The engine:
Mercury 110 9.8 hp (? - that's what it says on the cowling), probably bought in Norway, with s.n. 90249**
Cowling looks like the Bluebands, has "Thunderbolt Ignition" written on it. Propeller has two blades.
Spark plug wires also have "Thunderbolt ignition" written on them.
There is a sticker on the power head reading "Kiekhaefer perma gap"
On the carb, I can read "Mercury" or something similar.
I aquired this engine one month ago, and I have used it for about 20 hours - just to see that it actually was working. Then I proceeded to cleaning up the cooling system (the indicator stream was very weak before I flushed thoroughly, in every direction, using a water hose and a vacuum cleaner), "changing" gear oil (salt water came out) and ... spark plugs. After having spent hours on finding what I thought were the correct spark plugs for this model, I bought and inserted a pair of NGK BUHW-2 (without side electrode) , only to find out that the engine only fired on one cylinder - the other cylinder worked very rarely and only at the highest rpms.
I originally wanted to change the plugs because the engine was difficult to start, requiring start gas every time. With the new plugs, the engine started quickly.
I re-inserted the old plugs, Champion L77 JC4, and with a warm motor, the upper cylinder works most of the time, but only on higher rpms, something that I didn't notice during the previous 20 hours I had the engine running. It was apparently working properly before my rather brutal attempt at flushing it.
I am suspecting either compression loss in the upper cylinder, or that both of these plugs are the wrong ones. I have not tried with a new pair of L77 JC4, because I cannot find any reference to it in Mercury manuals from the suspected production dates (1971 - 1976) Knowing the production year or the equivalent, American model would be a great help.
Could someone suggest what plugs I should use, or attempt to explain what I am experiencing?
Mercury 110 9.8 hp (? - that's what it says on the cowling), probably bought in Norway, with s.n. 90249**
Cowling looks like the Bluebands, has "Thunderbolt Ignition" written on it. Propeller has two blades.
Spark plug wires also have "Thunderbolt ignition" written on them.
There is a sticker on the power head reading "Kiekhaefer perma gap"
On the carb, I can read "Mercury" or something similar.
I aquired this engine one month ago, and I have used it for about 20 hours - just to see that it actually was working. Then I proceeded to cleaning up the cooling system (the indicator stream was very weak before I flushed thoroughly, in every direction, using a water hose and a vacuum cleaner), "changing" gear oil (salt water came out) and ... spark plugs. After having spent hours on finding what I thought were the correct spark plugs for this model, I bought and inserted a pair of NGK BUHW-2 (without side electrode) , only to find out that the engine only fired on one cylinder - the other cylinder worked very rarely and only at the highest rpms.
I originally wanted to change the plugs because the engine was difficult to start, requiring start gas every time. With the new plugs, the engine started quickly.
I re-inserted the old plugs, Champion L77 JC4, and with a warm motor, the upper cylinder works most of the time, but only on higher rpms, something that I didn't notice during the previous 20 hours I had the engine running. It was apparently working properly before my rather brutal attempt at flushing it.
I am suspecting either compression loss in the upper cylinder, or that both of these plugs are the wrong ones. I have not tried with a new pair of L77 JC4, because I cannot find any reference to it in Mercury manuals from the suspected production dates (1971 - 1976) Knowing the production year or the equivalent, American model would be a great help.
Could someone suggest what plugs I should use, or attempt to explain what I am experiencing?
