you dont have to do a bigger piston

 

????? i thought the xr70 head had a larger combustion chamber so you had to buy a dome top???

 

yes, the combustion chamber is twice that of a fiddy head. i have the pistons and race heads. shoot me a pm if yer interested

 

it would be smart but not neccesary
not for an xr head
if it was so they wouldnt it make sense that if you put an 88 kit youd have to have the head too and you dont
they sell big bores without heads and vise versa

 

and the ones with the heads come with a higher dome piston, the ones without the heads come with a smaller dome. believe me, i sell them and install them. daily.

 

Beatupgsxr i have big bore with 15 front stock rear....it seems there is still more top end to have by going to your set up and still have the tourqe down lown ?????? was this true for you?????

 

thats true fab
exactly what i was sayin

 

I just threw a 16 front sprocket on my '93 Z50 (stock is 14 tooth), still running the stock 37 tooth out back. I'm running a 88cc kit on it with the power silver stated above. With the 15 tooth it revved out way too quick (quicker than the stock motor). With the 16 tooth it's not revving out that fast, but you can recognize a serious lack of fuel delivery on the top end. 1st and 2nd gear are animals with plenty of torque even +2 on the front, but 3rd is when you start noticing problems. I'm hunting for a bigger carb now...all I want is 3rd to rip as hard as 1st and 2nd.

 

your going the wrong way on your gearing go smaller on the countershaft
or larger on the rear
1 tooth in the rear is equal to four teeth on the front

you want it to be fast go smaller on the rear
you want it to grunt for stunt go bigger on the rear

 

I'm pretty sure he was right...go bigger in the front if you want more top end

 

I thought it was one tooth in the front is like changing 3 teeth in the back

 

thats how it is on a real bike... dont see why it'd be too much diff on a 50

 

right nags
bigger in the front will make it faster
but you can only go so big then you run out of room
stk is 37 tooth
1 tooth in the countershaft is worth 4 at the rear
sorry my bad had it backwards
some say three depends

 

Fab is right here guys............. I know it too

 

1 on the rear is equal to almost 3 up front

 

Totally untrue......1 in the front eqals three and a fraction in the rear.

 

ya might want to double check that

if that were the case my 929 would have a smaller than stock rear sprocket instead of a bigger one

 

okay boys stop aguing. stock gearing...

front... 14
rear... 37

37%14 = 2.64

2.64 teeth on the rear is equal to 1 on the front. hope i cleared this up.

 

exactly

 

Are you sure thats how it works cause 49/12= 4.083 (stock gear on my kx125). Now if I went 49/15 I would get 3.26. 49/11 gets me 4.45. That means it takes 4.083 turns ont hecounter shaft make the rear move one. In the 49/15 it means it only takes 3.26 turns, givving me more top end because each revolution in front make my tire go more, but makes it harder on the motor. If I make it 49/11 it takes 4.45 turn to move the rear, makeing it slow but more torque.