running two stroke enginge (yamaha scooter) with fuel-alcohol blend?

[hacki72]

Hi there,
has someone experience in
running a two stroke enginge (yamaha scooter) with a fuel-alcohol blend? (85% unleaded fuel/15% Ethanol)
I think the lubrication could be a problem.
I also ask myself if the fuel lines can take it.

Thanks
hacki

 

[reidh]

A google search on this topic will show many similar questions to yours.

Reidh

 

[patprimmer]

With reference to the fuel lines. What answer did you give yourself.

My questions are:-

Why 15% ethanol when E10 is the common blend.

What are the fuel lines and anything else in direct contact with the fuel made of.

What is the fuel metering device and how can you corrct a:f for the different fuel.

Does your engine use a premixed fuel/oil or dos it inject oil into the crankcase.

Regards

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[hacki72]

Hi patprimmer, I try to answer the questions above.

First the blend:
I don't know what went wrong in my head (I was totally wrong!), but the blend they sell here in germany is a mixture of 85% Ethanol and 15% unleaded fuel with 95 ocante.

- The fuel lines seem to be ECO or NBR (very cheap one layer hose) I thought it would be better to exdchange them against a FPM/ECO/ECO or THV/ECO/ECO hose.

- Well I didn't really think about the fuel metering device but I don't have a idea how to correct it. But thats a big point if I don't want to be lost dry on the road.

- The engine injects the oil into the crankcase

I hope you can use these informations to help me.

Thanks
hacki

 

[patprimmer]

For 85% ethanol, I would use a fuel system rated for both 100% methanol and 100% petrol so far as seals and corrosion resistance goes. For corrosion resistance for a daily use fuel system components, I think the tank should be stainless steel.

Petrol needs about 14:1 a:f ratio.

Ethanol needs about 9:1 a:f ratio, so you need bigger jets or injectors or nozzles, lines, tank, filters, fuel pump etc, depending on required range and how engine is equipped. By fuel metering device I meant carburettor or fuel injection.

Use oil designed for racing with methanol fuel.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[JWaterstreet]

Many moons ago, I used to race small two-stroke enduro carts with various blends of petrol, methanol, and nitromethane. You probably have a Mikuni or equivalent carb that has a sliding throttle valve with a needle that goes in and out of the main jet assembly. You will need a much larger diameter main jet, and probably a different air mixer jet as well as the idle jet. I had the luxury of a head temp gauge to watch the mixture, without one is risky as alky mixes can run away on you quickly; in a matter of seconds. Back in the day, many racers used carbs that had both main and idle screw adjustments to be able to adapt quickly to different fuel blends and to dynamically change the mixture during the race.