then dies off without me touching anything!!! ive changed the plugs, could it be the mix? im running 50:1 but some people are telling me yamahas run 100:1
can anyone help please!!!!!!!

 

[jason_rst]

Re: yamaha 75 running problem

^^^^^^^

 

[rodbolt]

Re: yamaha 75 running problem

check compression, test spark fix the fuel system.
the carbs on that motor are fairly simple and easy. use the service manual and its no worries.
post the full model number of the tag on the port bracket.
keep the 50/1 mix

 

[jason_rst]

Re: yamaha 75 running problem

will do thanks rodbolt, ill post up the model number when i get down to my boat later tonight, thanks for your help