Raptor Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter · #1 ·
Hey y’all. I’m new to the forum but my daughter is 8 years old and she has been racing for 2 years now. At the end of last season I bought her a 2020 raptor 90. I quickly figured out the limits of aftermarket upgrades for this quad. After some money and a thrifty mechanic we got a port and polish done, bored to about 100cc, bigger carb, big gun exhaust etc etc. it does run noticeably better than factory but I still believe it’s holding back. Bottom end I am
Afraid it has a lag in the throttle and top end when she comes by hammer down I can hear her all over the rev limiter. The factory front sprocket is 14T and I believe the factory rear is 38T. I was thinking about going to a 15T front and 42t rear. Or staying with the 14T front and going to a 42T rear. I also would love to find a aftermarket high rev cdi or find a way to override somehow. Has anyone found such a cdi? And I am looking for opinions, advice, and help with the sprocket situation. Thanks ahead of time guys.
 

·
Registered
Joined
·
2,973 Posts
Rule of thumb
-1 tooth on the front sprocket = +2.5 to 3 teeth on the rear sprocket, and
vice versa
14/38 would not be very different from 15/42, you'de basically be adding 1 tooth to the rear, not much and not very noticeable in terms of overall gear ratio.
For more acceleration, go -1 on the front(or +3 rear), for more top end, go +1 on the front(or -3 rear).

Sorry, I can't help you with the cdi or 90 electronics, as I'm not familiar with them.
 

·
I may be getting older, but I refuse to grow up!
Joined
·
11,765 Posts
You should have a assortment of sprockets to change for different track conditions. 13T for short tracks, 15T for long straights. 14T for average tracks. Time each lap to see what sprocket is faster each time. Then fine tune with bigger or smaller rear sprockets. You'll need different chains. Stay away from "O" ring and "X" ring chains as they rob power.
Google "Sprocket ratio" chart to see what each combination will change.
 
  • Like
Reactions: Sixpack577

·
Registered
Joined
·
6 Posts
Discussion Starter · #4 ·
Rule of thumb
-1 tooth on the front sprocket = +2.5 to 3 teeth on the rear sprocket, and
vice versa
14/38 would not be very different from 15/42, you'de basically be adding 1 tooth to the rear, not much and not very noticeable in terms of overall gear ratio.
For more acceleration, go -1 on the front(or +3 rear), for more top end, go +1 on the front(or -3 rear).

Sorry, I can't help you with the cdi or 90 electronics, as I'm not familiar with them.
Yes that’s what I thought. But when she is running wide open thru a open area she is hitting the rev limiter. So I am afraid that if I drop a tooth in the front then she might hit the limiter faster right??? And I’m also afraid that if I add a tooth in the front it will kill her bottom end. I think what I am going to do is order 1 tooth bigger in front and
You should have a assortment of sprockets to change for different track conditions. 13T for short tracks, 15T for long straights. 14T for average tracks. Time each lap to see what sprocket is faster each time. Then fine tune with bigger or smaller rear sprockets. You'll need different chains. Stay away from "O" ring and "X" ring chains as they rob power.
Google "Sprocket ratio" chart to see what each combination will change.
Thanks Dezperado. That makes sense. That seems like the best plan. And who do you get your sprockets from?? Also does rear tire size effect this at all??
 

·
Registered
Joined
·
6 Posts
Discussion Starter · #6 ·
Yes, rear tire size/height/weight effects it
Ok so correct me if I’m wrong. Smaller rear tires would add even more bottom end or torque to a quad that you already dropped at tooth in the front or added 3 in the rear. And bigger rear tires vice versa?? Sorry I’m just trying to make sure and get my head wrapped around this. I know DRRs, apex, and cobras. I know cvts enough to race. But I am new to the raptor world.
 

·
I may be getting older, but I refuse to grow up!
Joined
·
11,765 Posts
Rocky Mountain ATV for sprockets and other parts.
Try +1 counter shaft sprocket, or -2 rear sprocket.
Tire pressure will make a difference too, anywhere from 4psi to 10psi, maybe more.
Walk around the pits and ask questions. What sprockets, tires, air pressure, CDI, suspension, a-arms, axle width, etc? Most should be happy to brag about what they have. Take pictures. And, read the racing rule book and set your bike to the max, or minimum. Max suspension width, max bore size, bigger carb, minimum weight, etc. If it's flat track, limit the rear suspension travel with some straps. Put the bike on a diet, remove things that aren't necessary, lights, reflectors, trim or replace long bolts. Be creative.
 

·
Registered
Joined
·
2,973 Posts
Ok so correct me if I’m wrong. Smaller rear tires would add even more bottom end or torque to a quad that you already dropped at tooth in the front or added 3 in the rear. And bigger rear tires vice versa?? Sorry I’m just trying to make sure and get my head wrapped around this. I know DRRs, apex, and cobras. I know cvts enough to race. But I am new to the raptor world.
Yes sir, that is correct.
 
1 - 9 of 9 Posts
Top