1996 125 merc high idle

[kevinmac]

I have a 1996 merc 125 and when it is in nuetral it idles at around 1200 RPM's, when you put it in gear it goes down to 800 RPM's. What RPM should it be in nuetral I know it is not right now it makes a big clunk when you put it in gear because of the high Rpm and I dont want to damage the engine.

 

[schaiss]

Re: 1996 125 merc high idle

I know this will sound crazy but it sounds like your engine is running pretty good. The idle speed (in gear) should be about 700 rpm for that engine. The clunk you here is normal for the Merc engines built with a preloaded drive shaft. Your WOT rmp should be 5200-5500 rpm provided you have the proper proppeller pitch. Does the engine ramp up from idle to WOT without any problems?<br />By the way, the clunk is normal going into forward and reverse gears. As long as you maintain the LU with the right amount of lube (check lube for water and metal fragments - metallic slivers are caused by normal wear and tear). If you do want to drop the idle, it can be done with the engine at operating temp and IN gear. The idle screws on the carbs should be about 1 to 1- 1/8 turns out from their seats. Running a little rich (1-1/8 CCW) keeps those Merc 2 Strokes happy.

 

[kevinmac]

Re: 1996 125 merc high idle

The motor runs good going slow and fast but if I am going slow (1000 RPM's) and I push the throttle all the way down "WOT" there is about a 4 second delay before the motor goes higher in RPM's it sort of hesttates for the 4 seconds. At WOT she runs about 5200 rpm's.

 

[quantumleap]

Re: 1996 125 merc high idle

Those carbs have a tendency to load up if you mash the throttle all at once. Ease into it just a bit and it won't hesitate. When you gas it all at once, the bottom two carbs try to kick in a bit too soon.