Merc 115 high idle

[Bob37814]

Hi....Newbie here, I have a 1979 115 s/n 5416341 My problem is when I start it it immediatly tachs up past 4000 rpm. It wil rev on up but never goes below that. another person told me they thought I put the stator on wrong when I changed the trigger, But it only goes on one way, The trottle plates are closed and the fast idle lever is completely down. the Link/sync is set, timing seems to be dead on(unless i messed it up by taking the flywheel off with the 8 bolts around instead of the main center bolt) Shes got me baffled tho, cant find a idle adjustment nowhere near the carbs...Just trying to get this one going since i got it in a good deal. Another thought on the matter is when I play with the lever that advances and retards the trigger, I can get the rpm down considerable, but How do you adjust it correctly?

 

[Barnacle_Bill]

Re: Merc 115 high idle

Double check your flywheel re-install. Manually turn the motor over until no 1 cyl is at the top of its stroke. Now check your timing marks, it should be pointing to TDC or very close.

 

[Bob37814]

Re: Merc 115 high idle

Bhile, I got it set dead on at TDC with #1 at the tip top of its travel......Seems like if I play with the spark advance I can get it to idle down a lot. Noticed there were 2 different screws on that, is one for idle adjustment or is it for the trigger adjustment....I noticed they both had something to do with the trigger mechanism. Would like to do a link and sync and was told Clams could help me but I cannot find his post in the FAQ on this forum....Hoping to get her running by the weekend, The fish are biting.

 

[Chris1956]

Re: Merc 115 high idle

What is the idle pickup timing set at? I believe it should be a few degrees ATDC.

 

[Barnacle_Bill]

Re: Merc 115 high idle

Yep, should be 5-7? ATDC with the idle stabalizer disconnected if you have one.

 

[j_martin]

Re: Merc 115 high idle

You need to do a link n sync from the git-go. I'd be willing to bet you mis-adjusted the trigger link when you put in the new trigger, but it would probably time up different anyway.
Can't just tell you how to do it. It varies from engine to engine, and each step is dependent on all preceeding steps being correct.

Do it right, or do it again, and maybe some major engine repair to boot.

hope it helps/