yamato 80 question

[wagner-racing16-s]

whats the oil to gas ratio for the yamato 80 i forgot to right it down last year and now i don't remember

[seanp3]

The user's manual calls for 25 to 1

[Smitty]

Yeah, but when was the manual written? Y-80s came to the States in about 1976, after they had been used for years in Japan. In those days, most 2-stroke oils were mixed "rich," clear down to 12:1 in some cases. But nowdays, most 2-stroke oils are mixed "lean," at anywhere from 40:1 to 100:1. This was done to minimize plug-fouling (which to your typical fisherman is a disaster comparable to a broken crankshaft) and carbon buildup. It is of no benefit to the 2-stroke racer, however. Modern oils can be mixed lean primarily due to the addition of an additive known as "bright stock." If you mix one of these oils rich, like your 25:1, the excess of bright stock can cause trouble, become gummy, as I understand it.

The answer is to use a real 2-stroke racing oil, as can be found in any dealership selling motocross bikes. Now in this country, due to the malign influence of lawyers, all businesses are terrified of product liability issues despite paying through the nose for liability insurance (making everything cost too much). Understandably, they play the CYA game. So, when you read the directions on the can of oil, it will say, "mix per manufacturer's instructions." The manufacturer has a more difficult choice. He would like you to run good oil, mixed per the oil company's instructions. But he has to cover himself for the engine owner in Lower Slobovia who is mixing carnkcase oil with his gas; the manufacturer's solution is to advise rich oil mixes.

[dholt]

Rick,

If you're using non-synthetic...run it 8 or 10 oz. to the gallon. That's what I run.

If using synthetic, you could probably go to 6 oz. per gallon.

[jsilvestri]

If using synthetics, go by the manufacturer's mixing ratio. I use Klotz synthetics in all of my engines, which includes Yamato's, Merc.'s and if you over mix, the cylinder walls will get a glaze on them not allowing the piston rings to seal properly causing a loss in horsepower. Been there with that. If using conventional oils, mix accoding to Dana's post.