Smokin 2 Stroke

I Have A 1977 Merc 1750 (175 Hp) That Starts And Runs Great, But Smokes Like Crazy. I Mix Accurately At 50:1. I Have Tried Penzoil Synthetic Blend And Walmart Oil. Both Seem To Smoke Just As Bad. Can I Try 60:1 Or 70:1 Without Frying The Motor? I Am Getting Tired Of The Strange Looks As I Am Going Down The Lake.

Thanks

 

She burns what she burns,. If it is supposed to run on 50-1 then do so,. However I think it will be your mixing, --accurately yes,-- correctly no.

Re consider your method of calculation. they were a bit smokey the old motors but not that bad as to attract such attention to yourself.

You should however ONLY use marine 2 stroke oil.

 

Try a compression test n see if some new rings or pistons are in order,curious what answer u came up with,i think synthetic oil at 50 to 1 is good but wore out motors well smoke.

 

Ron - Do you think that some new rings would stop it smoking?

If synthetic oil mixed at 50/1 will wear out your motor --why is it good?

 

Flyguy - the obvious question: When did you last de-coke the engine. Two-strokes are pigs for oiling up - whiskers on the plugs- and clogging exhausts.
Mind you I'm only talking from motorcycle experience - and that briefly (rapidly switched back to four-stroke).
Smoking despite 'correct' mixture - then backpressure in the clogged exhaust may be your problem. And experimenting with a thinner mixture won't do any harm. The cause may well be a build-up of 'residual' oil in the crankcase adding to an already 'too thick' a mixture.

 

You first have to figure out if the motors wore out,(needs pistons or rings)no matter how you mix the oil n gas it wont fix a motor n need of repair,ive read about very lean mixtures,but 50 to 1 is as lean as id want to go,and i think pure synthetic oil is the best.you could have a broken ring.

 

Bergalia is nearer to an answer than the piston ring proposal. If the rings and or pistons are worn badly the engine will have less compression with somewhat less combustion chamber capacity to burn the fuel/lubricant mixture. That does not necessarily mean that it will smoke. Smoke implies that some oil burning is taking place. Premix goes through the carburetor across some reeds and into the crankcase. From there it goes through the intake ports to the combustion chamber. On the way through the crankcase it lubricates the crankshaft main bearings as well as the connecting rod bearings. If you make the fuel/oil ratio any bigger, like 70:1, you risk engine destruction.

Use two stroke oil only. The presence of synthetics may be part or all of the problem as synthetics have different burn rates than dino oil. There is a web site, Bobtheoilguy.com, who dispenses a lot of intelligent information about oils. Try consulting Bob.

 

Easy to just see what the compression is,and as to the synthetic oil,it is superior to conventional oil,would take to long to explain,ill just say if 2 motors from when new used each type of oil id almost guarantee the synthetic oil motor lasts much longer.superior ability to lubricate when cold,wich is where a lota damage occurs.you may try having your motor pressur tested n see if you have a blown seal.My ring and piston expierience is from dirt bikes wich smoke more n more as the engine wears,easy to figure out when u need to freshen the motor up.

 

Ron this is not a diesel like you have in your trucks. 2 stroke diesels are not the same as a 175 hp merc.
The only oil in the engine is what you mix into the fuel. If you have too much oil and therefore smoking its because you put it in there.

2 strokes should not smoke, look at those indoor dirt bike stadiums, Jeeesus you would think people would be running from the building with stinging eyes after 10 minutes.
50/1 is not lean mix Yamahas have had 100/1 for years. And now with automatic oil injection that varies oil input into the carb at different requirments of throttle application. Thats not new iether.

The most common problem -- well the only problem of 2 strokes smoking is incorret mix or injection pump adjustmen

 

Jack u made me rethink,yeah the oil past the seals thinking is wrong but ive never ran anything at 100 to 1,even at 50 to 1 you should have little smoke unless u idle alot and let the motor get loaded up,but outboards would seem to be screaming along most of the time,so im not familiar with oil injection,most people removed in in years gone past since it tended to fail then the motor would run lean with no oil and die.Jack modern 2 strokes with synthetic oil smoke very little if at all.i base my premix thinking on an article written by a pro dirt bike racer who raced 2 stroke go karts and of course my years of riding and racing with no problems at all.If your outboard is warmed up and still smokes on down the lake u would think it would be something else than than premix ratio,mabe empty n clean the fuel tank n clean out the carb.Oh yeah, modern diesel big trucks smoke very little also.

 

I once worked out just what 100th of a liter looks like. I finally used the ubiqutous camera film container, mark of .5 inch from the bottom,-- that is 100th of a liter. Not much is it?

And thats the problem -people say "naaa that cant be enough I dont want to fry the motor and give one more for the pot,-- which will double it.

Then they dont empty the tank fully. So off to the gas station --one for the pot and it gets worse and worse.

 

Been guilty of that! And to make things worse always liked to keep the tank almost full so it was regularly getting the "extra drop"

 

Smoky and the 'bandit' two stroke.

I believe it is better to finished off the lube oil mixed fuel before topping up. My experience is mainly with portable tank though.Quick silver 50:1 by Mercury is the best for Mercury engine, but if the mix ratio run towards more lubricant it still will smoke real bad. 70:1 or 100:1 is not for you type of engine.If your engine used lube injection, than using 50:1 oil for that purpose is wrong. It will smoke like crazy! Any ordinary two stroke lube oil will do for lube injection system. Normally 2 stroke ouboard marine engine does not have as much coke as motorbike engine, but still cleaning the head and piston crown will give a better performance compared to not.

 

You need to make sure whatever oil you use is designed to be used with Outboard engines. Air cooled two cycle oilr will not burn completely and will cause excessive smoke and piston coking.
If you are using marine two cycle engine oil, then the main cause of the start up smoke is due to the fuel in the carbs evaporating when you let it sit for a couple days or more, The oil will not evaporate out of the carb bowls and when you prime the engine, more oil mixed fuel enters the carbs giving you double the amount of oil at start up. There is no way to escape it.

 

I little extra oil momentarily on start up aint such a bad thing.