Cb 125T Cafe Racer on a budget

Hello, first of all let me introduce myself, i'm an 21year old student from Belgium, since i'm 15yo i've been busy with engines.
I've got 2 vespa pk 50's ('86 and '92) of which i already fully restored one, last year i bought myself a Hercules KW 125 from '73 (actually 2, 1 decent and 1 for parts) so I already have some mechanical knowlege.

I was searching for a new project which wasn't too expensive (in case i f*cked up) but was still a good solid base. when i stumbled across a cb 125T from '83.
The bike was almost complete, wasn't running but the seller told me when he put it away it was still running so i tought new oil, gas, spark plugs and air filters and i would have a runner. which wasn't exactly the case...

The bike as I bought it:




First of all some small cleaning and thinking about what i wanted to do with it:



removed the airbox, rear fender and other weight and skateboard seatpan:


turned handlebars around and this was the look i'm sort of going for:


removed original seat brackets:


So after this it was official, the bike will never be in it's original state. but the bike even didn't ran. no spark, no gas no nothing. After a lot of swearing and depressing nights the bike fired up sometimes, sometimes not. sometimes at 1cylinder, sometimes 2, sometimes 6000rpm, sometimes 2000... after months of going through every possible problem the bike now runs decent. 1400-1600 rpm stationary, still a little rich but setting 2 carbs by feeling isn't that easy.

now the work is put to a hold for the exams.

Things to do:
-make battery box and welt to frame
-weld bracket for steeringdamper
-mount taillight
-fit slightly longer shocks for more clearence
-make mounting bracket for numberplate
-keep asking my girlfriends mother to make the upholstery for my seat untill she finally starts on it

then testdrive it and change the bike through the next years and have fun.

already have been done:
-open air filters
-carbs jetted
-headlight brackets:


how the bike stands now:

Re: cb 125T cafe/brat racer budget build

btw, the bike wasn't possible to put to original state within reasonable budget (poorly welded exhaust, damaged body parts, rotten seat,...).

comments on the bike are welcome!

Re: cb 125T cafe/brat racer budget build

I likey

Re: cb 125T cafe/brat racer budget build

Shot some more pics to give you an idea of the bike:

headlight clamps:


drilled out sprocket cover:


Good weather driving with open air filters:



Bad weather driving outfit:


Ghetto fix duck-tape battery holder (for the testdriving) ;D

Re: cb 125T cafe/brat racer budget build

Cool little bike! Hard to find, if at all, in the US. Smallest Honda twin I've seen is cb160 (even this is kinda hard to find recently). At one time, I had about 4 or 5 cb160s in the garage! Little Honda Twins are my favorite by far.

Re: cb 125T cafe/brat racer budget build

thanks, these 125 twins are indeed quite hard to find, but they are known for being 'unreliable' and are worth around €1500 in good condition. But i must say it runs great and has more power than my 125 hercules two stroke which has the same weight so i'm pretty stoked to get this one finished (drivable) for the summer.

The bike has around 30 000 km and did a compression test which gave 11bar on the left and about 12 on the right. so the engine is still good, it's just a shame the previous owner(s) didn't care too much for it though.

Re: cb 125T cafe/brat racer budget build

I've got a small problem, the bike runs fine but when the engine gets warm he wants to die after some revving. the mixture settings aren't optimal yet but on the right side it seems like the engine blows ait back into the carburettor. you can hear a clear 'pssst' noise everytime you turn the engine over. can it be that it's just the valves which needs to be set?

Re: cb 125T cafe/brat racer budget build

ok, i'm back and i found out the intake valve on the right side won't close well (blew air in the sparkplug hole and it came out the caburettor when the valve was closed), so the engine head will come off soon. besides of that this build ain't so budget anymore. received my rearset and 2 new exhausts are on their way. so i'm going to order some new to end gaskets and get the bike on the road asap.

also welded the mount for the steeringdamper


rear set:

rearset is for a cb 350 but it fits at first sight, only the pushrod for the shifter is a bit too long but i'll just swap it with an M6 bar

also messing around with the wiring to get everything tucked away

Re: cb 125T cafe/brat racer budget build

So, little update from the last few weeks:

First of all i modified the brackets for the passenger footpegs to mount the rearset on, and designed a system with a cable to connect the brake to the brakelight switch.




After i knew everything fitted it was time to drop the engine out, take the cylinderhead to the local honda shop to get the valves closing properly, new valveseals and to clean the exhaust ports.




When the engine was out it was time to strip the frame and repaint it.




The seat was missing something so go to work with some junk metal and created this



I like it rusty


Cylinderhead is coming back tomorrow so i'll try to get the engine back in as soon as possible and let's hope she'll be good to me and start up without any more problems.

Re: cb 125T cafe/brat racer budget build

Looking pretty nice

Re: cb 125T cafe/brat racer budget build

worked my ass off, got the engine back together yesterday, after some carb problems the bike runs. only have to take her to the shop to get the carbs syncronized. need to solder some wiring at the back, make a bracket for the licence plate and need to shorten my kickstart because it interferes with my rearset. anyone knows if the kickstart is weldable?

Re: cb 125T cafe/brat racer budget build

This bike has oficially a rotten soul. got it the carbs and ignition tuned at a local honda shop. came home, bike ran fine for about 2 min, dies at idle. start again, dies at idle. fired it up when the bike was cold again, dies at idle. there's also a lack in performance now and then. it's safe to say this bike is posessed by the devil itself and i'm seriously thinking about burning it down to ashes right now.

going to bed now, hope i have more patience tomorrow. for safety reasons i'm removing all hamers and wrenches bigger than 14 from the garage so nothing and nobody can get hurt.

Re: cb 125T cafe/brat racer budget build

I made some video's about how the bike's running. it's won't idle properly and the bike won't get over 8000. anyone an idea what can cause this? sometimes the bike idles at 3000 and than suddenly drops to 1500 and dies a few sec later.

http://www.youtube.com/watch?v=LwD8SBz5Z0A

http://www.youtube.com/watch?v=Y0HuPLogI38

Re: cb 125T cafe/brat racer budget build

IT'S ALIVE!!!!!

throttle needle was 1 slip too high so no wonder it was running ridiculously rich...

just needs a bit more tweeking but for now...

time for a beer!

Re: cb 125T cafe/brat racer budget build

Id check the inside of the air filter mouth most of them depending on if its a genuine K&N have a restricted throat making them perform like dirt!
Its a real performance decrease for the bike as it wont run anywhere near to what it should do!

Tom.

Re: cb 125T cafe/brat racer budget build

there are no restrictions in the air filter, it's almost the same as if there were no filters on there. even an elephant could breathe through them...

Original jet size was 85,

I put in 95 because of the open air filters but was a bit too much,

put in 88 to test and it ran like sh*t so... put the 95 back in for now.

The bike is going to a father&son shop which are specialized in japanese (racing) bikes so if they can't get it jetted properly...

Re: cb 125T cafe/brat racer budget build

Got her back from the local specialist, and she is running great. just rode her home and it's just unbelievable how good she runs!

The only thing left to do is change the left ignition breaker because she misfires when she goes over 10000 rpm.

Now it's time to ride her and when winter arrives she will get a small makeover... Because the little bitch needs a cafe seat!

Re: cb 125T cafe/brat racer budget build

So a bit of progress:

plasti dipped front forks and tail



blinkers in the front


cafe seat cardboard mock up


I will start on the mold for the seat as soon as i've got some time this week. I'll be making it from isolation board my grandpa got laying around. Can't wait to see my parents pissed if they find the garage dusty as fuck again...

Re: cb 125T cafe/brat racer budget build

update on the seat: finished the mold today

Re: cb 125T cafe/brat racer budget build

cool bike! I missed out on one of these