Tracker 50 hp high idle yamaha power head

opndcf

Recruit
Joined
Jul 11, 2011
Messages
2
Hi Folks,

I have a 98 tracker 4 stoke 50 hp (made by mercury) , yamaha power head
the motor had a really rough idle so I cleaned the carbs and fixed that issue
the motor will race up to over 2k at idle when I put it in neutral after running it
a little bit or alot it does it all the time . I've check the carbs and controls nothing is binding etc. I also checked the compression 150 + in all 4 and I checked timing due to the motor had the head repaired at one time so I let it run and put it in nuetral and the timing went from around zero ish to 25 + degree's advanced like wot timing so the only ting I can figure is teh CDI is messed up but I figured I would ask for some input. thanks in advance :confused:
 

opndcf

Recruit
Joined
Jul 11, 2011
Messages
2
Re: Tracker 50 hp high idle yamaha power head

me again , this only happens after the engine warms up , if I let teh engine cool it will start and idle correctly , only after its warm and I run in gear then put it back into neutral it will race up to 2k + and I'm sure its the timing thats changing the idle speed . I do have the manual and there are two heat sensors for the cdi one over temp and then on the rocker arm I beleive . I don;t have an issue putting a new cdi on but I want to be sure that I didn't miss something
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
Re: Tracker 50 hp high idle yamaha power head

I am not sure about your 4 stroke but on my 2 stroke there is a wiper on the CDI that is moved by the throttle linkage. That is what tells the CDI where the throttle position is at and that controls the timing. Maybe your throttle position sensor is going flaky, they are just variable resistors. Maybe yours is separate from the CDI
 
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