1991 Yamaha 85HP

[imported_vtwin]

Hi all,

My 1991 Yamaha 85HP is not equipped with an autolube system ,thank god, but is there anyone who can give me a decent advice about mixing the fuel?

My dealer told me this model Yamaha is an Endurance motor (??) and built for the 1:50 pre-mix. Another dealer says that all Yamaha 2-stroke models from the past 20 years can run on 1:100 mix, but only when using good quality oil.
I've tried the 1:50 and the engine runs great accept in the lower revs. It's shaking and smoking then..

Before I switch to 1:00 mix i'd like to hear some opinions on this, especially Rodbolts...
Which dealer is right, and what oil is the best quality?

 

[rodbolt]

Re: 1991 Yamaha 85HP

never seen any 2 strokes above 40 HP run on less than a 50/1 premix.
I see way more engine mishaps with premix than when using the precision blend. look for the actual printed oir ratio for a C85 and follow that.

 

[imported_vtwin]

Re: 1991 Yamaha 85HP

Okay, thanks Rodbolt.
I'm still a bit confused. The manual says 100/1 and you say you've never seen any 2 stroke above 40 hp run on less than 50/1 premix...

Is it safe to go on 75/1 when using full synthetic oil?
Right now i use Castrol Biolube TCW3

 

[rodbolt]

Re: 1991 Yamaha 85HP

I dont have your manual so I cannot say, if you premix at 100/1 then make sure you properly store the motor if not used more than 30 days and keep the cooling system in top notch shape, 100/1 is getting very lean on the oil side.
I did not say they never made an 85 desighned for 100/1 just I have not seen it, the list of stuff I have never seen grows daily .
and if you have the owners manual whats the point of the question? follow the manual and it usually works.
I have never tried the biolube so I cannot say.

 

[imported_vtwin]

Re: 1991 Yamaha 85HP

Maybe we have some different yamaha Models here in Europe?
Anyway, every better oil company sells in Europe their best oil as "biolube". This means that the oil is 100% synthetic and not harmfull for the environment...
Mostly every oilbox says it exceeds TCW3 oil quality and can be used in a 100/1 premix.

That is why i guess 75/1 must be safe..

For a few years ago i always used Pennzoil, but this isn't sold here anymore. Shell bought the Penzoil division overhere, and now this oil is "gone".
A shame, cause my experience with this oil was very good.
Now with the castrol oil i'have to wait and see...

 

[deejaycee_2000]

Re: 1991 Yamaha 85HP

50:1 is much safer ....