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The little stunter that could - CBR125

21576 Views 28 Replies 18 Participants Last post by  thebeefsalad
I know 99.7% of this forum isn't interested in stunting but I thought I'd share my little project.

It started off with a near-mint condition 2008 CBR125 that I bought for cheap, as a write-off due to flood damage.
I originally wanted it just for the fairings to swap it over to my current CBR125 which had serious L-plater fairing damage!
I thought the engine would require a rebuild and was going to scrap it anyway..

So when the bike arrived from QLD, I changed the spark plug and it fired up first go! Woo free bike!

So here we see my bike at the time (before fairing damage):

And here we see my bike, covered in stickers to hold the broken fairing bits together, and the donor blue CBR125:

So I swapped the fairings over, and sold my (now blue) CBR125... now what to do with a perfectly running CBR125, shitty fairings, and a frame that cannot be registered?

I knew I'd have a hard time finding sprockets for this thing. So first thing, I had to get the gearing sorted out. Stunt bikes typically run extremely high gearing (+10 to +20 rear sprocket) as most stunts are performed at slow speeds.
I found a local bike shop that made a custom +10 aluminium sprocket. Was around the $100 mark (I provided drawings) so wasn't too bad. In hindsight I should have gone something spastic like +20, but this does the trick.

And compared to stock:

For the front I think I ended up getting a JT -1 sprocket.

Initially I slapped on a fugly streetfighter headlight and made a 'stunt cage' which took 5 minutes and $2 of my time & wallet. The result looked as follows:

Ugly and useless. The 'crash cage' (term used very loosely) lasted exactly 1 stack. Back to the drawing board...

I began searching the net for some 'bolt on' stunt components..as I anticipated, no luck.
So I thought, fuck it I'll build my own shit. I had all the tools already, gas welder etc.. so I began.

To properly stuntify this little POS I needed a solid subframe with solid pegs (to stand on when doing wheelies) and 12 bar (for scraping etc). This forms the basis of the crash cage, IMO necessary for any stunt bike that's ready to cop serious abuse.

So I made one out of 5mm THK MS plate, and used SCH40 pipe for the pegs, wrapped with skateboard grip tape (adhesive sandpaper) for grip, works a treat!
Also made a front cage to protect the rearsets from damage. This was made out of scrap tube lying around. Wasn't very successful in protecting the rearsets unfortunately.

Another stunt specific bit I had to add was straight handlebars. Easier to control the bike and can survive serious impact. I would have gone clipons, but no one makes them in such a small diameter to suit the OEM forks (apart from custom). Renthal bar + Ebay risers = cheap and effective!
Only problem I had was re-routing the throttle cable due to throttle now being abit further away. Also clutch cable was too short so I used a CBR600F4i clutch cable and made an adapter to suit.

Also I've installed a idle adjustment screw. This is so I can set the idle high (4k rpm+) for slow speed wheelies. I used an idle adjustment screw off a CBR600F4 (looks similar to CBR250 idle adjusters, but with different thread) and added a spacer to the CBR125 throttle body to accommodate the offset.

And of course, the most important component which makes a stunt bike a STUNT bike, HANDBRAKE! For those that don't know, this is to do wheelies when your legs aren't covering the foot peg (eg highchair wheelies).
I used a Brembo hydraulic clutch master cylinder, got a spare OEM rear brake assembly, and welded up a new rear brake bracket. Had to get a custom braided line to suit.
Only downfall with this design is that I have to remove the caliper when bleeding the line as the bleed nipple is no longer the highest part of the caliper. To resolve this I could have bought a different caliper (eg off an R1 which has a bleed nipple at the right position) but that option would have cost $$.

So anyway, the final product looks like this:

And at the testing ground:

As seen in the pics, I dented the fuel tank so i can fit my ass on it (it's a skinny fuken fuel tank!) to do high chair / spreader wheelies. I used some grippy material found at Kmart and stuck it on the fuel tank to help when sitting and when doing stoppies/endos.

After some time, the front crash cage was scrapped as it was just a horribly designed POS. I decided to make something abit more 'industrial':

Off to the testing ground:

Now this cage protected the rearsets, but because the CBR125 hasn't got anywhere solid to mount this behemoth of a crash cage, the bracketing shat itself after afew stacks.
So back to the drawing board....

At the moment I'm running to front cage, as I'm stacking less these days (and the subframe does most of the protection). I might have another crack in crash cage v3, but for now I'm just happy to get out there and practice.

I haven't got any vids of me doint epic stacks (I know you all want that..) so I will attempt to capture some and upload in the not-too-distant future.

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21 - 29 of 29 Posts
Cool thread man...........Some good shots taken.....
The little beast is still alive, kicking and going harder than ever! Can't believe how bullet proof these little bikes are (with the right stunt gear on them ofcourse). Still love jumping on it even though I've got the R6 stunter now. Would suggest for anyone who's keen on the sport to invest into one of these!
Do you have the engineering drawings for the rear sprocket please?? As I'm wanting to get into stunting and I have a cbr 125 and this looks like a good way to get started! Also just wondering the size of the chain how many links are in it with the -1 front sprocket so I can't get this main part out of the way please??


hey man i did have eng dwg but threw it out. all you need to tell the machine shop is the pitch, how many teeth, and sprocket ID. Jump on JT Sprockets website and use their drawings as a template.

If you just went -1 front you can stay stock sprocket size but if you're going +10 rear like I did you will need to add links, not sure how many but there are calculators on the net that tell you that just do a search.

bump to an old but ledgendary thread.nappa you have truely inspired me and my little cbr also.it started life as my mrs fist bike now its sitting vertical in my garage and has been a laugh and a half what this little gutless pos can do and for cheap.dirt bike handle bars,12 oclock bar stumt pegs motor cross tyres port and polish ,pod filter ,hollw zorst,blah blah blah.what i want to know is did you disabable the bank sensor/tilt sensor.im about to bring it out again for the summer and have just(last night)put the 12oclock bar on.lso did you have any oil starvation problems or use a wet plug set up.cheers for your inspirations(my mrs isnt your biggest fan tho after what you ve made her beloved bike become.hehe)
oh yeah amd the 60 tooth renthal sprocket helped 2
you can get them on ebay any size u want pricey but there that big u can put a small pizza on the so has multiple uses
21 - 29 of 29 Posts
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