Hitchcocks Forum

Morning Chaps



Slo Poke (fitted a BTH Magneto) started second kick, yesterday morning, but wouldn't respond to the throttle - well, unless you count erratic running, frequent huge bangs and flames leaping out of the exhaust as 'response'.



Coil resistance (and remember this is the solid state coil that BTH supplies) is 0.5 ohms, which seems wrong, but I can't find a definitive answer on the interweb.


Can anyone tell me, for sure, what it should be? Thanks in advance.

Apologies for the above dogs' dinner of a post. hopefully it makes sense.

OK



I've done some more digging and it seems like 0.5 Ohms, on the primary side, and 2.2k Ohms on the secondary side, would be to spec.



So does anyone have any thoughts on the popping, banging and no power thing? To me, it seemed as if the spark wasn't advancing but - given that the BTH has an electronic advance curve - I ruled that out as unlikely.



Following the popping and banging episode, I changed the spark plug and he wouldn't start. Changed back to the old spark plug and he still wouldn't start.



The last time I rode him (Friday before last) he started third kick and ran perfectly, so I'm a bit at a loss.

Hi C.J. - I can't help with info on the ignition components, but having ridden your machine myself in the wet, I remember a lot of misfiring, suggesting water was getting onto components and / or connections under the front of the tank - perhaps rhere could be a bit of corrosion lurking somewhere, causing a bad connection? Other than that, put your finger in the carb intake and open the throttle, to make sure the needle is still clipped into the slide and not dropped out,which can cause the symptoms you describe. Regards, Paul.

0.5 is correct, if it was ok prior to fitting the mag?, I would be rechecking the timing.

Thanks Paul



The connectors are good but I'll try your suggestion for the needle.



Currently, I'm wondering whether the exhaust rocker is sticking as there was obviously a lot of unburnt fuel making its way into the exhaust pipe - and you may recall that this happened before (although, on that occasion, it bent the pushrod) and that the bore on Slo Poke's rocker oil feed pipe is quite small.



If that's the case - or if that's the best I can come up with - you can expect me asking you to install new rockers and a standard oil feed pipe (in a hurry, as usual).



Obviously, I'm hoping you're right about the needle thing.



I'll let you know.


Iain

Have you re-checked the timing? The symptoms sound like the timing might have slipped, I assume it's still a taper fit to the drive pinion? I'd also try phoning BTH for their advice, premature failure of new devices is not unknown after all, and I have heard of a similar fault on a new BTH fitted to a Velocette. (Reported on the RealClassic message Board.)

REgards, Mark

Hi Revband



The magneto has been on Slo Poke for a couple of years and is about the only thing that hasn't caused me some angst, in that time - so I guess it may be taking its turn.



Hi Mark



Yes, it's still a taper fit - and the possibility that the pinion had slipped was a theory that was discussed, with my pal, yesterday.



TBH, we got into the coil, because we couldn't see or hear a reliable spark, but it was very sunny, yesterday; getting the magneto spinning fast enough while holding a spark plug to the head has its difficulties on a Slo Poke; and (as it turns out) my mate's multimeter is manufactured, in China, by the 'Pi Lo Sh*t Company' and was reading 30 odd Ohms on the primary side.



Thanks both. I'll report back.

A tip for holding the plug, get 2 smallish crocodile clips and bolt them back to back (they usually have holes in the ends for attaching a wire, a 3BA or similar nut and bolt will clamp them tightly together) and then clip one end round the plug and the other attach to a cylinder head fin. Perfect "no hands" spark checking! I read this recently and after making one wondered why I'd struggled for so many years!

REgards, Mark

Good tip. Thanks Mark.



Doing further research, bringing the kill switch wire into contact with the HT wire, can also send the BTH a bit mental - but, on my machine, this is cut very short (about 2") and insulated as I stop the engine in gear.