Yamaha Help Needed 50 HP Jet

[retired navy]

Running out of ideas for 50 Hp Jet drive 1990<br />model. Engine idles/starts fine. To date we've done the following.<br />New Plugs/Fuel<br />Replaced Head Gasket<br />New Coils/Spark verified<br />Rebuilt Carbs<br />Good Compression 110 all 3 cyls.<br /><br />Under high loads/power setting engine has sounds of missing and poor performance. Audible missing and loss of power.<br /><br />Any ideas where to run to now?????<br />RMR sends.

 

[12Footer]

Re: Yamaha Help Needed 50 HP Jet

Try running some 2cycle decarb cleaner through it. It might be reed related.<br />Does the engine get wet while operating? <br />If so, waterproof the HV electrics.<br />It might be a leak in the water jacket somewhere too,but the plugs would be a dead giveaway.<br />Kill the engine at wide open, and pull the plugs. That would at least give you an idea of which cylinder is floppin, and a better idea of whether it's fuel or fire problm.<br /><br /><br /><br />------------------<br />Water,water everwhere...And all I can catch is CATFISH!!!

 

[Riverjet]

Re: Yamaha Help Needed 50 HP Jet

Pull the carbs and check the reed valves. Probally one broke or bent or sticking<br /><br />------------------<br />Heaven is a shallow river and a jet

 

[retired navy]

Re: Yamaha Help Needed 50 HP Jet

Thanks,<br /> We're still leaning towards timing and potential sensor coils. Found timing off quite a bit and read coils out accordingly. High speedcoil: 97.7 (red/white lead)<br />Low speed coil: 9.94 (green/white lead)<br />Ignition coil: 9.92 (black/white lead)<br />Charge coil: 307.5 ()brown lead/blue lead)<br /><br />Cleaned apparrent cylinder again with de-card fluid. After test tomorrow will re-consider reed problem. Thanks much<br /><br />model 50 ESDJD Yamaha<br />6H5S 081755 Ser #

 

[retired navy]

Re: Yamaha Help Needed 50 HP Jet

Thanks 12 footer, see reply to river jet for update. Appreciate the help. Retired navy