Luedecke2009

Ok I have a 99 YZ400 F Looks like stock sprocket size is 14 49. Has anyone changed the ratio and if so what did you go with and how did it help or hurt? I am going through my bike and am replacing parts due to the age also am going to be rebuilding the suspension. The front I have no problem with the rear I know nothing...any help on rebuilding? Take is somewhere? Swingarm bushings brand??? Thanks for any input..

tjscott2012

yes, when you change sprockets remember, putting an extra tooth on the back helps torque but hurts speed +1 taking off a tooth on the front helps torque but hurts speed +3. and vice versa

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Luedecke2009

Well this thing definately isnt in need of more torque!! Should I drop a tooth in back for more top end 48 14?

turtlemann14

dropping a tooth in the rear results in higher speed and less torque

it has 14 in the front and 49 in the rear?

how fast are you looking to go? my 250 is running 14:50 and will go ~60-65

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tigmaster

If you want noticeable torque then drop a tooth in the front or go up two or three in the rear. Going up in the rear is the best way to do it but the front is a cheaper solution.

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turtlemann14

your skimming again... he said it doesn't need more torque lol

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Luedecke2009

Its plenty fast and it has plenty of torque just wanting input on anyone changing gear ratios positives and negatives. I am going to do the chain and sprockets and probably go with the stock setup unless someone has some input that has tried other gear ratios.

gscx

yea just use stock gearing, for chains i would use the renthal, for the rear sprocket i would use the sunline and then for the front sproket just get a cheap one, fronts are steel any way, and just use pivot works for your bearings and rebuild kit for the forks. but im with you on shocks, i have no idea, i need to change the fluid in mine too

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turtlemann14

well, where do you ride

you turn your gearing so that you can use more of your gears keeping you bike at peak power more

say you are going to be riding in tight trails you want a higher ratio so that you can get higher in the gears 4th 5th 6th
if your riding in a open area you want a lower ratio so that you can travel at high speeds and not top your bike out rpm wise

stock is usually fine but if your racing and need that little boost you tune your gears

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Luedecke2009

I have a wide variety of riding terrain...Sandy and open, rocky and tight, my main goal is to get the best of both worlds plenty of torque (which it has) and plenty of top end which in the open sand dosent seem to be as much as it could have.

I have been away from dirtbikes for 20 years and am re learning everything, I do appreciate all the help from everyone...For the gearing I may keep it stock for now which for my level of riding should be fine...

Where is the best place to purchase replacement parts, I have searched ebay and have found some but not all....

Thanks again for your help...