Need help with Sprocket Sizes '07

[Holeshot1982]

Hey guys, need some help selecting a new sprocket size or seeing if it would be better to stick with the size I have now. The bike is a 07, only changes are a full PC exhaust

The bike came with the 13/47 combo that's so popular with the 07's. I do good to ride once a month and it usually motocross style tracks/trails. Once place we ride has more of a sand mixture and the other main place is clay. I'm not that experienced so I don't go for every jump but I usually do work up to new jumps each time we ride.

There was 2 tracks this past time that I was having issue with a couple of jumps. Both jumps were easy jumps but I felt like 3rd was not enough and 4th was to much. It could be a mind thing because my buddy was clearing them both in 3rd on my bike no problem but he's a lot more experienced. NOW....on his 06 CRF250 I was able to sail one of the jumps no problem (never tried the other) I know he has a 50 in the rear, no other mods have been made.

I love how snappy the KXF is and it does seem like it helps when we are riding in a sand mixture but I'm just wondering if you guys think the bigger sprocket size would help with making the gears longer BUT still help me get out of trouble when needed? Sorry for the long write up but I wanted to answer any counter questions that may have come up. Thanks

[D-K]

I have never heard of 13-47 being popular on any year KX. Stock is 13-48 and is suitable for faster outdoor tracks.

13-49 is what almost everyone changed to. It will suit most conditions. With a little practice it can carry third gear through almost all corners with ease and save a valuable shift on the exit of the corner.

Even with lower gearing, the 250 will jump as far as you dare with the throttle wide open until you are in the air. I promise.

[Holeshot1982]

OK, I guess I didn't look at my research enough then. I was thinking a 48 or 49 so I'll go with the 49. Thanks for the advice..

[D-K]

[Pr1malR8gw]

yeah you will like the 13/49.. even 13/50 is good also.. the 13/49 is the most used though..

[cygrace74]

if u are coming of a 13/47 ull be really happy with a 13/49 never ridden a 13/50 so i cant say

[Holeshot1982]

Thanks guys, I think the guy that owned it before me was really into Supercross, he even did that Rick Carmichael race down in Daytona a couple of years ago on it...

[Pr1malR8gw]

well if he was into supercross then he sure wouldn't have been running a 13/47.. he would be a 13/52

[fivepointnine]

I run a 49, Ill be getting a 50 here pretty soon, I need a little more drive out of slow corners for the winter indoor track

[Holeshot1982]

@Pr1mal - I only assume he was doing Supercross based on what he told me...

@fivepointnine - That's what I'm looking for is drive out of corners cause I'm slow! LOL But I also need 3rd gear to carry a lot more than it does now. Would a 50 be better than a 49 for that?

[Pr1malR8gw]

@Pr1mal - I only assume he was doing Supercross based on what he told me...

@fivepointnine - That's what I'm looking for is drive out of corners cause I'm slow! LOL But I also need 3rd gear to carry a lot more than it does now. Would a 50 be better than a 49 for that?

when you go bigger in the rear you are reducing over all speed but increasing torque. This will give you more drive on what ever gear you're are in how ever it will rev out quicker.. Mostly a 49 will allow a novice rider to have enough drive to stay in 3rd gear around most corners. A 50t would be even better in corners and would put you more towards the middle of the power band allowing a bit more explosive exit [if you're willing to crank the throttle at the apex] how ever as it's been said the bigger the rear sprocket the less over all speed and quicker the gear will wind out.. Thus requiring a shit up to 4th gear sooner and might not be the wisest choice for a "slow" rider as 4th gear even with a 50t might not be the best gear to be jumping in.. with a 13/50-51-52 4th gear wound out is still FAST and can easily get a novice rider in trouble. I can tell you right now that if I were to be running a 13/52 in 4th gear wound out will over shoot the double of laracco's leap at redbud power driving you into the face of the third tripple.. Mind you the distance from the face to the peak of the double is still around 70" and the face of the tripple is 100+ft.. It's a fine line on what you want to do I guess.. you just got to remember what you do and what gear you in for speed.. cause even though you loose speed on each gear you're ultimatly going up a gear and thus actuly going faster quicker..