A little help with motor boat motor yamaha 85hp 2 stroke

Hi under load its not got much go it sounds like it want to go kind like bogging down

what im wondering is what can ii look at do to  try to fix it myself without  taking it to a mechanic yet

it was runngn fiine but has sat for awhile im thinking of running it out of fuel and putting all new fuel in it im not sure if any water in tank or not ..

Faulkner Family's picture

Posts: 14894

Date Joined: 11/03/08

 two things to look at first.

Sat, 2018-09-29 16:38

 two things to look at first. 1 is fuel like you said  the other is check your if its been sitting for a while check there is no blockage allowing air into the tank , no air flow will result in the motor starve for fuel


RUSS and SANDY. A family that fishes together stays together

Posts: 101

Date Joined: 17/08/14

 As above but also poss stuck

Sat, 2018-09-29 17:11

 As above but also poss stuck closed thermostat. Some two strokes have a temp safety so will only rev to about 2000 if it gets hot to avoid cooking engine. 

NORUN NOFUN's picture

Posts: 505

Date Joined: 15/08/11

I have seen fuel that has

Tue, 2018-10-02 12:13

I have seen fuel that has turned to jelly in the carbie bowls, this particular motor ran fine at idle then ran like shit under load due to the increased angle of boat shutting down the float prematurely and closing off the needle valve.
The worst part was that it was the last thing we checked - live and learn.

Posts: 636

Date Joined: 11/06/10

i think i have sorted the

Tue, 2018-10-02 18:45

i think i have sorted the fuel issue now will find out next time i take it out then i shall be going ocean and get some squid and fish