My CL77 resurrection project was moving forward nicely to the point where it kicked over and started easily yesterday. Today, not so much. Wouldn't start. I checked for spark and found it to show weak and intermittent at best. I stuck a test light probe into the plug caps,with the key on and found a weak lighting indicating current to the plugs with just the key on. The bike has the Electronic ignition and A Radio Shack rectifier as well. I disconnected each of these and still had current to the plug caps. Headlight, taillight working okay. Battery new and has been on a Tender.
As I was working towards this point I did notice an odd occurrence on two occasions. I would have sprayed starting fluid into the carbs to check for life in the engine as I was working to get it to run and...... twice after the bike did not kick over and was then left alone for a period the next time I turned the key on there was a very brief pop as in a combustion pop. Just turning the key on brought this about. This leads me to believe this current issue was there all along. If so then why the successful running of the engine yesterday and the no start today??? Ant thoughts on this puzzle? Thanks, downtoscratch
Current to spark plug leads when ignition is switched on....
A coil will normally fire a plug when the current is interrupted, ie when it is switched off(collapsing field). The switch contacts could be in poor shape and not making good contact. Try running a wire from the battery to the coil terminal, to bypass the switch, and see if it gets better spark.
'65 YG1
'65 CB160 '66 CL160 '66 CL77 '78 XS650 '79 GL1000 '69 T100R '68 TR6 '69 T120 '72 750 Commando my company car is a Kenworth
Mike, Thanks for your input. I have good voltage to the coils. What switch did you have in mind that I would be bypassing? No contact points as they were replaced by the electronic plate. I disconnected the ignition module and still have weak voltage to the plug caps....... DTS
If you have good voltage at the coil connections(under load) the ignition switch is probably good. Disconnect the ignition module from the coil and short that coil terminal to ground, does that produce a spark? I wouldn't think the high tension lead should put out battery voltage, the primary and secondary circuits should be insulated from each other. Do you have another 12 volt coil laying around to try in its place?
'65 YG1
'65 CB160 '66 CL160 '66 CL77 '78 XS650 '79 GL1000 '69 T100R '68 TR6 '69 T120 '72 750 Commando my company car is a Kenworth
Mike, With the exception of your (under load) directive I followed your advice and swapped out a new coil for one on the bike connected only to the black + wire and grounding to the engine the results were the same ........ Dim lighting of the test light when inserted into the plug socket, about half the intensity of the full 12 volts when touched to the positive pole of the coil. DTS P.S. I do not get any such current flow when duplicating this same test on two other bikes.... P.S.S. perhaps you could tell me how I'd do the above ..... under load. Thanks
Malcolm, As mentioned in my first post here the bike went from running fine to a no go status overnight. Lacking the finer instruments of a real troubleshooter I went with what I had handy. The probing of the plug leads was a simple attempt to verify spark and as a result of this I noticed the weak voltage passing through the spark leads. I still have this condition now but I think my no go matters lie elsewhere....... Fuel supply now has my attention. Thanks to you and Mike in Idaho for your helpful input. DTS
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