XT225 FAQ - Drive Train
I have done basic exhaust modification and installed a UNI air filter and re-jetted the carburetor accordingly. The chain and sprockets are worn and in need of replacement and I was wondering what sizes you recommend. I am currently running the stock 15/45.A:
In its stock configuration, the XT is geared way too low. If you do much road riding at all, you will want to install a 16 tooth countershaft sprocket. This gives you the top speed you need. With this gearing, first is still low enough to do almost any trail work you want, but it will also give you the additional top-end you need for your paved jaunts. I know you need a new chain, but if you didn't, the 16 tooth sprocket will fit with the stock chain. If you are going to be doing almost all trail work and only have the plates so you can hop from trail to trail, you could stay with the stock 15, or even drop to a 14.
Hello, I’d like a little more launch off the line with my Yamaha TTR125E and I am willing to give up a little top end speed to do that. The bike is currently all stock. Should I drop a tooth on the front sprocket or go up a few on the back? Also, I’m a little confused because on a couple of websites riders were talking about going up a tooth or 2 on the front (with stock 49 on rear) and claimed they got a better, faster launch. That just doesn’t make sense to me, but maybe you could explain it.
My stock sprockets are 13/49 and it’s time for a new chain, so now is a good time for me to make a sprocket change in case I need to buy a longer or shortened chain.A:
Yes, lower gearing will give you better acceleration at the expense of top speed. The problem with the TTR is that 1st gear is already so low that a 1st gear launch off the line has you shifting to 2nd in only about 30 - 40 feet. Taller gearing allows you to carry first gear acceleration farther before you have to shift into 2nd making for a better race start. The same length chain will work with 12/49, 13/49 or 14/49. You might consider buying our 14/49 + chain combo and adding 12T and 13T countershaft sprockets to the order to give you a versatile gearing set up and the ability to experiment to see what works best for you. One of the best mods you can do to get a better launch is lightening the flywheel. This allows the motor to spin up faster for the start and between gears.