Author Topic: ethanol  (Read 406 times)

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Offline patrickwhitty

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ethanol
« on: 29 Apr 2022 at 05:15 »
I think my Dragonfly may have an alcohol problem.
After initial problems when I bought it, the Dragonfly has always been incredibly easy to start, always first or second kick. Ignition on, fuel on, kick and away. I never bothered to tickle the float chambers. Until recently, that is. I run it through the winter, though much less than the rest of the year and tend to avoid night time riding due to the feeble lights. It has become incredibly difficult to start. Once started it runs well enough, but sometimes I spend so long kicking it that when it finally splutters into life Iím no longer in a fit state to ride anywhere. I end up going to work in the car, despite the horrendous cost of Putinís diesel, rather than face the battle of starting the beast again to come home.
Probably electrical. It usually is; 'most carburettor problems are ignition'. I cleaned the distributor, replaced the condenser, fitted a new coil, changed the spark plugs and changed my mind, several times. No improvement. I checked and re-checked the tappets, fooled about with the timing and gave the thing a good cussing. No change.
But clearly something had changed. And one thing was the petrol. It was running, or not, on a thankful of petrol from last October. Of course, petrol doesnít keep well. I re-filled it. No change.
Once it started it would cough and splutter and finally run. Short of fuel? Finally I tried tickling the float chambers to make sure there was enough and that simple remedy cured the problem. If I hold the buttons down until petrol appears then I can start it easily enough. Back to first kick starting.
The Dragonfly was converted to twin carburettors at some time in its past. Being bolted directly to the cylinder head they do get warm. Can it be that, with a little warming, the ethanol in the fuel is vaporising? The boiling point of petrol is 95C, that of ethanol is 72. The carburettors only reach about 20C but it could be enough. A hot summer day could have the same effect, but I havenít had the chance to try one of those yet.
I suppose it doesnít matter that much. I now hold the floats down long enough to see petrol before I try to start it. I might even count is an anti-theft device.
The explanation is easily checked. Without cleaning or replacing anything else I went 20 miles to the nearest filling station selling E5 petrol and filled it up, despite the horrendous cost of Morrisonís E5 petrol. And the result? Not always first or second kick but now it starts easily enough.
Odd it should make a difference. I was reading an article from an April 1947 edition of Autocar about four gentlemen taking a brand new 2Ĺ litre Riley RMB to Switzerland. It was so soon after the war that some of the bridges hadnít been re-built. On reaching Switzerland they filled the tank with Swiss petrol Ďon which full advance can be used because it contains 20% ethanol.í
Having overcome the alcohol problem, I now find the left hand cyclinder has started smoking.

Offline Hamwic

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Re: ethanol
« Reply #1 on: 06 May 2022 at 17:31 »
I have had issues with E10, and now only use E5, preferably Esso, BP or Shell. Apparently there are local differences in the blend, plus seasonal variations. I was told by an "inside man" at the local refinery that the combustion process curve with E10 now has a flat in it (?) as opposed to a steady rise in pressure with non-ethanol fuels. Make of that what you will. Apparently the E5 indication on Esso is actually "Up to a maximum of 5% ethanol" so might not have much in it at all.

I figured that as the car readout reckons I get 10% less MPG on E10 than E5, and that E5 costs around 6 to 8% more than E10, it's actually more economical to use the expensive stuff, and the vintage engines (M32, Velocette, Morgan JAP etc)  feel a lot happier on it too. I think a lot of people even with modern vehicles are coming to the same conclusion, and that it's all been a con, but who am I to say?...

Cheers for now
Doug

Offline EW-Ron

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Re: ethanol
« Reply #2 on: 06 May 2022 at 22:30 »
I think my Dragonfly may have an alcohol problem.
After initial problems when I bought it, the Dragonfly has always been incredibly easy to start, always first or second kick. Ignition on, fuel on, kick and away. I never bothered to tickle the float chambers. Until recently, that is.

I had a Commando like that - never failed to start first kick.
Put a rebuild kit through the carbs - and it NEEDED to be tickled AND choked, or it was no hope.
Must have been running rich as heck.

 

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