can't get right idle setting

camawelander

Seaman Apprentice
Joined
Jun 4, 2008
Messages
34
i have an 89 force 35 that i am trying to tune.

the book says idle should be at 600-750
when i set the idle this low the motor really wants to choke and sputter, and 1/2 the time will stall when put into gear (the shifting is super smooth at this rpm, no clunk at all) - at this rpm the motor doesn't always want to restart and will take 3 or 4 key turns.

when the idle is set at around 900-1000rpm - it starts and restarts on the first key turn and runs great, but when put into gear there is a slight to moderate clunk when engaging (should there be any clunk when shifting?)

what is going on - is my motor just one that likes a higher idle setting?
could my books #'s be incorrect?
is there another carb adjustment to make?


Other than the idle issue the motor runs perfect at any throttle input

i recently installed a tiny tach and i seem to be getting consistent readings- the tach will bounce up or down 10 to 20 rpm every few seconds but for the most part it seems to be hooked up properly (red wire wrapped around the spark plug wire 5 times)

I have just done a 3 part seafoam de-carb and have new plugs installed
thanks for the help
 

maxum247

Lieutenant
Joined
Sep 18, 2007
Messages
1,363
Re: can't get right idle setting

There's the idle mixture screw on the carburetor and the idle speed adjustment screw on the tower shaft down under the shift cables if your 35 is anything like my 125.
Good Luck!
 

eurolarva

Rear Admiral
Joined
Jun 24, 2003
Messages
4,182
Re: can't get right idle setting

The idle circuits in the carburetor are always the first to gum up. If you can not get the carb adjusted by the manual procedure, take the idle mixture screw on the carb off and spray some cleaner in hole it came out of with the spray straw. Wait ten minutes and spray again. Then reinstall the mixture screw and spring. While you have that screw out look at the tip and make sure it is nice and round and not bent. If it is deformed you can try and touch it up with sand paper or buy a new one.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: can't get right idle setting

The higher idle speed is an old trick, the raise air velocity makes for better fuel atomization, and a smoother, more complete combustion/more power.

The drawback from a higher idle speed is the beating one the engagement dogs of the gear set.

As the previous poster noted, the 'correct' fix is better fuel control with a new idle mixture needle and maintain the stock prescribed idle speed.
 

john from md

Commander
Joined
Apr 13, 2008
Messages
2,184
Re: can't get right idle setting

Make sure you are adjusting the idle in the water and not on the muffs. You will not get it to run right if you adjust it on the muffs.

The clunk is normal due to the design of the way the gears are meshed. You want the engine to clunk, you do not want a smooth shift as it will cause more wear on the lower end.

Don't worry about the tac bounce. It is working off of raw stator voltage on a two stroke engine. Every cough from the engine shows up on the tach.

Hope this helps,

Regards,

John
 
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