andrsn
XS650 Addict
I am rebuilding a couple 1990cb125t that I picked up for super cheap, unfortunately 2 of 3 are missing the CDI boxes and you can't find them for under 150$ each.
So I mapped out my CDI box, and have a few questions. First off, here is a link to the diagram i made for the cb125t ignition system:
This is the CDI box that I would like to try and adapt to work (its from a
cm250):
My 2 main areas of question:
1. How does a CDI advance timing? Is it programmed or does it just speed up as the
alternator spins faster and faster? If it is programmed in I would worry that it
wouldn't work, although most small motorcycles seem to have a pretty standard
advance curve, no?
2. I am assuming that because I have a coil for each cylinder on the 125t, this
ignition system is not a "lost spark" system. Can I convert it to a "lost spark"
system like the cm250 has? Will it hurt an engine to be sparking at the down
stroke of a cylinder if it wasn't designed to. Also, can I just splice the two
125t coils together off the one wire feeding the coils from the cm250 CDI? I only ask because the stock CDI has a wire for each coil, while all other CDI's I seem to find have one wire for one coil that feed 2 spark plugs (I think this indicates a lost spark system).
Any help or advice would rule
So I mapped out my CDI box, and have a few questions. First off, here is a link to the diagram i made for the cb125t ignition system:
This is the CDI box that I would like to try and adapt to work (its from a
cm250):
My 2 main areas of question:
1. How does a CDI advance timing? Is it programmed or does it just speed up as the
alternator spins faster and faster? If it is programmed in I would worry that it
wouldn't work, although most small motorcycles seem to have a pretty standard
advance curve, no?
2. I am assuming that because I have a coil for each cylinder on the 125t, this
ignition system is not a "lost spark" system. Can I convert it to a "lost spark"
system like the cm250 has? Will it hurt an engine to be sparking at the down
stroke of a cylinder if it wasn't designed to. Also, can I just splice the two
125t coils together off the one wire feeding the coils from the cm250 CDI? I only ask because the stock CDI has a wire for each coil, while all other CDI's I seem to find have one wire for one coil that feed 2 spark plugs (I think this indicates a lost spark system).
Any help or advice would rule
