SOHC.co.uk Forums > CB350/400

DOH! Ignition point system memory failure

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McCabe-Thiele (Ted):
I have no experience with the DS system, my 400 has the Dynatec full system (including coils) that is known to be power hungry.
I have an unbranded E-sytem that Bryan supplied me with for the 500 but to date I am using the points system until it's run in.
The DS system has some circuitry on the mounting plate looking at the listing whereas both my systems have neither - just what look like points type mounted sensors both being adjustable?
The visual difference between the Dynatec & the unbranded E unit is the Dynatec has much thicker wiring.

Mikep328:
On my "bed-in the front brake" run today I did a number of WOT/red line pulls and the bike pulls harder with the OEM ignition than it did with the E-ignition.  There is a noticeably stronger surge going through 6000-6500 RPM than previously - it was quite noticeable.

I have no idea why this should happen.  Timing is the same as it was with the E-ignition.  I thought that maybe the points allow more current to the coils than the E did.  But there has never been any indication that the spark was lacking at high load.

Re timing...I said it's the same but that may not be exactly correct.  The timing with E ignition was spot-on with a strobe both at idle and at full advance (around 2500 RPM).  When I installed the points I set the timing statically - no strobe - so I didn't verify the max advance.  Also, the advance mechanisms were from different original (to Honda) suppliers.  Of course the characteristics should be the same but since I didn't strobe the points, I can't be sure that the max advance is identical for both. 

In any case, it's running great on the points!!

McCabe-Thiele (Ted):
I agree the most likely cause is the advancer curve being closer to original.

Have you eliminated the Placebo effect Mike - its a proven effect on humans. ;D ;D ;D

Mikep328:
"Have you eliminated the Placebo effect Mike - its a proven effect on humans. ;D ;D ;D
"

Good point!  I know that the "Butt Dyno" is notoriously inaccurate and it's possible but the tach really did seem to move much quicker thought the 6000-7000 range.

K2-K6:
Without knowing the spec of E system triggering characteristic it may potentially be hiding something of influence.

Specifically,  the dwell characteristic may be different.  The points using 5 k ohm coil resistance and fairly long dwell to accommodate high rpm drop off (same angular movements, but as rpm increaese then dwell drops away in time that the coil "sees" ) so you get good saturation at lower range with longer dwell tbat may influence the outcome.

The E systems often make use of constant dwell, irrespective of engine speed. This may often be paired with lower coil resistance as it's not needed to mitigate for changes in this dwell time.

The E may possibly need a 3 k ohm coil set to fully utilise and saturate them through from low to mid rpm range. Could account for change in starting too.

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