40 tooth rear sprocket?

[smorris1]

I have a 2005 and the gearing is 14/39. Will I notice any increase in low end with a 40 tooth rear? Also, Will I have to get the next size bigger chain? I dont want to go with a 13 tooth front because I have a feeling it will cut down the top end too much.

[slightlybent47]

What size tires are you running?

Also try this link
http://home.earthlink.net/~gellett/400ex.htm

[smorris1]

Im running 20 in rear

[smorris1]

i just checked out that calculator and with a 14/40 i lose about 1-2 MPH each gear total. Instead of 62 top its sayin 60 mph. So does that mean I gain acceleration?

[JOHNDOE83]

I run a 39t sproket for drag racing, but I also use 22in tires, I may switch it up to a 40t soon.

My gearing is 14/39 at the moment.

Just figured Id throw that out there...lol.

[slightlybent47]

Yes you will lose some top end but it will pull harder.

that calculator is pretty cool because you can change all the parameters, even the rpm's

[JOHNDOE83]

With my mods and 22in tires, with 16/39 gearing, pinned in 4th gear hits 70mph at a legitamate drag strip....and runs mid 9 seconds.

With 14/39 gearing, 22in tires, after switching to 5th gear right before the finish line, I run a 8.8 second 1/8th mile at 73mph, if that sheds some light on the subject.

It may be more confusing...lol.

[slightlybent47]

That’s why I like the calculator, cuz you can see what it will do before you spend any money.
I don’t think you can go over a 15 in the front because it will hit the case. You may be able to remove the case saver and make it work.

[slightlybent47]

Also you should measure the tire so you have an accurate size to work from.
Just because it said 20” on the side doesn’t mean it’s 20”

[JOHNDOE83]

Oh no, you can use a 16t and still use your sproket guard and will fit just fine without hitting the case.

[slightlybent47]

Ok………..someone told me you couldn’t run one that big but it sounds like they may have been wrong.

[smorris1]

yeah i rarely ever have the bike pinned in 5th. I ride 95% trails. I just want the bike to pull harder but also have that top end speed when I do need it. I think 40 will be a good set up. I just need to know if I need to get the next size bigger chain. Instead of a 520x94, get a 520x96.

[JOHNDOE83]

I usually buy chain in full length and cut it down to fit my different sproket combos, I even splice in 2 masterlinks sometimes if I need to change my sprokets on the fly.

[smorris1]

yeah im pretty sure I will need a longer chain than stock because when I bought my 250x the chain was all messed up and loose. I checked the sprockets and the rear one was a tooth bigger than stock and the chain was stock length and I could never get it to tighten right because he had two master links. Ill go with a 40 rear and a 520x96 chain. Hopefully that will give me some better low end. :)

[JOHNDOE83]

I would buy the full length regular steel chain, you dont wanna order or buy a chain thats only 2 links bigger just to find out you need 1 more link.

atleast if you have a full length you can cut it to the right size.

[400man]

im currently running a 13/36 setup on my 400ex. power wise its pretty much stock with a hmf slip-on. the gears feel stretched out alot longer than with the old gearing I had, 14/39. the acceleration feels a little weaker than before but I can whind out each gear alot more. I went with a 36t to get maximum ground clearance cause I run a sprocket and rotor guard with 450r rear brake setup. in the woods it does just fine for me, pretty much just use 1st and 2nd all the time. even on steep hill climbs I can hit em in 2nd gear and still have plenty of power as long as I get a good launch from the bottom.

[smorris1]

Yeah overall i am pretty happy with the stock gearing. I was just looking for a little more low - mid power because thats what I use almost all the time.

[smorris1]

hopefully the bigger rear sprocket doesnt hit or rub really bad on the rear skid plate.