300ex Help with gearing

[Alias99]

I have a moded 300ex with exhaust airfilter and jetting and it seems like it has enough rpms to go fater then it is. It has the stock front and rear sprocket i was thinking about going up to a 14tooth in the front will that make a difference? What are u guyz running?

[Trevor]

Do you have 20 or 22' rear tires?


I am running 13/36 with 20' rears it seems to be good for trails and I have a top speed of 95 KPH. I had to use a halflink in my chain to get it to fit with this gearing though!

[Alias99]

i have 20's is that the stock gearing 13/36?

[300ex_#387]

Stock gearing is 13/38 im pretty sure, but I think stock gearing with 20" tires is perfect with the mods you listed

[Alias99]

Alright i just heard that a lot of people were going with 14 tooth sprocket in the front.

[Jonesboys]

I have a MODDED 300ex and I run a 14/36, and it pulls like no other, and it also gets to really high top speed. I had a 13/36 and it pulled to many wheelies, and it has a +3 inch swingy, and works triple rate shocks, so I put a 14/36 on it and it still pulls plenty of wheelies, when you want it to, but man it screams with a bigger front sprocket. I use Sidewinder Sprockets and Chains they are the best, in my opinion. I also run 20" HD's which are like, 21" my brother runs 22" XCT's and he has the same gear ratios.

[Alias99]

is 36 tooth the stock gearing for the back? And if i did go up to 14 tooth in the front would i have to get a master link for the chain. Would it make the chain weaker?

[Tri-valleyracin]

the stock gearing is 13/38 i have a 13/36 right now and i like it .

[bigbadbrad]

i run 15/38 with 20's and 14/38 with 22's, i had stock gearing with both for a while not enough top end though. If i were you i would do what i did just buy a 13, 14, and 15 tooth front sprocket, you can get steel ones for about 10-15 bucks a pop and you will be able to see for yourself which is best for you. and also you will be able to change your gearing for diffrent conditions.

[Alias99]

alright thx guyz but what about the chain situation do i need a new chain or just add a link or will that make it weaker?

[Jonesboys]

adding a link shouldn't make it weaker unless the chain is already worn.

[Trevor]

When I had the stock gearing with the 20" rears I was hitting the limmiter in 5th too easy. I could likely get away very easy with a 14t upfront though. With a 14t front do you have to remove your case saver?

[Jonesboys]

yep sure do

[exman]

1. stock gearing is 13 /38
2. big fast mx tracks 14/36
3. medium and supercoss tracks 14/37
4. trail and xc 14 38

[Trevor]

I don't think I will go any bigger than a 13t upfront if I have to take the case saver out. It's just not worth the cracked side case.

[drybranch]

How much difference is there whether you go up to a 14 or change the back a tooth to gain power? I am like you and I do not want to remove or shave the case saver so I was thinking of changing the rear sprocket-don't know if the skid plate would allow it though.

[Jonesboys]

You can get the 14 on with a case saver but it is tight. Sidewinder makes a 34 tooth rear put it with the 13 it will really increase top end speed, and you will still have low end power. Give the guys at Sidewinder a call they will help you out.

[Jonesboys]

you can lower the number of teeth in the rear and gain top end fewer teeth = smaller sprocket in rear no skid plate issues. If you want more bottom end you put a bigger gear in the rear. But the 300's got way too much bottom anyway. Also if you put Holeshot XCT 22's in the rear you will gain clearence and top speed. but you loose some cornering ability.

[Alias99]

hey thx guys but one more ? should i go with a lower tooth rear sprocket or 14tooth front sprocket for top speed?

[exrider4130]

stock gearing is 13/38....i wouldnt go any bigger with the front sprocket becaus you have to lose the case saver...and the name says it all....if you have 22's in the back, run a 37 tooth...if you have 20's run a 36 or 37 depending on where you want the power to be the strogest....im running 20's with a 37 tooth rear sprocket in most of the mideast races around here nad the trail are really tight...i keep it in 2 or 3 most of the time and with this gearing, those gears pull really hard...first is a little slow, fourth and fifth are drawn out and it winds up high in fifth....right at 70 mph at about 6500rpm....with this gearing i ran it at the local dragstrip and it ran a 10.3@62mph....not too bad considering i had to feather the clutch first, second and going into third...

[exrider4130]

i just read where jonesboy said you can run a 14 tooth with the case saver and thats true...but your chain rubs all the way around....this will eat a chain up in a hurry....now you can take and grind the case saver down about a 1/16 of an inch...but i wouldnt go through all that trouble when you can just do the rear sprocket.....1 tooth bigger in the front is equal to about
1 and a half teeth in the rear from stock....