coil for onan

ok so my onan is a B48 and has a points setup i need to know if both cylinders fire at the same time

I would assume so seeing as both wires share a coil and dont use a distributor.

Yes they do.

The both will fire at the same time. being a 4 stroke they will try to spark every time the points close, so it will fire on "non compression" strokes too. Both cylinders "wont go boom" at the same time, if that what the question was aimed at, due to being at different points in the 4 cycle rotation.
If you are questioning if both sides are getting spark, use an inline spark checker. I have seen twins run on one side due to a bad spark plug and sound fine but have no power under load. If you have an IR temp gun, you can check exhaust and/or head temps to see which one isnt firing

I have also seen the onan twins break a rod without cracking the block. It will be running on one cylinder and some times seem to quit for no reason when the busted rod gets hung up. The motor will turn backwards and get freed up and run until the next time it gets jammed.

It takes special (expensive) tools to get into the onan engines and parts are 3x higher than the briggs.

Thanks that's all I needed to know because I bought the wrong Harley coil I bought the one with three prongs instead of two it is for crank trigger ignition so I figured I could hook up the power wire to the coil where it goes and the take the points wire and hook it where the crank trigger ignition wires would go and I think both
Cylinders would fire tell me if I'm right or wrong any help is appreciated thanks

Not sure how the 3 wire harley coils work, but on the old P/C set up, it grounds the primary side of the coil to apply 12 (or 6 with a ballast resistor). I think the triggers are just a high speed mag switch and require the igniter module to work right. You could damage the coil testing with the points and they may not take it back on a return if it doesnt work. I would try +12 in and if there is one marked "-", I would run that to the points. Not sure what to do next with the extra terminal if that doesnt work. It may need to be jumpered to the - or the + and you may only have 1 shot to get it right. Make sure you have an inline fuse on the 12v supply (5A or under)

heres a pic of the ciol its a single fire coil but that is because there is always 2 crank trigger ignitions on a twin cylinder but i plan on putting my ignition power to the + and hook my points to the 2 - post which in theory i thank would send a ground to both of the - post which would make both cylinders fire i may be wrong

That should work

Give an update if that works. I have a K582 that may need a coil and those bastards are $100

I don't know if it works I tried it but had fuel issues and thought it was spark so I used another coil but I might try it again and I will give an update

The coil in my onan went out and I did some research and changed over to a GM HEI coil with a resistor.  Worked great for me.



Now my image is sideways..

^^Was that set up cheaper than an Onan coil?

GM DR39 coil, can be found online for as cheap as $10.  I got mine at a reputable auto store for $25.
I think I used an RU11 ballast resistor.  I think I got it for about $5.

Ignore the condenser that I scribbled out.  This is how I wired it up. My condenser that was original with the points was good.