merc 115 powerloss

[izu]

During fishing trip my older 115hp merc starting running unevenly seeming to misfire, no power.Took it home and did the following the next day:
Checked spark while running seemed OK except cyl #3
Checked compression and got these numbers
#1 130
#2 125
#3 110
#4 125
#5 135
not enough space to access #6 may need a 90 degree adaptor! Then I ran deep creep through it,it seemed to work running evenly at idle for about 20 min then after trying a high speed run it began to run very unevenly again. So I talked to a friend who said "stuck piston ring on #3" fill cyl with marvel mistrey oil and wait. So I did it today. Long post giving U the details. Any help would be appreciated.

 

[Bob_VT]

Re: merc 115 powerloss

Soaking it with oil is a double edge sword. The design of the inline 6 2 stoke is a good one when running. Keep in mind anything you "loosen" up carbon wise when it is not running could get into the bearings and the reed valves.

If you can keep it running and use the mercury engine tuner or seafoam and do a proper decarb (multiple times) you should be able to free up the ring. The inlines used 2 types of pistons ...... some had 2 rings and some had 2 rings.

Follow the decarb proceedure in the FAQ section.

To get a compression reading on the bottom piston you can remove the bolts and the screws that hold that lower shield in place. It is a PITA but it will provide access.

The other main item is to look at the Link and Sync in the FAQ and that may help withh the idle.

 

[izu]

Re: merc 115 powerloss

that U much Bob VTl,will follow advice and get back to U...