115 hp merc

[runningbear888]

Could someone tell me if they have come across this problem? Mercury 115hp 1976, timing set at 21 degrees, fuel is syncronized with timing as according to manual, new fuel pumps, carbs were cleaned, Seafoam ran through it. The engine, when taking off from a stand still, takes a few seconds to jump up on plane. Once going speedometer reads 25, sometimes 28 mph. I don't have a tach gauge but I know the engine isn't getting up to high speed rpm which is around 5200. When trying to pull a tuber or skier it takes a long time before it planes out. Compression is all good at 130 in all cylinders. Is there any chance that it could be the stator under the flywheel and could there be a test put on it to determine it to be faulty? The book doesn't say much on it. I do have spark at every plug and new plugs were put in it.<br /><br />Thanks for your time and response.<br />Runningbear.

 

[ZmOz]

Re: 115 hp merc

You really should have a tach of some sort. Could be that you don't have your motor trimmed out right. I have an inline 150hp and if I don't have the trim set right it won't get up for a good 5 seconds.

 

[runningbear888]

Re: 115 hp merc

thanks oz but i've tried every trim setting.

 

[dvchristoff]

Re: 115 hp merc

I have the same motor and was having the same problem when towing. Went from a 21 to a 19 prop. RPMS went from 4600 to 5000 and boat hops right up on plane. Big difference in performance. I have been told the tower of power likes to spin. Do not bog it down, can cause powerhead problems.