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[stinkwheel]

I did (and completed!) my first long distance trial on my 2007 350 bullet today.

The many varied inadequecies of the build and rider notwithstanding, I did have a particular issue. When going over an abrupt down incline (so say a 2ft drop into a ford), the engine stuttered and conked out.

It did the same thing 4 times. Three times dropping into a ford, leaving me to restart in the water and once on section dropping into a gully. If I was on a mountain bike, I'd have called them "drop-offs". The last time it happened, I conciously gave it more gas as I went over the edge (which is not what I really wanted to be doing) but it still did it.

I'm totally convinced the water was not a factor, it happened too quickly and I went through WAY deeper water today with no problems. In fairness, I probably went down much steeper inclines too, it seemed to be the sudden downslope that triggered the behaviour.

I'm thinking float height and the possible solution is to up it a little or even make a manifold with a slight down-angle so the carb sits more level when on a downslope. It has a standard mikcarb jetted to suit a pod filter and trails pipe. Running a little rich if anything.

Just wondering if anyone else has experienced similar issues?

[Daiwiskers]

Could be wrong but to me it sounds like it's a bit weak on the pilot
I know that it did it with throttle slightly open but presumably the throttle was closed and on the pilot before and then opened on the drop itself

Could be float level I set Japanese carb floats so the float sits level in relation to the side of the carb (hope that makes sense)

Sure you will get it sorted Dai

[Daiwiskers]

Too late to edit

Just had another thought could it be float level too high causing it to flood as you go over the drop and also being the cause of the over rich running at other times

Dai

[Bullet Whisperer]

It sounds like it could be electrical to me, are there any wires or connections getting disturbed going over the drops and briefly shorting or disconnecting?

[Presto]

Neither float height nor pilot circuit is likely to cause an instant stall in the exact same situation. That you increased revs and still stalled seems to rule out a simple low revs stall. Water isn’t a factor. Electrical may be – but to be such a consistent fault isn’t usually in the nature of an intermittent electrical problem. Gravity may be.

I would suspect momentary fuel starvation. Not due to fuel level or weak pilot but gravity.

Only a theory.

[vince]

Hi, how long a drop was it? I ask because with the tap at the back of the tank it may momentarily starve of fuel on the way down. Vince

[Presto]

A couple of questions:

1. I guess you descend this drop front wheel first, as you say at a steep angle?
2. what carburettor is fitted?

[Daiwiskers]

See my sig
Do you have heavy keyring? I did notice that you have a lanyard stop fitted could it have been pulling as you went over the drop?

[stinkwheel]

Standard mikcarb fitted. Yes, front wheel first down into the drop.

I actually stopped using the lanyard stop because it doesn't pull off with a minor spill. I got it all tangled round my legs when I came off on one section so I was stood up and the bike was on its side still running. I decided it was more of a hazard than it was a safety device.

I should say that the bike fires up first kick after these cut-outs, further removing the likleyhood of water causing the issue. It did conk out when I soaked the air filter later on in the day and took quite a bit of re-starting after (thank goodness for decompressor valves, a wee insurance for if you are worried you might have drawn water into the engine).

I'll look into the electric side. I deliberately kept it very simple and very robust. Plenty of extra cable for tension relief and such. If there's a weak point, it is the ignition switch... I'll have a look at the ammeter post connections too. Not too much to trouble-shoot in that respect in any case.

I don't think it's the actual fuel flow into the carb, it'll go a good couple of hundred yards on the contents of the float bowl.

It's a tricky one to go out myself and try to replicate. I certainly don't want to be looking at the ammeter when it happens!

Maybe lower gearing will sort out the issue too, if i'm geared lower, there will be higher revs (through simple forwards movement) so a momentary hiccough is less likely to cause a stall. I'm trying to do this kind of manouver with the clutch fully out and controlling the speed with the throttle for obvious reasons. A few more revs probably won't hurt!

On the plus side, I've just seen more pictures from the trial and two of the other enfields landed up on their sides in the same ford so I maybe wasn't doing as badly as I thought!

[Wheaters]

Which trial was it? Well done on having a go.

My attempt at the MCC Edinburgh Trial was a disaster. The bike attracted a lot of interest among other competitors and one rider asked me what my bike weighed. He told me his new Beta weighed only about 60% of what mine does! The big advantage there is that a lighter bike is far better on hills; less likely to suffer wheel spin.

Not forgetting he was probably a far better off-road rider anyway!