Time to get new spark plugs? Or not

[captpierre]

Winterized my 2007 Yammy 115 4 str.

 

Oil very dark (as usual). Lower end lube like new.

 

Pulled the plugs to spray the cylinders.

 

As usual they look great. No fouling.

 

After 5 seasons still the original plugs. Likely 400 hrs total.

 

Are new plugs needed or do I keep going?

[BillM]

If they are working fine, I wouldn't touch them... There's really no point.

[DRIFTER_016]

Yep, if they look good just leave 'em.

[2 tone z71]

I change mine once a yr..usually spring after i Burn the fogging oil out of it...cheap insurance

[DanD]

I would check the service schedule from the manufacturer.

Any spark plug after some use will require more voltage to ark the gap. This higher voltage will put a strain on the ignition coil(s) and secondary wires; which could cause them to fail prematurely.

For example if an ignition wire is burnt open due to high resistance of a spark plug; the secondary voltage could back feed the ignition system looking for ground and take out the control module.

 

 

Dan.

[Garnet]

Go to your local auto parts store to buy your plugs. Much cheaper than a marina.

[Bernie]

I'd say with 400 hrs on it that it's time to change them.
DanD is right.

[jimmer]

I'd say with 400 hrs on it that it's time to change them.

DanD is right.

So, changing them once a year is a good guide if we use a boat regularly??

[2 tone z71]

So, changing them once a year is a good guide if we use a boat regularly??

whats it gonna cost ya to get towed in...or loose a days fishing ...for what 20-30 bucks..change em yearly

[aplumma]

I change them yearly and carry the old set in the boat as backups.

 

 

Art

[misfish]

I change them yearly and carry the old set in the boat as backups.

 

 

Art

 

 

I'd say with 400 hrs on it that it's time to change them.

DanD is right.

 

No harm,no fowl.

[Bernie]

Each engine will have it's own way of using up spark plugs.

Lots of trolling/slow running would be harder on a spark plug on some engines due to a colder running engine. This could make for some incomplete combustion and deposits on the plug.
Older 2 strokes would tend to foul plugs before they would wear out.

Today's engines run a whole lot cleaner due to better fuel control and better oils for 2 strokes. This allows for longer lasting spark plugs.

 

I have seen some great appearing spark plugs that are no good. The porcelain insulator that surrounds the electrode can accumulate a film from fuel and oil that becomes a conductor. This conduction will cause the spark to follow down the side of the insulator and go to ground rather than jump the gap.

 

I can tell when my engine is due for plugs. It runs a little rough on cold starts.
If you run an engine that only uses 2 or 4 plugs, change 'em every year anyway, what the heck is a couple plugs for peace of mind?

 

Fuel injected engines should be able to get a couple seasons before replacing. These engines run cleaner than most.
As always, check your owners manual for it's recommendation.

[captpierre]

thanks Guys.

 

I'll check the manual. I suspect it will say replace

 

Maybe wait till a run in the spring after the cylinder spray has burt off

[aplumma]

I guess I should clarify why I change them yearly. I am running a 1989 6 cylinder johnson gt 150 hates to cold start, smokes on the warm up and runs like a scalded dog all day long. The carburetors on theses beauties are 3 float bowl 6 barrel with fixed jets. Needless to say it runs from really wet down low to perfectly balanced as you run up the lake. I need all of the spark I can get for the soggy lower RPM,s. It is a love hate relationship if it gets out of tune it is a cranky pants motor but when it is right it will paint a smile on anyones face that runs up the river with me.

 

Art

[DRIFTER_016]

My old '91 Merc 90 2 stroke I would foul plugs occasionally.

I would clean them up and be good to go.

I kept several sets in the boat so if needed I could spend a couple of minutes changing them and be good for the rest of the day.

I am still running the original plugs in the rotation!!!

Well, was until I bought a shiny new 115hp 4 stroke this past spring.

[Roe Bag]

Pulled the plugs to spray the cylinders.

 

As usual they look great. No fouling.

 

After 5 seasons still the original plugs. Likely 400 hrs total.

 

Are new plugs needed or do I keep going?

My Mercury four stroke manual recommends changing them after 300 hours.

If the electrode is not deteriorating from the heat just make sure the gap is correct. Over time the heat will melt the electrode tip. It will round over on the edges and shorten in length. This will alter the gap resulting in a lack of performance.

Two strokes are prone to fouling because you are constantly burning oil within the combustion chamber.

The only time there is oil in the combustion chamber of a four stroke is if you put it there (winterizing). Or, if you have a serious problem like worn piston rings or scored cylinder walls.

Over time you may see carbon build up on plugs installed in a four stroke which can be easily removed with a wire brush.

You should never see oil.

 

kwikfish.

[Bernie]

Not all 2 strokes have oil in the combustion chamber.
Direct injected ones do not.

[Roe Bag]

Not all 2 strokes have oil in the combustion chamber.

Direct injected ones do not.

 

So the question is, how is a direct-injected 2-stroke engine lubricated? It cant use a sump system like a 4-stroke because the crankcase is still acting like an air compressor. And you cant mix the oil with the gas as in a traditional 2-stoke, since the gas never makes it into the crankcase. An E-TEC engine uses an external oil tank that holds about 2 liters of oil enough for about 40 hours of engine operation. The oil is slowly injected to places like the crank bearings and cylinder wall. Therefore, the oil does mix with the air getting pumped through the crankcase. It gets burned in the combustion process. The amount of oil is so small that it has no noticeable effect on emissions, and it has none of the pass-through problems with oil as in a carbureted 2-stroke. Also note that, by burning the oil, there are advantages. There is no pollution potential when changing the crankcase oil of a 4-stroke engine (e.g. person spills or dumps oil on ground or water), and there is no possibility of forgetting to change the oil and ruining the engine.

 

For the rest of the article see: http://blogs.howstuffworks.com/2010/11/08/the-direct-injection-2-stroke-engine-all-the-advantages-of-a-two-stroke-none-of-the-disadvantages/

 

kwikfish.

[aplumma]

Sometimes it is necessary to simplify a statement so everyone can grasp a complicated mechanical process and to avoid a wordy explanation. With the wealth of knowledge that Bernie has and shares with the community, given my choice I am sure Bernies answer was sufficient for 99 percent of the members.

 

 

 

Art

[Roe Bag]

Sometimes it is necessary to simplify a statement so everyone can grasp a complicated mechanical process and to avoid a wordy explanation. With the wealth of knowledge that Bernie has and shares with the community, given my choice I am sure Bernies answer was sufficient for 99 percent of the members.

 

 

 

Art

 

Really not sure where this is coming from.

No ill will intended on my part.

Simply offering information that supports my previous post.

If you see it as anything different, I'm sorry sir but I can't help you there.

 

kwikfish.