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 I’m no longer in a fit state to ride anywhere. I end up going to work in the car, despite the horrendous cost of Putin’s 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 doesn’t 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 haven’t had the chance to try one of those yet.
I suppose it doesn’t 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 Morrison’s 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 2½ litre Riley RMB to Switzerland. It was so soon after the war that some of the bridges hadn’t been re-built. On reaching Switzerland they filled the tank with Swiss petrol ‘on which full advance can be used because it contains 20% ethanol.’
Having overcome the alcohol problem, I now find the left hand cyclinder has started smoking.
