Seeking Info on wiring the coil on a US90/atc 90

[Tramo111]

I just purchased a 1978 atc90 with a early us90 engine. Someone had rigged up the wiring and the coil wire was pulled out of the coil. i purchased a used 6v ac coil and condenser. the coil has 3 wires coming out of it, not counting the plug wire. the wires are 2 grn and 1 blk, 1 grn is mounted and grounded to the coil frame. the blk and other grn go into the coil itself. the condenser is mounted on the rear of the coil with 1 wire coming out of it with a double female plug on it. i have studied the wire diagrams but they are confusing. if some one could help me . i woud appreciate it. Randy in Tennessee. ps the bike has no lights and im not planing on putting any on it. i just want to get it to run and ride.

[gimmeamidget]

The only wires you need to make it run are one green grounded and the black to the coil. The other green runs to the on off switch but will run with it unplugged just won't shut off. As for the condenser, it should be mounted under the cover with your points. I have found with these bikes if they won't run its usually an issue with the points needing to be set or the valves adjusted.you can hook a test light to the black wire and if it's working you should get it to light up with each rotation of the engine.

[gimmeamidget]

If your not getting any spark check the points gap and rub a piece of 400 grit or similar sandpaper between the contacts on the points. Sometimes they get corroded and won't work.

[Tramo111]

The only wires you need to make it run are one green grounded and the black to the coil. The other green runs to the on off switch but will run with it unplugged just won't shut off. As for the condenser, it should be mounted under the cover with your points. I have found with these bikes if they won't run its usually an issue with the points needing to be set or the valves adjusted.you can hook a test light to the black wire and if it's working you should get it to light up with each rotation of the engine.

ok so run the primary from the generator to the blk coil wire. where does the grn wire that is grounded to the coil frame go. what plugs into the condenser double female plug? there is no spot for a condenser near the points.

[Tramo111]

If your not getting any spark check the points gap and rub a piece of 400 grit or similar sandpaper between the contacts on the points. Sometimes they get corroded and won't work.

i havent tried to fire it until i know its connected right .im afraid i will damage it the coils and condensers for the us90 are hard to find and expensive.the bike didnt have a working coil installed.

[gimmeamidget]

The original coil didnt have any green wire. It was grounded by the bolts that mount to frame and just had a black wire. The condenser is bolted inside the frame behind the air box. On your new coil either green can be bolted to frame or both it wont matter they are just ground. You dont need to connect any other wires to anything. As long as the black coming from the generator is hooked to the coil and the coil is grounded and the condenser is hooked up and grounded to frame aldso and points are set it should spark. I dont believe you can hurt these by hooking up wrong. The way you turn bike off is by grounding your primary wire so you will not hurt anything if its not right. Is the factory condenser still on bike? I have had much better luck with oem parts than aftermarket but either should work.

[gimmeamidget]

https://www.google.com/url?sa=i&rct=...00294540256831

[gimmeamidget]

The link should show a wiring diagram to show you what colors hook where. Your coil will work also just hook greens to frame to ground and hook everything else back to stock.

[Tramo111]

the condenser looks original . which wire plugs into the condenser? 1 of the grn coming from the coil is grounded to the coil frame and has a white band around the wire ,the other grn wire coming from the coil comes from inside of coil and both grns have male bullet conectors. thanx tramo

[Tramo111]

OK now i have fire to the points but plug not firing. the meter shows 12v coming from generator when i pull starter rope. meter shows 4 to 5 volts are getting to points.

[gimmeamidget]

What is the point gap when points are open? the points should be closed and only open when the lobe opens points and that should be on F mark and the open sends volts to coil to spark.

[gimmeamidget]

If I recall correctly gap should be around .012 inches with feeler gauge.