Hey guys. My son who is 10 at about 75 lbs has been riding a blaster all this summer. I bought it with 20 tires on the rear and 21 up front. It had so much bottom end that first gear was not good for anything. It had the stock gears on. I switched the front sprocket from a 13 tooth to a 14 tooth and dint notice too much of a difference. Do I have to go up another tooth in the front or change the rear sprocket ? I know one of you guys have already been down this road before. Any advice would be much appreciated. Thanks,D

 

One tooth doesnt make hardly any difference in the back. On my R6 (street bike) i changed the sprocket from a 45 to a 51 and noticed a bit of difference but for the most part one tooth wont do much.

 

Put some 22s on back of that thing. You'll have better clearance for the trails too. You may need to put that 13 back on though, hope you saved it.

 

I once heard that one tooth in the front roughly equals three in the rear. Not sure how exact that is though... I'd try going up a few hillclimbs before you change anything else. You may not have enough low end to get up any steep hillclimbs, and going any more could make it worse. I'd say try some hills first, then adjust what you need to.

 

To the original poster:

Im surprized if you didnt notice any difference from 13, to 14. IF you had gone from 13 to 15, you would have noticed a huge difference.
Probably to much for the little blaster to pull up any decent hills.

You dont need to change the rear sprocket unless you run out of chain adjustment to accomodate the larger front sprocket.
For example, if you try to put on a 15 on the countershaft, but dont have any more forward swingarm chain adjustment, (to loosen the chain)
then you will have to replace the REAR sprocket with a smaller one to get the same results. (then adjust the chain slightly tighter)

You need to go down 3-4 teeth in the rear to make roughly the same effect as 1 UP in the front.

Another factor to consider is whether or not the case/case saver will phisically fit a 15 tooth countershaft sprocket. (if stocker is a small 13)
Just keep in mind that the Blaster doesnt have that much torque, and will suffer bigtime in the higher gears and up hills with a 15 tooth counter sprocket.