thoughts on idle vs gear,mercury 850

[kazek]

1975, 850 mercury motor is on 17 ft fiberglass Humber boat from 1970's. I can't get merc to go into gear without dying form 800 rpms in neutral. Have to have at least 1500 rpms to shift into gear. When I get it going, the tach shows 3500 rpms at WOT. Carbs were done, same as sync and link. I found forums here unbeatable for help,and for that i thank you all for your input here.my question now is. Would a 21pitch propeller cause this motor to act up? should i go with a lower pich like a 17p?

Is a 21 prop creating too much load on the engine to die in gear?

 

[eroth111]

Re: thoughts on idle vs gear,mercury 850

1975, 850 mercury motor is on 17 ft fiberglass Humber boat from 1970's. I can't get merc to go into gear without dying form 800 rpms in neutral. Have to have at least 1500 rpms to shift into gear. When I get it going, the tach shows 3500 rpms at WOT. Carbs were done, same as sync and link. I found forums here unbeatable for help,and for that i thank you all for your input here.my question now is. Would a 21pitch propeller cause this motor to act up? should i go with a lower pich like a 17p?

Is a 21 prop creating too much load on the engine to die in gear?

I had the same motor with the same problem. When you pump your fuel bulb does the bulb stay stiff or never get hard?

 

[Chris1956]

Re: thoughts on idle vs gear,mercury 850

The 21P prop will not cause the motor to die in gear. It will limit the RPMs at full throttle, however. In my experience, unless that boat is real light, you probably have too much pitch. I ran an 850 on a 16 foot winner which was maybe 400#. We ran a 19" pitch prop.

Dropping it into gear at 1500 RPM will destroy the gears. It is likely your carbs are dirty which is why it stalls.

 

[kazek]

Re: thoughts on idle vs gear,mercury 850

got the boat on the water again last nite.worked bit better when wormed up for about 20 min.was able to drop motor to 1000 and shift the gear occasionally without engine dying.seems that it works better with carb idle screws out about 2.5 times.is it correct setting?the bulb was hard till i over did it pressing it too hard i guess.had one short squirt of gas from top carb and bottom carb squirting now.i will have to work on carbs again.
found one more strange thing.my multimeter starts doing "funky"numbers (quickly changing and unreadable)not even touching the motor.cant take any mesurments when engine is running.could this would be caused by poor spark plug wires arking?

 

[Chris1956]

Re: thoughts on idle vs gear,mercury 850

2.5 turns on the idle screws could be right. It is a bit more that they usually need, but not much more. You should hear or see the spark plug wires arc, if they are doing it.

 

[kazek]

Re: thoughts on idle vs gear,mercury 850

I will try fire her at night and check spark wires.hope neighbor likes sound of beast running at night .thanks for replies