89 115hp yamaha v4 cough erratic idle

cookiedoh

Seaman Apprentice
Joined
May 13, 2006
Messages
36
I have a 1989 v4 115hp yamaha outboard. It was running a little rough below 2000rpm and seemed like it was smoking a bit too much. I turned the pilot screws in (leaning) adjusted the idle set screw on carbs to 800rpm (using dash guage, I know I need to get a more accurate one) timing was at about 2*ATDC, book said 4-6 so I moved it out. Ran great for on the first and second run, real smooth at all RPM. Third time out, stalls at idle, stalls at low rpm, and runs with a cough at idle. RPM's erratic at idle, runs at 900 for 3-5 seconds, coughs and drops to like 300rpm, stays down there for a little while then slowly works back up to 900. I tried putting the pilot screws back, re-checked timing, didn't seem to make any difference.

Fouled carbs, plugs, coil, compression...something I'm not thinking of? Point me in a direction? Thanks.
 

cookiedoh

Seaman Apprentice
Joined
May 13, 2006
Messages
36
Re: 89 115hp yamaha v4 cough erratic idle

Are pilot screws usually adjusted to the same number of turns or is it specific to each cylinder?
 

JUSTINTIME

Captain
Joined
Sep 2, 2006
Messages
3,284
Re: 89 115hp yamaha v4 cough erratic idle

i would rebuild those carbs and fuel pump
 
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