Topic: Help! 76 CB750 supersport 1 and 4 not running right

[76SuperSport]

Im still working on my 76 supersport for riding this year, I have done the plugs (made sure I ordered the reccomended type from this forum) also did the points/condensors and checked the timing according to the service manual.

My problem, I have the bike running now but #1 and #4 are not running right, the pipes barely heat up and I checked the wires with one of those quick-test light tools that flashes when it detects electric current, the pulses to #1 and #4 are very irradic, I am not very familiar with points style ignition systems yet so I am at a dead end currently.

I am wondering if there is anything obvious I should do, I have been looking for a good set of coils incase maybe the coil for #1 and #4 is bad, but I don't want to rule out the points just yet, even though I replaced them with parts from the local bike shop.

The bike also bogs when I roll the throttle on, I am doing the carbs this weekend so I will have to check this after I verify the carbs are in proper working condition. But I am wondering if an ignition problem with #1 and #4 not firing properly could cause this aswell.

So far I am thinking maybe replace the coils and grab a hondaman electronic ignition system off the forum here.
If you guys have had similar problems or don't mind pointing me in the right direction I would be forever grateful.

Thanks,
Justin/76supersport

P.S. one other thing I forgot to add is that the bike currently has 91+ octane in the tank, it's all I had in a gerry can at the time when I was ready to fire it up. Should I put it back to 87 or 89 incase there is some pre-detonation or some other problem?

[76SuperSport]

P.S.S, Im going to work on the bike tomorrow at my fathers shop, I forgot to even check the impedence of the coils
I'll try testing the coils and re-checking the points

Also found a similar thread after searching more just now. Anyone know where to get a good set of coils in Ontario,Canada?

[Alan F.]

The contact between the plug wire ends and spark plug boots will degrade over time, unscrew the plug caps, snip the wires back a half inch and install new spark plug caps, 5K ohms resistance, the plug caps also degrade over time as the innards corrode the resistance rises unpredictably and can cause imbalance in your ignition system. 

The fact that you've got issues with only 1 and 4 does make me think your points are not set quite right though.  If you're set on getting new coils, there are dozens of other bikes that came with coils that are easily retrofit to our bikes, most with easily replaceable wires.

Run a search for checking coils with an ohm meter, I've posted it a few times and I'm not the only one who has, it'll come up in a search.

Good luck!
-A

[Spanner 1]

+1 with Alan...sounds to me like the 1+4 condenser is not in circuit..easily done by sliding its terminal on the wrong side of the fiber washer at the point connection, have a look at that..don't run out and buy anything yet !, the stock coils on these bikes rarely fail and the points/timing once set is as good as any mechanical ignition ever made ( IMO ).......If you want to remove the tank and look at the 3 black/white wire connection by the coils you may find one is loose in the connector possibly....one last thing, the tester you describe seems to be a 'Volt Tick' and is only useful to detect A.C. voltages not any use around 12v D.C...a simple 12V bulb type tester is all you would need around the bike.....