Hows everyone going?? I own a 94' MC22 CBR250RR and its been off the road for the last 12 months or so as the last time I rode her I had a 'life flash before your eyes moment' when I hit a small pothole on a corner with leaky shock seals, then the god damn battery shat itself and has to push start her multiple times to get her home. Has just sat in the shed since then collecting dust but the time has come to fix her up and get back on the road. Made friends with a bloke recently who does custom bike builds and is going to help me out with the new seals, chain/sprokets, plugs, led headlights, fluids etc but his expertise and custom work is done on Harleys and that type of thing. Can anyone put me in the right direction on here in regards to the following: 1- Sproket tooth count change to increase torque? 2- Speed restriction removal? 3- Increase airflow? 4- Increase fuel to match airflow? 5- Best battery to buy as replacement 6- Cooling system upgrades ie. elec fan, water pump etc Any tips and tricks to make this baby run beautifully would be much appreciated. Also need to make some friends with simular bikes in the GC/Brisbane region to ride with once shes going!! Cheers!!
Hi Hipsta, Some thoughts to consider: 1- Sproket tooth count change to increase torque? I am not aware of the availability of different sizes for the front sprocket. You could go down a few teeth on the rear sprocket which might give you a bit more torque at the back wheel but it will reduce the top speed, make it rev even higher when cruising along on the freeway and muck up your speedo calibration. 2- Speed restriction removal? Why do you want to do this? The restrictor kicks in at 180km/h, which is well above any speed limit in Australia. If you are going to take it to the track, just disconnect the speedo cable. In unrestricted form you might be able to touch 200 on a good day. My son has manged 192ish from mine at the island. 3- Increase airflow? Put a new air filter in it. Anything else is not worth the effort. You will spend forever trying to get it to run right without putting it on a dyno and spending a lot of time fiddling. 4- Increase fuel to match airflow? Only make fueling adjustments (jets, needles, etc) if you know what you are doing, have lots of time and access to a dyno. If the bike is not running 100%, i would remove the carbs, clean, put new seals in and then reinstall with new intake rubbers. Be ready for putting a lot of time in to get it all setup again. Just slapping bigger jets in it does not improve things. Trust me, I learnt the hard way. 5- Best battery to buy as replacement One that fits. Check the regulator/rectifier as these are known to kill batteries due to over/under charging. 6- Cooling system upgrades ie. elec fan, water pump etc Flush the cooling system. Put new coolant in. Clean the bugs out of the core. Check the thermo switch circuit that operates the fan. Nothing else to be done. Any tips and tricks to make this baby run beautifully would be much appreciated. Put brand new spark plugs in it. Bad plugs cause all sorts of starting running issues. Once these little bikes foul the plugs you usually have to bin them. Seriously, do not waste your time on modifications. Put the effort into restoring its condition to original spec and you will find it will go just fine. Then enjoy riding it. If you still desire more performance, sell it and buy a bigger bike. There are a number of CBR250RRs that make their way to various race tracks around Australia. They will loose out against the bigger bikes in outright acceleration and speed (as you would expect) but a really good rider (I am not one) can hold their own on twisty circuits. Enjoy. Peter.
https://litetek.co/Carb_Kit_Honda_CBR250RR_MC22.html https://litetek.co/Coolant_Kit_Honda_CBR250RR_MC22.html https://litetek.co/CoolingSystem_O-Rings_Honda_CBR250RR_MC22.html https://www.xcitebikes.com.au/cbr250rr/ https://2fiftycc.com/index.php?threads/trim-your-spark-leads.8032/ https://2fiftycc.com/index.php?threads/how-do-i-test-my-12-volt-battery-and-charging-system.1794/ More lower end zip u drop a tooth or 2 on the front sprocket or go up on the rear ( look at a stunt bike, they have massive rear sprockets) ... but dont bother as its annoying when trying to cruise at 100kph
Oops @GreyImport is correct!!!!! To get more torque at the rear you need to go up a few teeth on the rear sprocket, not down as I suggested earlier. My bad.
