1983 mercury 115 I6 acceloration bog

[bcboy13]

Hey there I have a 1983 115 tower of power on a glastron 16.6 cvx with a 21p SS prop. When accelorating it has a devloped a bad bog. If given full throttle as if holeshoting it will just sputter and die. If the throttle is more graduraly applied it will get to 2000rpm+ and take off. It runs great at all other speeds but when trying to pull a skier or wakeboarder (or just holeshot) it will just die. It did not always do this so looking for some ideas. thanks

 

[Chris1956]

Re: 1983 mercury 115 I6 acceloration bog

If it used to work well before and not now, it is likely the carbs have gotten clogged.

 

[mr 88]

Re: 1983 mercury 115 I6 acceloration bog

I agree with Chris. Sometimes you can open the idle jets a touch and that lets you accelerate without the bog.Just have to make sure it does not affect your slow to idle speed. 21'' on a 16' and pulling skiers etc., sounds like it might be over pitched a bit,what kind of rpms are you pulling? Towers do not like to be lugged down.

 

[Dave1027]

Re: 1983 mercury 115 I6 acceloration bog

Rebuild carbs and fuel pump. Do sync & link and adjust idle mixtures.

 

[bcboy13]

Re: 1983 mercury 115 I6 acceloration bog

Top rpm is maybe 5200 just touching 50mph. It does seem alittle over proped for wakeboarding and such. Would like to try a 19p. I'm Gunna try to seafoam and spray carb cleaner in it see if it helps.

 

[orangeman]

Re: 1983 mercury 115 I6 acceloration bog

We had same problem with same engine. If the carbs aren't the problem check for water intrusion in the cylinders. If the top of a piston is really clean that is a sign of water intrusion(the piston gets steam cleaned). In our case the bottom crank seal leaked and water mixed with the oil that was then recirculated to the upper bearing which spun allowing the top of the crank to wobble ruining the power head.

 

[mr 88]

Re: 1983 mercury 115 I6 acceloration bog

Yes the 19 would be better if you are running a 21" that would put her right at 6 g's the sweet spot !! If I was boarding etc and had a couple of full sized people aboard I would get a cheap 17" 4 bladed prop ,aluminum,or a non dinged used one and use that when sporting,You must watch the tach at top end but boarding and in most cases skiing speeds are far from wide open.Pop's you out of the hole and maintains a steady speed a whole lot better...

Top rpm is maybe 5200 just touching 50mph. It does seem alittle over proped for wakeboarding and such. Would like to try a 19p. I'm Gunna try to seafoam and spray carb cleaner in it see if it helps.

 

[bcboy13]

Re: 1983 mercury 115 I6 acceloration bog

My max rpm is about 5200rpm not 6000. Is this normal? Top speed is about 50mph. Im going to try to find a cheap 18p alum to use for boarding.

 

[Chris1956]

Re: 1983 mercury 115 I6 acceloration bog

That boat is a bit overpropped. A 19" pitch prop would put you at 5600 or maybe a bit more. 50MPH is pretty good for that setup. Your prop slip is a bit more than I would expect, though.