Super Unleaded Fuel

[Duccout]

Has anyone noticed, or does anyone know, if there is a difference in the fuel burn with Super Unleaded? Since we were saddled with 10% ethanol I have been running on the supposedly Super stuff, but it results in my plug electrodes showing a white colour, which is slightly worrying.

Does Super burn faster? And if so does it need the mixture adjusting, or the timing, or different plugs?

Oh for the days of good old four star!

Cheers,


Colin

[blethermaskite]

Colin, I think this is a really complicated subject I am running everything 'old' that I have on super unleaded simply on the basis that in theory it has the least ethanol blended in, in fact one major petrol refining company advised me that their super unleaded had no ethanol in it at all. When they removed tetra ethyl lead from petrol (completely erroneously on some half baked 'green' agenda) I with some trepidation started to use super unleaded with a range of 'quack snake oil' additives and it worked ok for me, I eventually stopped using the additives and again all seemed well without them.......so to date all seems ok with the two Ducati's.
However......the problems set in with my 1934 hill climb special competition car, it just didn't run quite right on any grade of unleaded petrol, I was advised by an engineer who knows more about aromatic fuels than I do that these unleaded fuels burn too fast for a vintage fairly inefficient long stroke motor.......and suggested I slow the burn down by adding a little kerosene (around 5%) per volume and there was an immediate return to the leaded fuel performance.
This for me has been a pretty unscientific journey mucking about with whatever that stuff they sell us as petrol nowadays so I can only offer my limited experience.
Cheers,
George

[George]

Hi Colin I have been using super unleaded, because of lower ethanol, for a couple of years with no problems. I did retard the timing on both bikes, my thinking is that the modern petrol is quick burn and by retarding timing brought ignition back to as was many years ago. No scientific knowledge on this but it works.

[Duccout]

My modern fuel-injected vehicles - Honda car and Ducati motorbike, both have the same colour on the plugs, a sort of yellow/ brown, but my old bikes have gone from a nice light brown electrode colour to white, and I don't know if I should try to richer the mixture up a bit. Still, I am not thrashing them, so hopefully it is ok.


Cheers,


Colin

[blethermaskite]

Try the next colder spark plug in the range of whatever make you are using before mucking about with the mixture and see what you get. That modern fuel burns hotter as well as faster, your plugs may just be getting too hot.
Cheers,
George

[graeme]

I think higher octane fuel burns slower than low octane.

Here in Australia we have 91, 95, and 98.
91 for most modern small engines (mowers, chainsaws, etc)
I’ve found 95 best for Ducati singles.
98 is too dense and therefore too rich.
BP and Caltex seem best.

98 works better if the compression is above 10:1 when jetted for such fuel.

Graeme

[themoudie]

If there is a choice available then I am using any 95 octane, E5, with Millers Oils VSPe Power Plus – Multi-shot added at 1cc : 1litre fuel, or EssO "Synergy Supreme +99 (E5), the latter is an E5 fuel, with additional octane booster. This is in the 1974 Ducati 450 MKIII, 1991 Yamaha SRX600 and the 1988 Honda Bros 400. When I was trying to get the 1979 Moto Morini 125H to run, with the Heron head, I was using these fuels as well.

If only 95 octane, E10 is available, I still use it and add Millers Oils VSPe Power Plus – Multi-shot added at 1cc : 1litre fuel. My reason for using Millers, is that it stabalizes the fuel, if I should have to leave the machine idle for any length of time (more than 4 to 6 weeks), it is economical in use at 1cc : 1litre and my local garage gives me a good price on the 500ml bottle that I decant into another measuring container produced by Briggs and Stratton for their garden machinery fuel stabiliser and fits in the tool bag.

If you are unlikely to leave a machine unused for more than 6 weeks, the additive might be a bit of overkill, as the fuel should be fairly stable, yet tend towards being hygroscopic, because of the ethanol. Any idle time longer than this then I would either drain the fuel from the carbs and fuel tank, or add the Briggs and Stratton/ Castrol "Classic" Lead Replacement and E10 Additives, running the engine, with the additive in the fuel to ensure that it passes into the carburettor. I usually, still drain the float bowl and leave it open to atmosphere.

All of the engines are producing a rich cocoa brown colour to the lower ⅔ part of the plug insulator and I find that they have a good "pick up" and steady running. I tend to run the engines a wee bit rich, rather than on the weak side, but the Ducati still has the occasional "spit back" when opening the throttle from the pilot onto the slide, when the weather gets hot. It's what happens when you run carbs and not injection systems, engine management systems etc. etc. etc., with E fuels.

Like George (blethermaskite) and recommended to me by Nigel, instead of using the NGK BH6S, as recommended by NGK, I am using the NGK BH7S plug and that has made a big difference to plug colour. With the NGK BH6S, I was always tending towards a white insulator, with a slight tan ring about a third of the way down from the nose and some slight blistering on the ground electrode tip. With the NGK BH7S there is no blistering at all and Nigel mentioned going to the cooler NGK BH8S when racing, but the 450 is only on the road.

If you really want to read up about the whole ethanol/fuel subject, then use the following link, it makes my brain hurt!

IEA-AMF_ethanol_properties_etc

Happy reading!

Bill

[graeme]

Yes, NGK B7HS or BP7HS with “P” being protruding electrode.
In all 3 x 450’s
Nice tan colour

[George]

Like Bill my preferred petrol is Esso supreme. To quote Esso website:
"Esso Synergy Supreme+ 99 contains zero ethanol, except (for logistics reasons) sites supplied from Scotland, North Wales, North England and Cornwall."
I also found NGK B7HS is the better plug in both bikes 1965 Elite and 1976 350 Road.

[Paul1098]

Esso will be adding ethanol to it's 99+ starting in September for all parts of the UK.