mecury 850 NEED HELP PL................

[kbunch101]

yes i bought a bass boat i noticed when i was wide open the rpms where at 4100. is this right that was also after i set the tilt that is the best it would do and i do whant to tank every one for the help i was a johnson boy till last year always herd mecrs wasnt any good boy did they lie lol thanks a bunch kevin the mod # is 4295689 blue band it is a 1976 mod.

 

[Chris1956]

Re: mecury 850 NEED HELP PL................

kbunch, You should be running at least 5000RPM on that motor. If the compression is good, and the motor is running on all 4 cylinders, you will need to reprop the motor with a smaller pitch prop. Every 1 inch decrease in pitch should add about 200 RPM. I would think 15-17 inch pitch would be about right for that setup. Of course that is a total guess based upon common Bass boat hull weight and type.<br /><br />Here is a thought. Check the current prop to assure it is a proper one for that motor. On these old motors, sometimes folks will install any prop just to sell 'em.

 

[NathanY]

Re: mecury 850 NEED HELP PL................

What year is this motor?<br /><br />operating ranges for 850 are as follows:<br />1973 4800-5500<br />1974 4800-5500<br />1975 4800-5500<br />1976 4800-5500 850XS 4800-6000<br />1977 4800-5500 850XS 4800-6000<br /><br />There could be lots of reasons that you do not reach full RPM, ranging from electrical, to fuel, to being over propped. We are going to need more info in order to help you.