CB125CR Build

Ok so I am building a bike for my wife. It is a 78 CB125 rolling chassis with a TL125 engine that I got in a parts lot. There are several items missing but I will address that as the build goes on.
Here is what I started with


Here is the engine, its pretty much like new and except for some surface grime, pretty clean and mint. I polished the covers and drilled out the drive gear cover. I am replacing all the bolts with stainless allen bolts.


I reassembled the front end, added a headlight visor and changed the signals. Originally I put these drag bars on but wasn't totally happy with it, so as you will see in the next photo, I replaced them with clubmans. One thing I am struggling with is the wiring for the handlebar switch assemblies. They were originally theaded through the handlebars, but with the clubmans, the housings will not fit with around the handlebar and wiring.



Last summer I tried my hand at a fiberglass seat pan. It came out ok, but it will need some bondo for sure to smooth it out, but its a start. Here is a pic of the foam base I made followed by the pan on the bike.




I also needed an exhaust. I found a used header on Ebay for about $20.00 and had a set of drag pipes that don't fit anything (long story, got them for another project, tried to bend the heads to fit, didn't work out so they just sat in my shop for a few years). I cut the straight part of the drag pipe off and using an internal steel coupler, welded the pipe and head together. Not bad considering this is the first time I have welded anything. I also welded on a bracket to hold the rear of the exhaust. I plan to heat wrap it up to that bracket to hide the welds and have a nice chrome cannon sticking out the back. I am on the fence with keeping the slash cut on the end or cutting it flat, let me know what you guys think. Also I am looking for a good deal on some non-black wrap, so let me know if anyone has any sources.





I will post more as the progress continues.

nice wifey will be rocking in style man! my girl gave me my "to do list" for her scoot... holly crap! you should see how long this sucker is! you are just opening the door man... i love riding with my girl.... bit nerve racking at times but still cool to share that same passion!

mbs, whats up.
finally found your post, i love these little 125, make good race bikes.
i like what your doing with this bike. the seat looks good, will take a little
to smooth it out, but worth it. i all so like the exh look. have you had it
running with this exh, if not wear some ear pieces, because these bikes are
loud but sounds good. the wrapping will look good, i would leave the last
couple of inches polished out or cromed. any way looking good.
later.

supercafe said:

mbs, whats up.
finally found your post, i love these little 125, make good race bikes.
i like what your doing with this bike. the seat looks good, will take a little
to smooth it out, but worth it. i all so like the exh look. have you had it
running with this exh, if not wear some ear pieces, because these bikes are
loud but sounds good. the wrapping will look good, i would leave the last
couple of inches polished out or cromed. any way looking good.
later.

Click to expand...

Hey thanks for the comments. I plan to wrap the exhaust up to the rear bracket and leave the rest exposed chrome. I have a baffle that I will put in also to reduce the noise. The seat needs a lot of work, but with some sanding and bondo, it should turn out alright. Not bad for a first attempt at a fiberglass seat. Could have been a little smoother though. I have a lot of ideas, it just comes down to time and money.

Love the shape of the seat. That'll look nice when its smoothed out and painted.

mbs.
that sounds good. and i here you on the time and money!!
but you know alittle at a time.
i think that the bike is going to turn out so well that you won't
want to give it to your wife(lol).
any way good work and keep us posted..
later.

This is looking nice. I never been on such a small bike, how fast are these little things? Will they get up to highway speeds?

Well I don't know what it will do in terms of speed. I am estimating it will go at least 65 mph. We will have to see, its more or less a starter bike for my wife, she won't be out to win any records. Thanks for the comments. -MBS

MBS said:

Well I don't know what it will do in terms of speed. I am estimating it will go at least 65 mph. We will have to see, its more or less a starter bike for my wife, she won't be out to win any records. Thanks for the comments. -MBS

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Oh, so it won't be going off any jumps I guess.

Well at least not intentionally! :

whats up guys.
comment on speed. i have a 175 and i had it up to 80 mph
with a good tale wind on a straight, and when the wind turned to frt
it went down to around 55mph.(lol).
yours is a 125 so i figure you could get 65 on a hill or with a really good tale wind
when you find out let me know, very curious on that.
later.

supercafe said:

whats up guys.
comment on speed. i have a 175 and i had it up to 80 mph
with a good tale wind on a straight, and when the wind turned to frt
it went down to around 55mph.(lol).
yours is a 125 so i figure you could get 65 on a hill or with a really good tale wind
when you find out let me know, very curious on that.
later.

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Well, all I can say is, it is what it is. The price was right - Free, and for a first bike its less intimidating for the wifey to learn on. Its a fun build for me and since I am going to the trouble she is committed to learn or I ride alone. Never had any high expectations for speed, but guessed a top end around 65 mph because my Gilera 106cc does about 45 on a good day. I am trying to keep it as light weight as possible. I will be happy if I get her running and worry about speed later. Will keep you posted.

very true! i started my girl on a 250... then late when she wanted more out of it, i opened up the air cleaner, V stack, and opened the exhuast (had to rejet), she wanted more, so i changed the sprockets, huge diff and lost a touch on take off, can not even notice... next is bigger carb, she likes the bike and has a GSXR600 now as well, so she is happy... but there is always changes taht can be made AFTER she is comfortable!

Re: CB125CR Build - Update, more pics

Hey Guys,

I got to spend some time on Valentines Day with the one I love, and my wife too LOL. So heres a bit of the progress I made. Gaskets came in so I was able to put the carb on. Since I upgraded to a larger, later model 78 Keihin carb I had to make mounting studs for the head. The original carb was held on by a rubber manifold and clamp, the new carb has an aluminum manifold and requires studs. I searched high and low and could not find any metric bolts longer than 2.5 inches. So it was one of those get-it-right-the-first-time deals. I had to thread the bolts in tightly and then cut the heads off sparing every thread, and let me tell you, I needed all I could get. In the end, it worked out perfectly. I also installed a new air cleaner. I also installed the new coil and a red flashing plug cap. I had bought a set of the plug caps a while back and never used them, so I thought I would try one on this machine.



I also stripped, cleaned and heat painted the right side crankcase cover and reinstalled it with a new gasket and stainless allen bolts. I like the black cover with the stainless look. I use a copper anti seize on all stainless bolts because once heated , they don't like to come back out. I purchased a new seat on Ebay - it was a steal. Real nice rigid and smooth fiberglass seat pan, very sturdy. I got it primed with seat foam and upholstered for under $80 bucks shipping included. That came in early last week. A perfect fit. I installed the rear signal lights and started to fab the mounting brackets starting with the bump stop support. I plan to weld a support chassis for the seat that will be connected to the bump stop support so that the seat can swivel/tilt up for easy tank removal and electrics access.

MBS.
the bike is looking really good!!!!
what color are you going with it?
i like what you have done with the eng, with this new filter. did you have to rejet????
any way, once running will have to go for a cruise this summer. my friend and i will be up your
way more than a couple of times.
your build is going to turn out great, and would love to see the final turn out.
any way, looks good and keep us posted...
later.

supercafe said:

MBS.
the bike is looking really good!!!!
what color are you going with it?
i like what you have done with the eng, with this new filter. did you have to rejet????
any way, once running will have to go for a cruise this summer. my friend and i will be up your
way more than a couple of times.
your build is going to turn out great, and would love to see the final turn out.
any way, looks good and keep us posted...
later.

Click to expand...

Thanks Supercafe, I like how its turning out so far also. I have not rejetted, I want to get her running first and then fine tune it. At this point it needs to run before I sink anymore cash into it for things like tires and what not. Getting together for a ride this season sounds like a good plan. I expect to rack up some mileage on my cb750 cafe this season. The tank is currently out to be lined since it had some seepage issues. Hopefully that will resolve the problem and I can just ride the damn thing. I hope to have this little cafe done by summer but we will have to see what happens with getting it running.

lookin good.

I've got a cb125s I'm still messing around with, should have it running good by the time it's warm enough to go out and ride a bit.

Here's a pic:



where did you get your clubmans?

maireeka said:

lookin good.

I've got a cb125s I'm still messing around with, should have it running good by the time it's warm enough to go out and ride a bit.

Here's a pic:

where did you get your clubmans?

Click to expand...

Hey thanks for the pic, thats pretty cool. Would you mind taking some close up pics of the engine? I and building my bike out of several different bikes that I got in pieces and parts, and I am putting it all in a CB chassis. Some pics of how yours is set up would help. The clubmans originally belonged to my father-in-law. He had them on his CB160 cafe he built some 30 years ago. The motor was blown and it just sat covered in his garage up until a few years ago when he gave it to me. I reused a lot of parts off that bike and sold the rest on Ebay. Those clubmans are very solid (a lot more solid then the brand new ones I put on my 750cafe), and they are a little smaller than any others I have seen, so they fit perfect on this little 125. -MBS

i'll get you some pics of it close up tomorrow.

I've had mine running and I rode it a few times, but it never quite ran right. I'm workin on some fuel supply issues right now, bought a new petcock. Also replacing points and spark plug. I want this thing reliable!!

I'll try and get 3 or 4 pics of it all around.

Re: CB125CR Build w/ more pics

Well I was able to get the fuel tank stripped. That paint stripper totally sucked. Not like the good ol' days for Zip Strip. Anyway, after 2 hours of elbow grease using a metal scraper/putty knife, steel wool, sand paper, a wire brush and some BG carb intake cleaner (worked better at removing the paint than the stripper) its all cleaned up. I then washed it down with mineral spirits and gave it a coat of clear. I plan to wet sand it a few times and add more coats for a nice shine. I love the way raw metal looks.

Before: (sorry forgot a close up pic)


After:




I will get some shots of it on the bike once the rubber mounts arrive. I plan on putting a wide red stripe down the center and leaving it raw otherwise. The fuel cap cover (see first pic) is red so it should look pretty cool. I am leaving the under side red also. More to come. -MBS