Not sure on the YZ sprockets, but www.bbrmotorsports.com sells a wide selection of aftermarket front and rears along with higher quality chains. I believe they are all on sale right now.
Speaking of sprokets on a TTR125, whats a good combo to go with to get some usefullness out of all 5 gears. Takes all of about 4 seconds to get to 5th, and not long to tap it right out, how much more will a stock TTR125 take without making first too tall?
I have made some simple (and cheap) modifications to my wife’s TTR125L some of which helped it to pull a one tooth larger front sprocket. It still has the stock rear sprocket and first is still plenty low.
Powroll thrust chamber ($29.95) – very little difference in exhaust sound level but also very little difference in performance. It looks pretty neat on the end of the exhaust though. I probably would not buy another one.
Drill four one-inch holes in the top of the air box (free). This made a HUGE difference but it ran lean afterward so be careful.
Larger main jet (about $10.00) to compensate for the better air flow (110 if my memory serves correctly).
It is a different bike now with the taller gearing and better performance. Much less shifting, better top end, and much snappier.
Early YZ 80 sprockets will fit the rear but the chain is a 420 on the early YZ's and TTR runs 428, thats a bigger chain. I think Sprocket Specialists as well as BBR in USA do other sprockets. Other parts of the world are a bit limited (like Australia) in what you can get. The front sprocket off XT125 and a few others will fit. The big wheel stocker can easily pull one more tooth on the front unless you are real big.
We have two TTR125L's. One has a 14 tooth countershaft sprocket which works well for my wife at 118lbs. My eleven year old has a 15 tooth sprocket which allows him to use his full gear box while trail riding. He is faster than the wife and weights about 85 lbs.
Opening up the air box helps, as does opening up the exhaust outlet tip. I modified both exhaust tips to increase the outlet diameter to 1.1 inches. This made a big difference allows me to still run the spark arresters, and the bike is not excessively loud.
We have a Powerroll thrust chamber on the boys bike and I really cannot tell any difference in performance with it. At our altitude of 5000 + feet we needed to jet down the bikes. Run 97.5 MJ during the summer and dropped the needle clip one position.
Sprocket specialist and PBI both make sprokets for this bike. Later.....
Good info. I brought a 15 t front sprocket and hadn't got around to trying it on the big wheel. Ryan weighs about 90lb so this weekend hes racing so I will try it out in practice. His bike is well modified so if a near stocker can pull a 15t it should work on his.
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