Honda 100 125 Information Thread cb cl xl sl


Weird Indy Kid
Building up a 100 there really are not that many places in which to find good information all together. The goal of this thread is to try to put as much information about the 100 and 125 in one place as possible. I will try to keep up with anything that is added in the thread and add it to the first node here.

Location for the shop manual:

Large Build Threads:

CB CL 100
Bore and stroke 50.5mm x 49.5mm
Compression 9.5:1
Displacement 99cc
Horse Power 11.34hp
Piston Pin Size 14mm
Piston not interchangeable with 125 without changing connecting rod
Earlier 1 piece cb125 heads use the same valves
A later 2 piece cb125 head or a XR200 head will provide larger valves while still being able to bolt on

6v (interchangeable with 125)
Information on 12v Conversion


CB CD SL 125
Bore and stroke 56mm x 49.5mm
Compression 9.5:1
Displacement 122cc
Horse Power 11.84hp
Piston Pin Size 15mm
For earlier 125 heads (one piece) valves are interchangeable with the 100
For earlier 125 heads, upgrading to a later 125 two piece head will provide larger valves
A XR200 head will provide larger valves while still being able to bolt on

6v (Interchangeable with 100)
Information on 12v Conversion

6v to 12v swap information

There has been some debate on this. The reasons to go forward with a conversion are to be able to run 12v lights which are brighter and easier to find as well as to lower the possibility of short on a 6v since you can run 2x the watts through with 12v as you can with the 6v which helps bring the resistance down from older parts and contacts.

Required parts
CB350 stator
12v battery
12v lights

Proper Conversion
Here is a doc that was put together that goes over indepth on the process

CB350 stator (plugs do not match so you will have to wire it in yourself, as well as build a new seal because the 350 is a different size. This can be done by cutting and swapping the seal or just making one with some RV Silicone)
12v regulator/rectifier (search e-bay for cm-400,, run a CB350 regulator and rectifier (
12v battery
12v lights
2 1ohm resisters (271-131 radioshack) These need to be added in tandem before the coils primary
Very interesting, as I went and looked at a 1970 cb100 this past weekend. Rusty,crusty,no side covers,nor a title, original tires,dented tank,some rust in the tank a true barn find all for the laughable price of yep you guessed it 350 bucks. I had to walk away,although the hunt is still on, I may call him back and offer a hundy to take it off his hands. WIFEY needs a bike to learn on and if she likes it I'd give her my cl350 and keep the cb 100 for me. It would be nice to have 2 cafes in the garage
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