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Spark plug condition

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Re: Spark plug condition

Postby mattswan2512 » 16 Nov 2017, 17:16

Yes mate i do lol :thumbsup but as its part of a service kit ill remove them clean em up and keep them as spare... spares lol
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Re: Spark plug condition

Postby The Hobbit » 16 Nov 2017, 20:04

A genreic question initialy but you 2 stroke experts please dive in particularly Martin as I believe "The messershcmit" is older than mine. I have a 2 strole Yamaha 15D apparently dated 1985 according to the serial number. She's a beaut. But on the mixture side of things..... what SHOULD I be running it at? To date I have run it at all 3.......... 100:1 50:1 and 75:1. All seem to be fine but can't make my mind up. After a lying up period I tend to run it 50:1, after some good running I change it too 100:1......... still can't decide what's best sometimes so I run it at 75:1. Any experienced guidance would be appreciated and hopefully may solve Matts questions too. :drive
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Re: Spark plug condition

Postby chris moody » 16 Nov 2017, 20:12

I'm definitely no expert. On my 2 stroke (Tohatsu 9.8hp) the manual said you run it at 25:1 while running it in (first 10 hours), then run at 50:1. After a winter layup run it at 25:1 for the first outing, then revert to 50:1.

I've just finished running it in, and surprisingly it was less smoky at 25:1 than I was expecting it to be (I was expecting a smoke trail and oil slick to be following my wake)
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Re: Spark plug condition

Postby mattswan2512 » 16 Nov 2017, 20:26

If your unsure id run it at 75:1 andy as its the happy medium. I have had a quick google and yams of 1990's to early 2000's run 100:1.

I think its wise at the start of a lay up period to run it at 50:1 for a few hours but then unless heavy use drop that off a bit. I honestly think my OB runs sweetest on 100:1 bit if its gunna get a thrashing then mix in a bit more. It can get your engine gunky and messy but oil is there for a reason and as long as you dont go overboard as this can cause as much damage as none ull be fine.
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Re: Spark plug condition

Postby Andy B » 16 Nov 2017, 21:25

Right,
I think i need to put a couple of things straight here....

Firstly.
Matt your engine should be run at 50:1. I wouldn't go messing around with different mixes.
The reason is that if you add more or less oil it affects the consistency of the fuel/oil mix making it harder or easier for it to pass through the jets.
Adding too much oil can cause the engine to run lean as it's harder for the fuel to pass through the jet. (Not richer)

Adding more oil while running in is advised to aid with the bedding in process. but the reason you don't over rev the engine at this time is so as not to scorch the oil and burn the inside of the engine.
Chris the reason why it seems more smokey now is because it's now burning all the oil in the mix where as before it wasn't able too.

Matt
The reason that you are not getting a clean burn in the water but has nothing to do with the mix ratio, it's down to heat.

(are you using Marine 2 stroke oil?)

The main difference between Marine 2 stroke oil and automotive 2 stroke oil is mainly the burn temperature.
Marine 2 strokes run at much lower temperatures than lets say a scooter because they are feed with a constant flow of cold water.
there are other subtle difference and additives, but that's the main one.

enzo200500 wrote:You really need to run the engine under proper loading conditions to get a true idea of mixtures etc.

What he said
To get a true result you'd need to either run it on a boat or in a test tank with a test prop fitted.
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Re: Spark plug condition

Postby mattswan2512 » 17 Nov 2017, 08:15

Hi andy.

After reading the manual and its even got a sticker on it saying it its deffo 100:1 for this engine mate according to manufacturers specs.... In the book it states 100:1 leisure and 50:1 commercial use? is it better to run these on 50:1 then as that is what i did for scotland and it would not run correctly mainly due to crud in the carb or debris in the fuel i think......on my last run out i mixed at 50:1 and you could really smell the fuel and oil heavily and same issue.

I have eliminated the fuel, tank, carb cleaned again by mechs and found to be in fine fettle (apparantly)

Im hoping to get out and test today on 100:1 as per the sticker on the handle and the book to see what happens.

Yes its marine grade oil i am using it came for free brand new & sealed with the engine mate.
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Re: Spark plug condition

Postby Andy B » 17 Nov 2017, 08:41

Ok, maybe I'm getting confused here.
We are talking about a 15hp merc/mariner here?

Older yams used to run at 100:1

Bottom line is do what the manufacturer says mate.
They built the engine, so it's safe to assume they know what it wants...
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Re: Spark plug condition

Postby mattswan2512 » 17 Nov 2017, 09:10

Yes andy mercury mariner but in the early to mid 2000's they were changed over for a period to 100:1 those that were have been clearly stickered and it sais in the book but the books headline figure is 50:1.
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Re: Spark plug condition

Postby The Gurnard » 17 Nov 2017, 09:39

Hi Matt ..I admit I'm not an expert on OB's but I know my Mariner 25HP from 2005 is supposed to run on 100:1 ..it has its sticker and also instruction manual saying so. I believe it is a rebadged Yamaha as that was common in those days ?

Like you..I run it 75:1 or there abouts. I never have an issue with carburation..it does smoke when cold but it does that regardless the mix. I don't do accurate oil measures either ..just slosh slightly less than 100ml oil looking at the scale on the oil bottle..into a 5 litre petrol can I transport the fuel from the garage in. It actually holds 6.5 litres .. which is why I say 75:1 lol. My OB has done thousands of hours..no issues..so I think you are doing ok with your mix. As mentioned..Im no expert only telling my experience. A couple of comments were made at WWA on how easy it started and how well it ran. If I'm skint its 100;1 to max my money ..so I'm not so sure its as critical as suggested.. anywhere between 100 and 50 to 1 suits me.

NB..this is only if the OB is designed for 100:1 if unsure I would use 50:1 as in my 3.3HP Mariner which has no sticker and the manual says clearly 50:1
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Re: Spark plug condition

Postby Martin » 17 Nov 2017, 09:59

The Hobbit wrote:A genreic question initialy but you 2 stroke experts please dive in particularly Martin as I believe "The messershcmit" is older than mine. I have a 2 strole Yamaha 15D apparently dated 1985 according to the serial number. She's a beaut. But on the mixture side of things..... what SHOULD I be running it at? To date I have run it at all 3.......... 100:1 50:1 and 75:1. All seem to be fine but can't make my mind up. After a lying up period I tend to run it 50:1, after some good running I change it too 100:1......... still can't decide what's best sometimes so I run it at 75:1. Any experienced guidance would be appreciated and hopefully may solve Matts questions too. :drive


In regard to Hobbits question :- ratio
My 1978 DT manual quotes 30:1 for run in period and then 50:1 if using suzuki CCI oil or any other BIA certified lube. If not certified use a ratio of 30:1

I now run it at 50:1 as I advised Matt when he borrowed it on the WWA. He was running 100:1 so he adjusted his tank to suit.

Matt, get your feeler gauges out and gap the bloody plugs :Boxsmile

In general regard to this post and the questions around it..
here’s my take.
Outboard oil is different to any other two stroke oil as it needs to burn at lower temperatures. This is in general user form- Always in the water your outboard will not run at the temperatures a land machine runs at, ie- an outboard won’t hit the temps a stihlsaw runs at. Therefore specific blends are made for marine. Anyone that tells you different is talking out of their backside. Don’t take my word for it, ask the guys line I asked at shell.
Outboard blends differ from manufacturers, only generally sold under the outboard manufacturers name but produced in reality by a number oil blenders.
I deliver baseoils and brightstock to Fuchs, Rockoil, Lubrizol, Shell, Castrol to name but a few and they will all have specific blends to their name. As long as the two stroke oil meets the generic (and later) specification of TC-W3 it’s suitable for use in watercooled outboards.

Use the oil recommended by your outboard manufacturer, use it at the correct ratio, if it smokes or deposits too much then look at swapping blends as long as it meets the spec recommended.
I’m a huge shell fan, they put a lot of time, effort & expense into their fuel/oils & lubes and I think there’s many on here that after following my fuel advise wouldn’t swap back to cheaper stuff.
It’s all in the additives guys, oils & fuels all have different make up of additives !!
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