Hitchcocks Forum

I bet this is a first. I put the bike back together with the old oil pumps. I emailed our hosts asking if they were happy that I put hi capacity pumps in without a pressure release valve on the rocker feed and they haven't replied. I took that as a sign and reassembled the bike with everything back the way it was before the rather expensive experiment with the pumps. Anyway, stupidly I hadn't properly marked the arrangement of the alternator wires and in the process of fiddling with them I obviously managed to generate a spark in the primary case. All that was in there was ATF but clearly having been around the block it was warm and there must have been vapour in there because there was an almighty crump and the cover just started pissing ATF. There is nothing wrong with the alternator windings and it is now wired properly and charging nicely but the cover is cracked and bent out of shape. Who new ATF vapour would be so inflammable?

You can see the smiling crack under the hole in the centre

That's nasty, Simon! I've heard of this before, but never experienced it myself. It looks like there could be a market for a pressure release valve to fit in place of the screw-in plug on the outer cover (like a pressure cooker.)

Simon, I've heard of this happening (from people who's opinions I trust,) but never seen it myself. It is usually where petrol has leaked into the engine oil from a flooding carb and the vapour ignites. Of course you know the high capacity pumps have nothing to do with this happening and I don't think the ATF is flammable either but I'm going to try and light some later just to check! I think what happened is that your outer case was over tightened in the past and just popped from stress. This is actually the real reason so many cases (Redditch ones usually,) are welded up, usually where the centre pillar meets the rear of the case. REgards, Mark

No no this was a very straight forward cause and effect. I carelessly flicked an alternator wire and there was an almighty bang and all the ATF poured out of the, until then, completely oil tight case (which did have a small dent but no cracks of any kind). Moreover it doesn't even fit on now as the sides have blown out. I agree that it has nothing to do with the oil pumps (that is an altogether different but equally sad tale). There is almost no chance that there was petrol in the ATF because there is no breather into the primary case on a Madras Bullet as there was on the Early Redditch ones. The ATF would have been warm and there was quite likely vapour from the primary chain churning the oil up and obviously enough O2 to make a combustible mixture.

I add that there was quite a lot of smoke inside the cover when i removed it and the bang it made was loud enough to bring the wife outside to see if I had done myself a mischief.

Hydrocarbon vapour,air, enclosed space, spark, = fuel/air bomb. It is why containers have to be chemically cleaned before any welding can be take place. (Even dust in the air can explode.)

Thanks for the explanation Simon, I'll add that to the (not very long, actually,) list of The Perils of Enfield Ownership! And you've saved me an experiment with ATF. The other example I have documented was a guy with an ex-John Surtees Connie where the case blew apart while riding although it stayed in place! REgards, Mark

So would I be correct that this hole in Tornado's plug is not factory spec then? (i.e., some guy drilled it?)