General tuneup

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lkrasner

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Jun 26, 2011
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This is the 3rd post about problems today, so hopefully its the last. I have a '95 johnson 115 that works okay but I know could run better. I am just wondering what some simple cheap things are that I can do to make it run more smoothly and better in general. This engine has seen some tough times, as it was sunk, blown up, and rebuilt. It idles like crap, especially when hot, which seems weird, should I adjust the idle speed? if so, how do I do it correctly? Thanks in advance for any help
 
1946Zephyr

1946Zephyr

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Oct 21, 2008
Messages
5,556
Re: General tuneup

I would take a compression test on it. Uneven compression can and will lead to a rough idle. As far as tune up goes, about all you can do to those is replace the plugs, gear oil and rebuild the carbs. The ignition is electronic and won't need your attention, unless something fails.
 
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emdsapmgr

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Dec 9, 2005
Messages
11,551
Re: General tuneup

The idle speed is set when the boat is floating, normally in the lake. The idle should be set between 650 and 750 rpm's, set when the engine is in forward gear. You can't set it properly on the trailer. The carbs have dedicated, small idle passages in the carbs. If these get clogged up with years of dried fuel, it just won't idle correctly. Once you crack the buttlerflys even alittle, the other jets supply fuel and the engine may run just fine at higher rpm's.
 
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lkrasner

Cadet
Joined
Jun 26, 2011
Messages
18
Re: General tuneup

How difficult is it to get at the carbs in this thing? I have never really taken one apart or tried to clean it, so how hard would it be? is it just best left to a mechanic that knows what the hell he's doing, or is it fairly straightforward? I already have to replace the rectifier/ regulator as I just found out, so I don't want to spend too much more as they are quite expensive. At least I don't have to take the flywheel off to get at it with this model.
 
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emdsapmgr

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Joined
Dec 9, 2005
Messages
11,551
Re: General tuneup

OMC made two completely different 115 engines this year. A crossflow type and a 60 degree looper type. Makes a big difference to our answers. If you don't know what you have, post the model number.
 
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