Modern Vespa

Hello there.
The UK currently has E5 Petrol and there's the occasional report here about jelly in carb when it's laid up for a few weeks.

Our major concern is today I heard we're going to have E10 petrol in September.

(Note to those who haven't been enlightened to the evil Oil Industry. E5 means 5% Ethanol added to petrol)

I know some Countries already burn this in their engines. My question is what effects it has and do we need to alter or change the following at least.
Jetting and Carb set up?
Ignition Timing?
Seals in the crankcase for what type of rubber?

Please save us from many breakdowns to come.

I've run E10 in my Rally for 12 years and never did anything special to it. When I replaced my fuel line during my engine rebuild it was hard as a rock and had shrunk. Might want to get a new line. Otherwise nothing special about the seals I have used, just whatever was available from Scooterwest or SIP. No issues.

You could just run a premium unleaded like Esso Supreme+ or Shell V-Power to be on the safe side. As things stand, they do not contain ethanol. For now it's just bloody expensive, although it's all relative!!

Here on the European mainland, E10 has been the norm for a couple of years. Most people I know with old vehicles just use the premium grade (Shell V-power, BP Ultimate, etc.) which is only E5. With the limited mileages we generally do with these vehicles, the extra cost makes little difference.

I hate the ethanol gasolines. Aside from destroying the fuel line, it leaves nasty deposits in your carb if you don't run the scoot on the regular. We have a few companies stateside that do ethonal free. You pay for it and have to drive to get it, but worth it the way I do math.

Ethanol has a lower BTU content than straight petrol/gasoline. Pure ethanol has 65% of the energy content of gasoline. At E10 you are 96% of the energy of pure gasoline, so not far off. Theoretically you'd up-jet a slight amount to compensate.

Back about 15 years ago I had a bike setup to run E85. I did notice gelling of the fuel because the synthetic 2T lube wasn't fully miscible in the alcohol. I switched to Castor based lube and that solved the problem. But that was a far more extreme case than you are facing as I had 85% alcohol. We routinely get E10/E15 around here in the midwest US and I haven't run across that issue with my current lube (Lucas Race 2T, which quick glance doesn't look like its available there in UK). I'm sure you all have others that are compatible though since E5/10 is so common.

The energy content is one thing, but the stoichiometric air fuel ratio is the bigger one, if you want to think about jetting


Fuel

Stoichiometric AFR

Pure Gasoline

14.7:1

10% Ethanol Gas

14.04:1

15% Ethanol Gas

13.79:1

E85

9.75:1

Pure Ethanol

9:1

The E10 needs less air-fuel, not more. So if you wanted the same afr relative to stoich you would down jet. You would have to put more fuel in to get the same energy out, but when we are tuning carbs we are really just tuning the fuel to hit an AFR, since the air is decided by how open the slide is. We often over-jet to with ~12 = use up all the oxygen and leave some hydrocarbons flying through. Trying to hit stoich on a non-emission controlled 2 stroke is not so useful and can land you in the lean zone = danger.

We have E10 in Australia... never used it!
We also have E85... tried it, blew up (crank pulley fell off, oops) my EG Civic due to far too many revs! Fuk it was worth it!

I have spoken to three scooter and motorcycle engineers about this and other than possibility of changing timing they did not consider this a worry. E10 has been available in certain parts of the UK for a while. Fuel lines on vespa should be checked each year anyway and yes ethanol believed to rot them but they used to go brittle before e5. It happened to me once when fuel was pouring from a ruptured fuel line on my px on to hot exhaust, was slightly concerned.

Worrywort you may be interested in this product https://lucasoil.co.uk/products/fuel-treatments/safeguard-ethanol-fuel-conditioner-with-stabilizers