Cafe Racer Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
10,522 Posts
Discussion Starter #1
how do you make/adapt a CDI set up to a CB125? where can i get more info on how it all works and what i would need to make the swap?
thanks


There is the right way, the wrong way and the british way to do anything!
 

·
Premium Member
Joined
·
11,267 Posts
Jag,
I only researched CDI night and day for about six months trying to come up with a programmable CDI I could build myself and have it reasonably reliable, resonably priced and able to perform to 13,000 rpm. I gave up.
Discovered my time was much better spent working and just buying a freakin system.
Anyway...for the CB125 you'll want to first check out some Honda two stroke dirt bikes to find one that shares a similar crankshaft taper to the CB125. Then see if it's feasible to run the 2 stroke rotor and stator on the CB (isolated from oil or not). A 2 stroke CDI is going to fire every rotation...no biggie, you'll just have a wasted spark. However you won't have lights since the mag/cdi used on most dirt bikes doesn't have a lighting coil
Unless you are racing the bike you'd be way better off just doing and electronic conversion to the points.
If you are racing...the easiest route will be a PVL system of some sort if you can't find a dirt bike system that will work.
JohnnyB
 

·
Premium Member
Joined
·
11,267 Posts
Jag,
I only researched CDI night and day for about six months trying to come up with a programmable CDI I could build myself and have it reasonably reliable, resonably priced and able to perform to 13,000 rpm. I gave up.
Discovered my time was much better spent working and just buying a freakin system.
Anyway...for the CB125 you'll want to first check out some Honda two stroke dirt bikes to find one that shares a similar crankshaft taper to the CB125. Then see if it's feasible to run the 2 stroke rotor and stator on the CB (isolated from oil or not). A 2 stroke CDI is going to fire every rotation...no biggie, you'll just have a wasted spark. However you won't have lights since the mag/cdi used on most dirt bikes doesn't have a lighting coil
Unless you are racing the bike you'd be way better off just doing and electronic conversion to the points.
If you are racing...the easiest route will be a PVL system of some sort if you can't find a dirt bike system that will work.
JohnnyB
 

·
Registered
Joined
·
10,522 Posts
Discussion Starter #4
not to sound dumb but what is a PVL system?
i plan to race the bike. will be spinning close to 13k RPM.
ive built motors before but this is my first time trying to make motor parts work on a motor they werent ment for
any other good ideas of a reliable ignition for my bike?


There is the right way, the wrong way and the british way to do anything!
 

·
Registered
Joined
·
10,522 Posts
Discussion Starter #5
not to sound dumb but what is a PVL system?
i plan to race the bike. will be spinning close to 13k RPM.
ive built motors before but this is my first time trying to make motor parts work on a motor they werent ment for
any other good ideas of a reliable ignition for my bike?


There is the right way, the wrong way and the british way to do anything!
 

·
Premium Member
Joined
·
11,267 Posts
PVL is a brand name. It's a company that makes a whole slew of different mag/cdi ignitions to fit all kinds of bikes. If a person is lucky they can bolt one right on...if they aren't they have to try to mix and match parts to make it fit.
Here's the unit I adapted to fit my 175.
http://www.jrbranson.com/HondaRacer/CB175/Ignition.htm

A CB125 could run a pretty small battery in a total loss setup for racing (ignition runs off the battery only). There are quite a few electronic "points replacement" systems out there...still would probably have to be adapted to fit the CB. But from a racing standpoint you wouldn't have a big weight penalty since you could run such a small battery and remove the alternator and stator.

Here's where the work comes in. You'll have to do all the research to find the parts unless you can find someone that's already done a similar modifications. Look around for internet groups that specialize in single cylinder hondas.
JohnnyB
 

·
Premium Member
Joined
·
11,267 Posts
PVL is a brand name. It's a company that makes a whole slew of different mag/cdi ignitions to fit all kinds of bikes. If a person is lucky they can bolt one right on...if they aren't they have to try to mix and match parts to make it fit.
Here's the unit I adapted to fit my 175.
http://www.jrbranson.com/HondaRacer/CB175/Ignition.htm

A CB125 could run a pretty small battery in a total loss setup for racing (ignition runs off the battery only). There are quite a few electronic "points replacement" systems out there...still would probably have to be adapted to fit the CB. But from a racing standpoint you wouldn't have a big weight penalty since you could run such a small battery and remove the alternator and stator.

Here's where the work comes in. You'll have to do all the research to find the parts unless you can find someone that's already done a similar modifications. Look around for internet groups that specialize in single cylinder hondas.
JohnnyB
 

·
Registered
Joined
·
10,522 Posts
Discussion Starter #8
Kitaco makes something that i saw used but seem to have a VERY hard time finding someone to take a few minutes and help me set up everything the right way.
dont want to run a total loss set up. would like to take off the batery instead. dont need the revs as much and plus would like to "option" to go street one crazy day.


There is the right way, the wrong way and the british way to do anything!
 

·
Premium Member
Joined
·
11,267 Posts
I've got a Kitaco mag/cdi ignition on our 70cc Honda racer. We use an "inner rotor" type which provides no voltage for lighting. However Kitaco also makes an "outer rotor" type that does. Not sure if they make one for the CB125 but I'm sure they make something close.

Not a lot to explain. You buy one, bolt it all on, start it up. The full kits come with everything you need. The outer coil type replaces the stock alternator setup with a magneto setup. The critical items as far as fit are the rotor (will the taper fit the crank) and the stator plate ( will it fit the crankcase) and will the whole thing fit under the stock alternator cover.

They are extremely simple setups...pretty much just fancy lawn mower or chainsaw ignitions.
JohnnyB
 
1 - 10 of 10 Posts
Top