atc 90, no voltage?

[buffalobill]

hi, i just picked up an old atc 90, and the guy gave it to me letting me know that the wiring was hacked and he couldnt get any spark. he thought the coil might be bad.

i put my multi meter on the yellow and black wires coming out of the case, and spun the motor over to see if i was generating the 12 volts that i need. I am not getting anything. the cover is off the side, i can see the "magneto/stator (i dont know the correct term for this)" spinning, and the two wires are connected to what appear to be opposite ends of some sort of magnetic ring?

how do i fix this, to generate the 12 volts?

[Dirtcrasher]

You may never generate 12 volts just turning it over like that. If you have a service manual (many are free here on the site) you can OHMM out the coil under the engine case to see if it's in spec. Just removing the cover may show you something in there. But, OHMMS are OHMMS; Multimeter it out!

I'll never claim to know crap about the US90, but test values are what they are so begin there. That trike must have points and a condenser........

The coil on the frame rarely goes bad. It takes the 12Volts up to a very high voltage to gap that spark plug at a higher voltage. Aren't some of these 6 Volts systems?

Anyhow, try to get a service book or if you can get a hold of Mike at VMS, or Shortline, they will have the answers you need I'm willing to bet.

You may have to search around the sight a bit, most of the 90's are crap but a few gutys aside from the ones I mentioned above are experts on the old 90. Thats were it all began anyhow!!

[buffalobill]

yeah, right away i figured the coil would be fine, i just searched and am definetly confused about what type of measurements i should be taking off the yellow and black wires coming out of the case. ohms? I have noticed people talking of AC voltage coming out, is that what the "magneto" produces?

[Rjfabwerx]

I'll betcha it's the points...Also check and make sure the little boot thingamajig that snaps onto the spark plug has a good connection...

[buffalobill]

i wish, man, this is the wires coming out of the case before the coil and points, not after! i am just trying to figure out how to get power to the coil, at this point.

[shortline10]

Its a 6 volt system first off if its a points motor LOL .
Each wire comming out of the mag is a hot wire , one is for the lights and the other is for the ignition .
Change the points first .

[buffalobill]

oh ok, this is only a 6 volt system, and both of those wires are +, so all i have to do is ground my meter to the frame, and hook up the + test lead to the black wire while i spin it over?

ok, lets say i do that, and get some voltage, how do i access the coil on these things? do i have to drop the motor out of the frame to get to it?

I am just trying to go through the ignition from beginning to end, so i can be sure that it runs. ps, where do i pick up points for an unknown year atc 90?

does anyone have any way i can find out what year it is with a vin number?

[MonroeMike]

Try entering the VIN here.

http://atcvin.webs.com/

[buffalobill]

ok, i spun it over with the - on the engine case, and right away i got 6 volts. the wiring was hacked up, but enough of the original wiring was there so i just cleaned that up enough for it to get power to the coil. now how many volts should be coming out of the coil? when i am spinning it over backwards with a drill i am getting 5-600 volts out of the wire, and that is as high as my multimeter read. is this sufficient, and should i start going through everything else now, or is that low for this system?

btw, i ran the vin, i found out its a 1976 atc 90, thanks for that site!

[MonroeMike]

Here's a manual, if you have not located it yet.

http://72.52.143.80/~trikes/atc90_73...vicemanual.pdf

[buffalobill]

ok, im getting some spark, not that great, enough to zap me when i hold the plug, but i think i will mess around with the points gap and spark plug gap later. these engines rotate counter clockwise, correct? i just dont want to spend a half an hour trying to spin it the wrong way wondering why it wont fire.

[shortline10]

Yep counter clockwise .

ok, im getting some spark, not that great, enough to zap me when i hold the plug, but i think i will mess around with the points gap and spark plug gap later. these engines rotate counter clockwise, correct? i just dont want to spend a half an hour trying to spin it the wrong way wondering why it wont fire.

[buffalobill]

put a new plug in, and adjusted the plug gap and the points gap. i have been spinning it over with my cordless impact trying to get it to fire, but it won't. i messed with the timing some, and adjusted the points to open just before tdc. still nothing. I did notice some sparking down by the points however. how much timing do these engines need?

[vintagemotorsports]

just a tip, If you are getting a spark arcing over your points you more than likley have a bad condensor , it is bolted to the coil bad news is you need to be a mouse in order to get to it the coil is located between the stamped frame above the rear of the engine , its tricky but you can get to them change that i bet you will be close .

[buffalobill]

ok, so when the spark is arcing intermittently around the points plate i probably have a bad condenser? even if i am getting spark at the plug when grounded on the case?

is there a way to check the condenser?