Surface spark plugs NGK BU8H too cold?

[Scand]

Hello

Need some advice.

I feel that the surface spark plug type NGK BU8H is too cold for my use of the outboard. When I check the spark plugs, they are generally oily. Previously I was running both a little premix and the automatic oil system since I suspected the oil system was not working properly due to a consistent beeping. I looped the oil pump and only use premix today, but the spark plugs are still oily and wet.

The motor is also a bit sensitive to choke when starting. It´s easy to over-choke.

Engine No is OB349117, 1988 model. 135 hp Black Max.


Is it possible to use a standard spark plug with an electrode, or is it not enough space to the pistons?

Regards/Hansen (Sweden)

 

[Dukedog]

If it won't run right on those it won't run on anything else.....May be time for some maintance. Link n sync, timing, clean/kit carbs.. Compression check........jmo

Get tha "block off kit" for tha oiler. Mix either 40 or 50 to one.........

 

[Texasmark]

My Merc service manual for an '02 90 had surface and conventional listed. I tried the conventional and went back to the SG. Plugs are usually wet. One reason, besides the oil in the fuel is that to kill the engine you shut off the spark. So naturally, since the breathing process is still intact, fuel is routed through the cylinders and not exploded till the engine stops rotating.

A couple of years ago I pulled out the drive gear to my oiler and ran Penz. TC-W3 from WW at 50:1 pre mix. It's semi syn and even at the higher mix at idle (oiler puts out only 1:80 at idle, 1:50 at
WOT) making the pre mix more apt to smoke at idle, but it was unnoticeable.

My problem was CDI generated and once I fixed that I had no more ign problems.

My 90 didn't get run very often so it sat a lot between outings which caused it to be a little cranky on first startup. After that perfect the rest of the day.

Besides what Duke mentioned, might look at your starting procedures. Since you say it floods easily, maybe you are on the fuel enrichment (choke) too much. You do know that pushing in the key energizes that when the key is on. Do you run your fast idle lever on your remote up to set the rpms up when cranking? Is your engine vertical when starting, especially first of the day?

Just a couple of thoughts.

Mark

 

[Scand]

Hello

Thank you both for your answers. I only run 98 octane since the 95 octane in Sweden contains some ethanol which will make the gasoline absorb water and also prone to create acid, which may corrode the carburetors. I use the Quicksilver marine 2-stroke oil. But the previous owners; no idea.

I haven´t thought about the phenomena that the motor still rotates without a spark when ignition is turned off. So wet spark plugs are probably normal. Thank you.

I am careful when starting the outboard, only pressing the key after I have been cranking the motor a few seconds. But my son is not that...how should I put it....careful...he just want it to start even if it´s not in upright position.

Compression is approximately 120 PSi on all six cylinders.

It might just be the case that I need to do some maintenance before thinking about the spark plugs. The outboard is in the garage. So is all my tools. I also have some video inspection tools since I work in the NDT (non destructive testing) industry.

I, exactly like Texasmark, have the experience that premix 1:50 is hardly noticable compared with the automatic oiler even at idle. But it gives me some peace of mind to use premix. That oil beeping really annoyed me.

Best regards/Hansen

 

[Texasmark]

Maybe the son needs a little fatherly advice. Grin.

Before you get to worrying about other things, If you can obtain a product by the name of Sea Foam I'd like for you to try that. It is sold in autoparts stores here, Wallmart has it....guess they are there too. White pint can with red label. It contanins mineral oil, naptha, and alcohol. The label says to add 1 oz per gallon of gas or premix whichever for normal usage. For the first application, I'd put in the whole 16 oz can to 6 gallons of gas. Then go the 1 oz after that.

I have been using it since I heard of it on here back in 2004 and kept it in my gas as indicated. It works and it's job is to keep your fuel and cylinders clean. This is especially important in loop charged engines such as yours where there are only 2 compression rings and they are wedge shaped moving in and out on the combustion stroke and back to get the compression seal. If they are clogged with carbon they can't effectively do that. Also it keeps varnish out of your carbs and also serves as a fuel stabilizer, reducing the chance of stale fuel problems.

You're 120 compression numbers are fine per my service manual especially with all being the same number.

Good luck,
Mark