Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: philward on August 16, 2021, 10:25:54 PM
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Just fitted Hondaman electronic ignition and during the initial points/timing setup prior to connecting the system, left the ignition on by mistake while I went in for lunch. After fitting and the initial ride, all was well - big improvement at tickover and low down power. However, on the ride back home, I noticed that the bike was missing very slightly at tickover. When home, issolated the miss to number 1 cylinder (could feel the 'miss' when putting hand over silencer). Reverted to standard points system, no change. Put electronic ignition back on and changed plug, suppressor cap and checked all coil LT wires around the coils but still no change.
Remembering leaving the ignition on and having had bad experience with aftermarket coils previously (coils on the bike are aftermarket), although a duff coil should affect 1 and 4 cylinders, wondered if the coil could go down internally on one of the HT circuits as a result of leaving the ignition on for half an hour or so. Changed coils to spare set of standard coils (that I reconned using Ash's coil fix method) tonight and miss appears to be solved. (when running in the garage tonight anyway).
Question for the electrickery experts (for my peace of mind) - can a coil go down on one HT circuit internally as a result of leaving ignition on?
Thanks in advance
Phil
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Not likely as the ht circuit to both plugs is one circuit not two
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That was my understanding but unsure of internal circuitery in firing HT voltage down both leads.
Maybe the fault will re-occur
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There is no circuitry one plug at each end of the coil wire
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I understand the external HT - but there must be an internal LT input cuicuit that 'fires up' the HT side. Question is whether:-
1) LT wires from the points (either 1 - 4 and 2 - 3 points wires) feed ONE primary/secondary internal windings that has 2 HT leads from them - in which case, if that primary/secondary windings go duff, then BOTH HT leads (for that coil) have a problem
OR
2) if the LT wires from the points (either 1 - 4 and 2 - 3 points wires) feed TWO primary/secondary internal windings that has 1 HT lead from each that fires at the same time (as both are fed by the same LT points wire input) - in which case, if one of those primary/secondary windings go duff, then only one HT lead would have a problem.
Although I know the principles of how a coil works, I'm trying to figure out why fitting another set of coils has cured the problem - its how this kind of coil is internally wired that I'm enquiring about.
If the answer to the question is 1) then maybe it was missing slightly on 1 and 4 cylinders and I didn't notice it on number 4 cylinder
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As an aside, if anybody has got a set of 750 coils that have knackered leads that are surplus that they want to sell cheaply, I will do Ash's coil fix on them so I have a spare set again.
Thanks
Phil
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One lt coil and one ht coil is all thats in therr