so i know that different sized sprockes do different things like for power and stuff, but whats the theory? Does a smaller front give more power? I know how it works but if it was all the same, why arent all quads given the same sized sprockes to make then faster?

 

Smaller front sprocket= More bottom, less top.
Larger front sprocket= More top, less bottom.
Larger rear sprocket= More bottom, less top.
Smaller rear sprocket= More top, less bottom.

There are variables that effect what speed you get rather than the sprockets such as the tranny, and tire size. So for the manufacturers to get what gear ratio they want...such as top end for desert racing or low end with good take off for say mx racing they use what sprockets are needed for what speed they want. If all quads had the same sprocket size there would be allot of very screwed up geared quads running around.

 

so if i wanted acceleration go with a small front and a large back? And then what size should i get to accomplish this for the front and rear and where would i go to get this. right now i have on a 16 front 38 rear

 

No need to change the rear sprocket on your machine. If you want a BIIG noticable difference go to a 14 tooth front sprocket, if you want a good difference in take off go to a 15 tooth sprocket. These will both give you more bottom and take away a fair bit of top speed. I think going from a 16 tooth to a 15 tooth was 5-6 mph on the topend if i remember right.

 

After reading your "why to slow thread" then this one. I beleive you are geared way to tall. Meaning that you motor is not strong enough to pull that high of gearing. Making you slow off the line and through the gears. Now in theory once you get to top speed you should be blowing by your buddies, But by the time you get there the race is over. Heres my suggestion. 15front 40 rear. You will notice a very big gain in the low end snap. Careful not to get put on your azz. Some guys I know are running 15 42 which gives it some tractor like low end but you'll be shifting alot more. To go one further round file that heavy 530 o-ring chain and go to a 520 setup. You will see even bigger gains with 15 or 16 40. Just my .02

 

Don't forget tire size!

Stock gearing on the bomb is 16/40. Stock tires are 20". If you have put on bigger tires it is essentialy like gearing up which makes it even harder for your engine to pull it. I have read on this forum many times that if you put on 22" tires you need to go down one tooth in front to keep your same gearing.

so 16/40 with 20" tires is about the same as 15/40 with 22" tires.

PS Why the 38 on the rear?

 

Yep, tire size also makes a difference. Slipped my mind thanks for reminding me.

Knowing what I know now and if I was to start over again the very first thing before even a pipe and jetting I would do the 520 conversion first and shed as much rotating mass as possible including tires. We saw a solid two length gain from just the 520 conversion. We also did a conversion on Donal's wifes bike which put the hurt on Dons 700 rappy with a ct pipe and efi controller. He had to spray to beat me. Before the rappy would take the win by two to three lengths consistantly. Now its two to four length's in the DS's favor.

 

OOPS...yea i thought he had stock gearing on his ds...but yes 38 is to tall of gearing on the rear with a 16 tooth up front. What size of tires are you running? im running 22 inch tires with 15/41 gearing and it pulls hard through all the gears while topping out at 77mph. Like the others said go up to a 40 tooth on the rear and put a 15 up front.

 

Im running 17 40 on a 520 with a ODP Drag axle, 22' 8 Paddle medium buff's. Pulls Like a freight train[img]i/expressions/face-icon-small-wink.gif[/img][img]i/expressions/face-icon-small-happy.gif[/img]

 

What kinda engine mods you have? 17-40 seems pretty high specially if you have 22 inch tires.