CB100N motor

[traf]

I came across a clean CB100N motor and bought it. I was wondering if this motor can be enlarged; sharing the same stroke as a 125. Otherwise are there any useful mods I can do with this motor? It came without it's carb or induction spacer, traf.

[Jeff B]

You can bore oversize, as long as you use a piston for a 100. The 125 piston uses a bigger wrist pin. Best thing is freshen it up. Not a lot to help it without spending a ton of money. A little porting. Might find a cam. But to make best use of a cam, slightly bigger carb and better flowing exhaust.  The 125 could be punched out much more.  The cases are different between the two.  To put bigger sleeve in, you have to bore out the cases on the 100. A lot of work for little gain.

[traf]

Just looking at various site's, items on eBay.com listed as 13mm, predatormotorsports say 15mm and another 14mm. Unfortunately my motor is in UK and I'm in France, so no way to verify. Would a rod kit be out of the question? 

[Jeff B]

The CB 100N did not come to the US.  But, it appears to be the same as the one from the early 70's.  If it is the same, you will need proper piston to go larger. The US versions have a smaller opening in the cases. The 125 has the larger opening and thus there were big bore kits in the past. I don't know a 125 rod will help unless you plan on going BIG. You might research that model.  E-bay can be VERY misleading as some adds will claim incorrect fitments.  I have a 71 SL 100.  I simply loaded a fresh 125 engine into the frame.  What are you going to slip the engine into?

[traf]

I'll look around in France for twinshock 125 Honda that's registered to start with , need to be insured and registering a special might be a pain. The 100n wasn't imported here either, it was a 125 market. I don't mind a bit of work if necessary. Thanks