Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: peterengland on June 04, 2021, 01:59:57 PM
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Took bike out (550) and it was misfiring so came back after 1/2 mile and checked the headers and #3 was only just warm where all the others were hot. After checking plugs leads and caps I looked at the points and the set for 2&3 were way too wide, reset them at 15 thou and it ran sweet as a nut, I suppose my question is why wasn't #2 misfiring as well?
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Unlike a car type coil these firing two plugs from each end of a single unit have the two plugs operating at opposing polarity. The cylinder conditions may favour one over the other and give this difference between the two at marginal conditions.
The wider gap gives reduced dwell time (amount of crank rotation period the coil is charged for to store energy ready to spark) even a slightly closer gap on one plug would propagate the final spark more easily compared to its pair on the other cylinder.
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You need tocheck static timing as closing gap will retard it
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Have done that, was slightly out but not by much