QuestionI previously asked about a non running 1985 vt1100 shadow. Im getting spark but VERRRRRY weak. I have a brand new battery in it, to begin with. turns over just fine. I checked the ohms on the coils (primary) and getting about 2.6 on that. (i'm not much with electric so bare with me)...just to verify ground to my coils I did jump a cable from the neg. on the battery to the coils just to rule a bad ground out.... My next guess is the CDI box. am I heading in the right direction? I don't want to drop $200-300 on a part I may not need.
AnswerJason, if you have spark to the plugs, it is probably good enough to run. CDI ignitions produce a very quick, thin spark, not like the big blue spark you are used to seeing on a points/condenser ignition system.
Jumping 12 volts to the coil is a VERY BAD idea, if you had the terminals connected to the coil and back to the CDI module. The module is what determines what/when the coils are to fire and if you start poking into the system with grounds or 12v where it doesn't belong then you can be pretty sure that you will be buying a CDI module/box. If both coils ohm out the same, then they probably are okay. Do check the spark plug caps to see if any have opened up. The caps should have about 5k ohms through the cap and wire. Again, all of them should measure about the same.
I answered a nearly identical question here previously... so here is the reply.
If you know that all 4 plugs are dead at the same time, then there is a commonality to check into. Things that affect the whole ignition system in that way would be:
Ignition switch: With CDI ignitions, the ignition switch grounds the sparks out in OFF position, rather than opening a circuit.
KILL Switch: on the handlebars, could be getting corrosion buildup inside or contacts wearing out from age/vibration. Remove, disassemble, inspect and reassemble, then check all wiring to and from the handlebar switch.
Sidestand switch: Will kill spark under certain conditions. Make sure it is clean and tight and working properly.
CDI module control unit: $400 for a new one. You would need a shop manual and appropriate testing equipment to troubleshoot this one. Check wiring connector carefully.
Pulse generator unit: Next to the flywheel, generates timing signals to the rest of the ignition system. A bad connector/connection there could be a cause. Should read about 2ohms.
Camshaft pulse generator: 570-690 ohms 85-86 only.
Go to: www.bikebandit.com for illustrations of the parts, unless your book is an OEM copy with pertinent info already handy.
http://www.hondashadow.net/
http://www.shadowriders.org/
http://www.hsocuk.com/
maybe helpful resources, too
http://www.carlsalter.com/download.asp?fileid=7da1a494948f8f87636662668f82a7a798. for free shop manual file. Haynes, not OEM Honda, though.
Section 5 has step-by-step info for troubleshooting the ignition system.
Bill Silver
PS... be sure you have fresh gasoline in the fuel system. IF the bike has been sitting a long time, drain the fuel bowls. Gasoline will separate and turn into a layered alcohol/gasoline mix in the bowls. In extreme cases, the alcohol will start growing micro-organisms and that will really plug up the jets! No fuel, no start...
