CBR250 Forums banner

1 - 20 of 29 Posts

·
Registered
Joined
·
1,327 Posts
Discussion Starter · #1 ·
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.


-Alex
 

·
Registered
Joined
·
11,384 Posts
Nice write up. Not a big hektik stuntz fan, but I can appreciate the work gone into it :D

And videos will be awesome
 

·
Registered
Joined
·
13,735 Posts
How hard is it to get the little 125's front wheel pointing skywards?

Justin.
 

·
Registered
Joined
·
1,327 Posts
Discussion Starter · #7 ·
Justin - comes up without hassle (1st gear clutch wheelie). Also comes up pretty easy in second gear for higher speed wheelies. It's all about body weight transfer!

Worm - I actually stole the idea from Youtube after seeing some Europeans do some insane stunts on this bike. It doesn't have much power (10killerwasps) but that's more than enough for its purpose. And the fact that it's not as responsive as a 600 gives me a 'safety factor' if something goes wrong, eg I stack and jam the throttle open!
 

·
Registered
Joined
·
550 Posts
That's an awesome project! If I wasn't so scared of falling off, I'd be into all this stuff :p

Expressing interest for vids! :D
 

·
Registered
Joined
·
1,327 Posts
Discussion Starter · #9 ·
quick stunt session snaps after work, sorry no stacks!





 

·
Registered
Joined
·
2,945 Posts
nice work. lol the 12 bar is practically a 1 bar as it goes a bit past 12 by the look of it sitting on the bar. :)

cool to see you having a go and modding and learning to ride it yourself. :)
 

·
Registered
Joined
·
4,646 Posts
cool write up mate.

thats a beast of a subframe! 5mm steel, no wonder it pops up so easily now, the CoG is about 10 metres behind you. haha
 

·
Registered
Joined
·
1,327 Posts
Discussion Starter · #15 ·
fortytwo said:
cool write up mate.

thats a beast of a subframe! 5mm steel, no wonder it pops up so easily now, the CoG is about 10 metres behind you. haha
god dayumm my secret's out!

I'll make some vids this weekend pending weather. Also bought this in the meantime:



now i don't need keys for anything!

Also here's the youtube vid that inspired me:

http://www.youtube.com/watch?v=tzoixvwMx1g
 

·
Registered
Joined
·
1,327 Posts
Discussion Starter · #16 ·
Well the fuel cap arrived but didn't fit, shattered! Anyone got ideas how I can butcher the fuel cap to open/close without the need of a key?

Ordered a new pair of rear bads from Metalgear.. Took 2 working days from QLD to Melb. And great price too!

Also going to have a go at rebuilding the front caliper as soon as the rebuild kit gets here.. hope it aint too hard to do.
 

·
Registered
Joined
·
1,247 Posts
Class vid. Never knew that shit could be done on a 125. Now Im too old and too scared to attempt any of that shit!

Nice project too man, the bike looks like something out of mad max 2. Rebuilding the caliper will be a piece of piss after doing all that! As regards the fuel cap, can you just hammer a screwdriver into it? (I know, im all about the finesse)
 

·
Registered
Joined
·
1,327 Posts
Discussion Starter · #18 ·
not much to update. Just been hitting the stunt spot, giving the 125 abuse and it's taking it like a champ!

The other day decided to f*k off the rattlecan tyga straight through and made up/welded a flange to suit an OEM MC22 muffler:



Sounds pretty damn good actually! And the noise is now bareable. No more BAARP BARRRP BAAAAAARP BARRRRRRRRRRP of the 125cc single cylinder!
 
1 - 20 of 29 Posts
Top