Off Topic 20HP Yamaha

E

EMeadus

Active Member
Fellas,

I have a 1994 20Hp Yam on my boat and the oil to fuel is 100:1 which to me seems a bit rich. I've had 2 stokes before and mostly mixed at 50:1. 100:1 is only 200ML of oil to 20L of fuel which doesn't seem like a lot to me, I know that's what Yamaha asks for for fuel mixture but I'm wondering has anyone done anything different, say 80:1 just to be safe or should I be fine sticking with 100:1. I know if I mix more oil I run the risk of fouling plugs and such but it just seems like very little oil that's all. So i though Id ask the pro's here lol. What is the members thoughts on this?

Ed
 
A 100:1 mix is lean not rich. I had a 1986 Yamaha 30 hp 2-stroke I ran on a 14 1/2 ft. Lund for 21 years used for both small lake fishing and some moose hunting. I always ran the Yamaha required mix of 100:1 with zero issues. Running any richer will only foul plugs while choking you unnecessarily with smoke. ;)
 
Great advice here guys I can’t thank you enough. The few trips I have made with the boat I have run exact mix 100:1. I have a 24L tank so I only mix 20L of fuel at a time which also makes it easy to add the right amount of oil.

I will start cleaning my plugs after every big trip as to avoid hard starting as sueggested ?
 
EMeadus said:
I will start cleaning my plugs after every big trip as to avoid hard starting as sueggested ?
Click to expand...
It's up to you and it certainly doesn't hurt anything to do so but I just change the NGK plugs at the start of the season each year the same as I do now in my Honda outboard. The 100:1 mix in my Yamaha never fouled the plugs in all the 21 years I ran it even after many hours of slow trolling. When I opened it up to full throttle (which was always) coming in after fishing it blew any accumulation off anyway and even when I sold the boat it was very rare it wouldn't start on the first pull. Also it is easy to fill your 24 liter tank accurately, you add 240 ml of oil for 100:1 mix. If topping up just remember it's always 10 ml per liter of gas, easy.

NOTE: If you want even better oil protection I recommend full synthetic over any of the conventional oils out there. Other than the higher cost it has only upside advantages. It will improve every operational aspect of your engine while giving off far less exhaust smoke, keep spark plugs cleaner, reduces engine friction, gives improved wear protection and better throttle response as well as easier starting in cold weather. I run nothing but full synthetic in any engine 2-stroke or 4-stroke and have never had a single engine failure. Good luck boating this season! :)
 
When you are talking 2 strokes less oil is a richer mixture. Any time you displace fuel whether it is air or oil or anything else you are leaning out the mixture. I have had customers in the past that confused that theory with race motors that we built for them.
Adding oil is simply adding more oil for lubrication purposes and should not be confused with the fuel mixture that the motor requires!
We liked to run more oil for lubrication purposes but then would have to richen the fuel mixture to compensate for the additional oil.
I do agree 100% on the above with regards to the synthetic though. The mineral based oils will leave more deposits that foul plugs and simply cant compare to the synthetic for providing the lubrication properties at those low oil mixture ratios. Also dont confuse semi-synthetic with the full synthetics.
 
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I run full synthetic in everything I own that burns gas. When I first run the engine for the day it takes about 4-5 pulls and it will fire right up but the rest of the day its one pull only. This outboard I got for $700 with tank and furl line inclued which was a hell of a deal I think. Its been well taken care of thats for sure.

When I say I mix up 20L batches of fuel its because I use the fuel pump at the gas station to know when I've pumped 20L exactly which allows me to be very accurate when adding my oil.

Thanks again guys.
 
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