Gearing

What gearing you guys runnin on your R's? When I bought mine it had 13t front and 36t rear. I really don't like it...I was thinkin about going to a 38t rear!

I mostly trail ride and will be dirt drag racing it this summer...300ft.

[wilkin250r]

I would assume you have a 330cc engine? A 13/36 gearing seems a little low for a 330, and 13/38 will only make it worse. Are you sure you want lower gearing? I would assume first gear is useless to you.

[dober250R]

14/38 is what i'm runnin, mostly mx.

Originally posted by wilkin250r
I would assume you have a 330cc engine? A 13/36 gearing seems a little low for a 330, and 13/38 will only make it worse. Are you sure you want lower gearing? I would assume first gear is useless to you.

Yes I have a 330...I know that 13/38 will make it even lower, but I can't even tap out in 6th with 13/36!

Do you have any suggestions?

[deathman53]

I had a 330 in my atc and with 14/38 first and second were useless, even with the same gearing and stock ported cylinder first is useless, most of the imt I ride in third and up, first and second are uselss to me, now I have a 310pv and I'm gonna have to play with gearing again. 13/36 is a bit taller than 14/38. If you want to know how to figure it out divide your back sprocket into the front sprocket and it will give you a number like lets say 2.769, which is the ratio for 13/36, the ratio for 14/38 is 2.714. the lower the number the taller the gearing. there is other factors too, what size tires are you using? I use 18" tires and they cut down on top end, but accelerate faster, larger the tire=more top end. I would think that you have something wrong if you can't tap out with that gearing, when I had the 330, it pulled in 6th, but still was more like a overdrive, another question, what year motor do you have, 88/89 have a shorter 5th and 6th, making 6th usefull. In most people 's r's, 6th is not usually usable(86/87 owners)

[JTRtrx250r]

:)

[1988R]

I like that chart where did you get it

[JTRtrx250r]

had it so long , I dont remember where I found it, Sorry its hard to read... I had to reduce the size of it to post it

You guys can probably save it and use the "stretch/skew" feature in MS paint to bring it back up to size

[brokenbones]

i run 14/38 on my esr 330 according to sidewinder when i bought my set up they have that chart on sidewinder web site 13/38 is basically the same i was told but with the 14 up front the chain will last longer

thats the info i got

my 2cents

deathman -

Yeah I forgot to mention.....I run 20" tires and I do have an 86 motor, so maybe that is why....

[YFZRob]

I started off running a 13/38 stock gearing on my ESR 310 kit. The quad was worthless in 1st and 2nd in anything but asphault and grass. I stepped up to a 14/38 and am fairly pleased. The only negative is that it is a little trickier launching on the pipe (TRX5 pipe w/ TRX7 porting) than with the 13 tooth front. Other than that, it's great gearing.

I know it's a completely different animal, but the YFZ uses 14/38 stock with 15/38 being a favorable upgrade. The only advantage the YFZ has running the same gearing is the torque down low to let the engine lug without feeling the need to downshift for power.

[wilkin250r]

Originally posted by CT_330R
Yes I have a 330...I know that 13/38 will make it even lower, but I can't even tap out in 6th with 13/36!

Do you have any suggestions?

I don't want to treat you like you're stupid, so take this with a grain of salt.

Do you know WHY quads have a rev limit? Because you have unbalanced weights and forces inside your engine, and spinning your engine faster creates more stress. Those stresses and forces will rob your engine of power, until they are going so fast that it requires all your engine power just to keep things spinning fast, and you don't have any more power to put to the ground.

A heavier piston will make this even worse.

With that in mind, it's entirely possible, in fact it's very likely, that your 330cc engine will not rev as fast as the stock 250cc, due to the larger piston. Its not surprising that you can't hit the rev limit, your engine may not have the upper RPM power.

Why is it so important that you hit the rev limit in 6th gear? You want to alter your gearing to meet certain needs, like top speed, shift points, acceleration, or whatever. Lets assume that your top speed is 72mph, and you can't hit the rev limit. Now, you change your gearing and you CAN hit the rev limit, but your top speed is still 72mph. Did you gain anything? Or worse, let's say you hit your rev limit, but now your top speed is only 68mph. What's the point?

Your rev limit in 6th gear should be the least of your priorities for altering your gearing. That doesn't mean you should keep the gearing you have now, by all means, go ahead and change it, just change it for more important and worthwhile reasons.

[JTRtrx250r]

Originally posted by wilkin250r
I don't want to treat you like you're stupid, so take this with a grain of salt.

Do you know WHY quads have a rev limit? Because you have unbalanced weights and forces inside your engine, and spinning your engine faster creates more stress. Those stresses and forces will rob your engine of power, until they are going so fast that it requires all your engine power just to keep things spinning fast, and you don't have any more power to put to the ground.

A heavier piston will make this even worse.

With that in mind, it's entirely possible, in fact it's very likely, that your 330cc engine will not rev as fast as the stock 250cc, due to the larger piston. Its not surprising that you can't hit the rev limit, your engine may not have the upper RPM power.

Why is it so important that you hit the rev limit in 6th gear? You want to alter your gearing to meet certain needs, like top speed, shift points, acceleration, or whatever. Lets assume that your top speed is 72mph, and you can't hit the rev limit. Now, you change your gearing and you CAN hit the rev limit, but your top speed is still 72mph. Did you gain anything? Or worse, let's say you hit your rev limit, but now your top speed is only 68mph. What's the point?

Your rev limit in 6th gear should be the least of your priorities for altering your gearing. That doesn't mean you should keep the gearing you have now, by all means, go ahead and change it, just change it for more important and worthwhile reasons. good post!;)

[zedicus00]

ive found on an 86 style tranny either first or sixth will be useless no matter how much u fool with it. i end up setting it up for 2 thru 6 then useing first like a granny lo gear. for showing of, wheeling, and or when i just wanna idle along an take a nap, like when im riding with my friends and there polaris's.

Ok....thanks for all your thoughts.....I have a little better understanding what I need to look into!