'73 CB125S Cafe

Hey all! First time really monkeying around with bikes, so I'm pretty interested to see how this goes!

Really looking to play to this little 125's strengths, it'll never be fast, but it sure is pure and simple and light. Looking just to build a little toy to zip around the city in the summer. Something really unique (I've yet to see another proper cafe racer around here!)

Something like this is the look I'm going for:



EDIT: Stock airbox is going back in! New inspiration! Gosh damn, this looks clean:



Got the bike in good running shape for $600 CAD. Everything is in pretty good condition, including the tyres!

Here she is just after I got her home:



As i was pulling everything apart, I took at moment to imagine what this little bike will look like when done:


Tear down went really well for my first experience, no nasty surprises. Here's where it's at now:



While I'm waiting for my seat to show up before I can futz with the frame, It's time to clean up this little engine!



The only thing I'm really intimidated by is the electronics, so expect quite a few questions once I get to that point!

That inspiration build is very sweet! The simple ones are the best
Put your money into rear shocks that actually damp as well as rebound, tyres that stick, a hydraulic front brake, lower the forks up to 1" and Keep the front mudguard as a fork brace!
Click the link below and lose a life time of build info overload!
http://www.dotheton.com/forum/index.php?topic=12552.0

Erskine said:

Click the link below and lose a life time of build info overload!
http://www.dotheton.com/forum/index.php?topic=12552.0

Click to expand...

Thanks! That link is great!

The plan was to get all the major work to get it back on the road as a cafe racer done through this winter, and then move onto nice to haves next winter (brakes, suspension, etc). Any brands/styles of brakes/suspension you'd recommend that fit on a small bike nicely?

Thanks for the tips!

Your tyres look pretty good as it is. I used girling replica shocks marketed as Midas. Avoid the cheap piggy back chinese ones unless you have the ability to re engineer them.
Peops have adapted hydraulic pit bike calipers to replace the cable jobby.
I really do suggest putting your feet up with a good bottle of wine and a roaring fire and learning from the collection threads!

Figures! I already ordered my seat, and I see one that's a bit better fit from one of those links. Luckily hasn't shipped yet, time to weasel out of that sale!

really clean bike! almost a shame to modify...

Really fun and nimble bikes! enjoi!

jungalist said:

really clean bike! almost a shame to modify...

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Yeah, I get what you're saying. Going to try to keep the frame and major components as unaltered as possible. I feel a little bad chopping/modifying a frame from a machine that's older than me!

some of the nicest builds are pretty much kept standard other than reprofiling the stock seat lower with a bum hump at the back, ace bars, a sports exhaust and a k&n air filter. Job done!
The rest of the energy could be spent on the more important stuff like new wheel bearings, swinging arm bushes,optimised braking system, fork rebuild. Needle roller steering head bearings. Spending hours and funds deleting a perfectly good electrical system will only save you as much weight as not eating a full sunday roast dinner before you ride

As Jungalist says, its a pretty bike as is. these bikes are only going to go up in value! But mess with them too much and they become worth jack shit ... IE make sure everything you do is reversable. A If you get the bug to really go for it the CB can be sold to finance something else that you can go radical on. Motorcross bikes are cheap as chips second hand and cafe up well

Yeah don't want to do anything too drastic. Was planning on adding a frame hoop and zinging off some brackets I won't be using, but I think I'll keep the frame as is. I'll have to rig up a battery tray and seat mounts as delicately as I can.

Was cleaning up the engine a bit this evening. Looking pretty good. Not going to paint, love the bare metal look. Just using WD40 and simple green, and it seems to be doing the job. May end up polishing a few covers or maybe painting, I'll have to see.

Anybody have have any better tricks to get this engine cleaned up?

Bit of progress on the little 125!

New parts from DCC!



I hear this Hooligan muffler is pretty crazy loud, sure it will pass safety on a 125...

Love the look of these filters!



Use you imagination, and this is how that tail light should look



Nice clean speedo



Starting to look pretty ok!



All just mocking everything up at this point. Checking fit/look/etc..

Happy with everything so far. Exhaust is up next and then need to sort out everything on the new bars after that!

Don't be surprised if you actually have to lean the fuel mix for that filter rather than richen it.
I had to drop the needle one notch, Defo no main jet change. A lot of other people have had to do this on their cb's and cg's. I know, it defies logic.

DCC sells junk like that Emgo filter.
The 125s HATE changes to intake and exhaust.
Dont be fooled to think that the stock airbox was holding back HP, this is a motor that is making more then 100hp per liter of displacement. The airbox is not the weak link. Also dont be fooled into thinking that a pod will flow more air.

Try and make meaningful and functional improvements to motorcycles

surffly said:

The 125s HATE changes to intake and exhaust.
Dont be fooled to think that the stock airbox was holding back HP, this is a motor that is making more then 100hp per liter of displacement. The airbox is not the weak link. Also dont be fooled into thinking that a pod will flow more air.

Click to expand...

Definitely fooled by seeing just about every other CB125 and 100 running a pod style filter. Didn't figure it would add too much performance, but I didn't expect it would hinder it.

So is it possible to get it running well with a pod filter? Or will I always loose performance not running the stock air box?

Any help is good help. Still new to all of this!

Its easy to get fooled.
Many are just playing dress up, so a bike to take pictures near is just fine.
Others just flat wouldnt know a well running engine if it knocked the coffee out of their hands.

Yes you will have a loss no matter what you do.
Some will claim to get things to run "just fine"....but they are wrong.

Can you tune it to run well enough to ride? Sure I guess, but to me its a large sacrifice for not that much gain.
Before we get onto the topic of jets, this is again an area that people become fooled.
There is ZERO chart that says "with this mod, use this jet"
only way to do it is to buy three or four complete sets of brass and use trial and error. This also assumes that you have mastered tuning the stock bike and know what is right.

If all you want is to copy the same old look then have at it.
But if you are trying to find a little more power in the tiny engine then a pod isnt going to do it.
The bottle neck is the physical head, that is the restriction. So no intake change will do much to improve things, only hurt them.
Also emgo is about the most useless part on the face of the earth. Uni or the like are much better.....but the small single will still hate it.

How much riding, tuning and such have you done with the stock bike?
It is important to spend some time with the bike stock before hacking into it. This lets you build a base line and develop the all important and almost universally over looked "ear" for the bike.
With people that are new to the hobby it is important to figure out right vs wrong, so that when things go bad they know something is up. An old bike will give you plenty of chances to wrench on it.
I am always surprised by how many people I meet out on the road that have an engine running on 3 out of 4 cylinders or something else, but they have no idea because they don't know what right sounds like.

Jesterhead said:

Definitely fooled by seeing just about every other CB125 and 100 running a pod style filter. Didn't figure it would add too much performance, but I didn't expect it would hinder it.

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I have to agree with surffly on the intake mods, the stock design works remarkably well. I did a bit of production class road racing with a 125 back in the day. Even with a Yoshimura cam and port work the stock air box worked best. Even a K&N filter inside the stock air box did not yield performance improvement. I cringe when I see K&N filers on bikes, this article will explain why:
http://www.nicoclub.com/archives/kn-vs-oem-filter.html
-Bill

spurlock said:

I have to agree with surffly on the intake mods, the stock design works remarkably well. I did a bit of production class road racing with a 125 back in the day. Even with a Yoshimura cam and port work the stock air box worked best. Even a K&N filter inside the stock air box did not yield performance improvement. I cringe when I see K&N filers on bikes, this article will explain why:
http://www.nicoclub.com/archives/kn-vs-oem-filter.html
-Bill

Click to expand...

I love me some charts!

I'll give that a full read when I have the time!

Thanks, I really do appreciate the advice!

yup look through a k&n filter at the light, the holes are huge my nose filters better
the biggest fail is when you see a set of pods or k&n and no rear fender , the street is very dirty and it is fine dust constantly picked up and flung by the tars

You know what?

I was a little bummed to hear about the performance hit of pod style filter because I love the look so much at first. But now I'm totally stoked to get back out and bolt the stock airbox back on! Luckily my side covers are in good shape.

Thanks for filling me in with the facts, guys!

BONUS when somebody asks you why you don't run a pod and the "open triangle" look, you can retort
"because i am not an ignorant poser"