how to make my bike faster?

I bought a 125 supermoto back in June, same day I cut off the old exhaust and replaced it with a yoshi can, put a cone filter on it and upgraded the main jet to a 115. my bike is currently topping at around 65mph, which isn't fast enough for me, but short of paying out a couple of grand to do a full bike test and get a bigger bike and insurance (I'm only 17 so insurance would be ridiculous), I can't think of much else to do, speed wise. there's COUNTLESS things im in the process of doing with the bodywork, but as for the engine, aside from the standard exhaust and filter, everybody seems extremely vague about what works and what doesn't. I was wondering if there was anyone who could set out a list of things proven to increase speed and power. thanks in advance :)

sounds like your getting about the best your going to get out of it , my 250 's top speed is about the same

its the fact that the wind resistance past 50 mph "piles up" the faster you go creating more and more drag

the only thing I could suggest would be a windscreen to make your bike (you) more "slippery" to allow it to slip thru the air easier


as for power , could always go with a nitrous trickle injector .......... but your risking your motor with nitro

well, I still haven't done a sprocket change yet, currently a 13 tooth at the front, but it does pull like a b**ch for a 125. thinking of putting a 15 tooth on the front, and getting a nos kit for a pitbike just for the laughs, even if it ruins the engine :D cheers for the reply :)

115 might be a bit too big for you, I don't know if I have the same engine as you or not but with a 115 main jet in mine I get reduced performance and really bad missfires. Your other options are a bigger carburettor; I have a 26mm carb (with 30mm opening) which added a couple of mph to the top speed and helps keep me at that speed as well. A bigger front sprocket would most likely help with top speed too; I have a 17 tooth front sprocket which helped with top speed, lengenthed out the gears and helped with fuel economy but you have to stay in low gears to get any acceleration power and slow speed control is harder. Your only other options are a big more hard core such as a 150cc big bore kit (which I have) and a performance cam shaft (which I have yet to fit).

it's a 112.5, not 115, sorry. I might drop it back to a 110. one of my friends is selling a 250 2-stroke race engine, might just dump that in it of its the right price. or, as you say, 150cc bore kit. did you see any performance gains with your kit? and what will the cam do? cheers

Lol a 250cc 2 stroke enging would rip the frame apart :O

I got a little performance gain from the big bore kit but nothing too amazing. As for the cam I would hope that it adds a bit of performance aswell but I haven't fitted it yet so I can't say for sure.

At the end of the day it's a 125 4-stroke. You're not going to get much out of it even if you spend thousands on it, better saving the money for your test, not to mention mods will most likely lower resale price. Stock is key with 125s ;). Ps when you get your license. Insurance will drop a ton.

cheapest thing for top speed is a sprocket change but you loose the acceleration so you need to find a good balance between a reasonable midrange grunt and top end its all trial and error with sprockets, iv had 3 sets so far to get my set up not and it does 87mph but i do have 20 bhp to play with and a full stainless DEP system, but i am 100% legal as iv done my license last year im just waiting on it tobe unrestricted next summer for a 400cc sports bike

Kennon