Forum

[ChrisD]

Gentlemen – thanks for the input.

Tim NZ – I’ve put everything back the way it was (except for the tested new condensor) in the hope that it would give me a starting point for the discovery of the issues. The bike starts and runs albeit coughing a bit. So the work begins. I wish there were an expert closer than my keyboard as no-one in Southern Africa is interested in the old CI models.

BW – Yes, your Bullets are a source of inspiration to me – hence much of the work I have done. BTW I didn’t misquote -see attached image from message 448 on this message board. But maybe you’ve re-analysed and had different results. Anyway, the twin plugs were intended for cooling not power.



Vince – you may well be on track with the regulator as I've discovered acid burns on my jeans near the battery overflow suggesting acid has escaped, perhaps from overcharging. I shall investigate the regulator (its an OEM one) and maybe go for a powerbox.

Adrian – yes, the B50 has much the same advance as the Bullet BUT the curve suggests (I got the image off the Pazon website but I suspect it wasn’t theirs) it doesn’t advance the way an OEM Bullet does – hence the need to slow down and control the rate of advance and therefore the interest in electronic ignition. I’ve approximately located the Indian Bullet OEM and my modified advance curves to the image – see attached.



Cheers all and thanks for the continuing advice. ChrisD

[Bullet Whisperer]

Chris, I have just read that and see I said we lost 3bhp from 32 on our 350 - due to a FAULTY COIL - this would cause misfiring on the other plug, which would cause the loss of power, nothing to do with one plug. Our 350 currently produces 33 bhp using one plug!

[Bullet Whisperer]

Just to add, a lot of what I believed back then, from heeding others and 'self appointed experts' has turned out to not always be the case ...

[papasmurf]

X the unknown quantity plus spurt a drip under pressure.

[Presto]

A question. ChrisD says twin plugs were intended for cooling not power. I understood they were to improve combustion. But my question: cooling is aided by a spark plug, mostly by transference through the plug body/washer to the cylinder head and less from the plug into the air by radiation and convection but how can introducing an additional heat source – the heat generated by a second active spark plug – increase engine cooling? Would not engine cooling be improved only if the second plug was fitted but left unconnected, simply to absorb and transfer heat from combustion without itself contributing to the heat generated? And would that anyway increase engine cooling by any significant amount?

[Presto]

A bit more. The knowing consensus would be that twin spark plugs are an admission of failure in combustion chamber design and are rarely, if ever, used in well-designed engines. They have two recognized functions, a] improved combustion, from two opposed simultaneous flame fronts, and b] reliability from a back-up were one plug to fail. This was a common feature some years ago on long-distance competition two-strokes. A spare plug was located in the head so that if the active plug failed the HT lead could be quickly transferred to the ‘spare’ plug.

[Bullet Whisperer]

Presto, as I understand it, on the systems we used on the 350 [and still have on the 500 for now], if one plug packs in for whatever reason, the other goes down with it - hence when I tested the 500 on one plug, I had a spare plug outside of the engine with the second plug cap connected and the plug earthed. I am no electronic twin spark expert, but Rex Caunt advised me that's how it is. As for heat, the race bikes probably get much hotter than any road going RE's, but I have never had to consider trying to cool them down, even to the point of removing an oil cooler from the 500 after my Brother originally fitted it. Regards, Paul.

[Presto]

I think the old problem that the two plug head on a two-stroke was meant to address was not the failure of the ignition system as such but the risk of a plug 'whiskering' or fouling. Switching the plug lead to the alternative plug would allow a faster remedy than removing the defunct [and hot] plug and fitting a new one.

[Tim NZ]

The potential advantage of Twin Plug the 500 Bullet is not necessarily that of additional (incidental) power gain, but from improved flame propagation rates (combustion) along with the reduction in detonation potential, reduced cylinder head temps, improved fuel economy and ease of starting.


And the ability to safely perform with the same or less ignition advance range for any given compression ratio and octane of Fuel.


Compression ratio is the limiting factor, (keep it under 8.5) as the std RE barrel studs/washers are the Achilles heel.