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xr400 sprockets

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What gears are you guys running in the trails? I want more snap outta my bike and dont want to spend a ton of cash or give up the reliability of my engine. my engine is all stock. Does taking out the spark arrester and rejetting it help much? I was thinking about going up 4 teeth in the rear. But I didnt know if that would be enough or if i should go up more.

Edited by matthoyda
forgot some things

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OK, so you're running 15/45 gearing. Drop the front sprocket to a 14. That's the same as going up 3 on the back, but cheaper to do and you'll only need to adjust chain slack. You'll notice quite a difference with just that change.

Never ride trail without a spark arrestor.

What year model XR400?

If you haven't done the Gordon mods to your bike, you can get quite a bit more snap there too. They are very cheap to do and easy to do. Look at the sticky for them at the top of this forum.

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01. Thanks for the info I am going to try it out and see how it goes.

I ran 15/45 for the last 4 years, i wish i had gone down a tooth in the front the last time i got chains and sprockets (2 years ago). It was alright, but sometimes it would have been nice if it went just a little bit slower. I have a 14t on the front and a 47t in the back. I haven't had the chance to ride it because I had to get back to college and the front sprocket hadn't come yet. I am looking forward to it.

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01. Thanks for the info I am going to try it out and see how it goes.

You can try the gordon's screw mod, but i like the way that i did it to my stock can. I took a 1 3/4" hole saw and cored out the restrictive end piece. It retains the stock spark arrestor and it really isn't that loud. I haven't had it tested but I would bet that it would pass easily. nice, low mellow tone to it. I would start with 155/55 (sea level) jets. Should get you pretty close.

P1000055.jpg

Edited by Alex 400

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Stock is 15/45, 3.00

I have been aiming at 13/48, 3.43 on our XR4s to enable climbing most anything in the coastal mountains of Oregon and enables those that like to use the engine brake effect on nasty down hills. It sure runs out of gears quickly on the fire roads, but that is probably a good thing?!

There are several sprocket combinations to arrive near this ratio. Some have voiced concern about the 13 tooth counter sprocket chewing up the swing arm chain slider and excessive wear around the small diameter. My records show that we have one stock XR4 with a 13 and I haven't heard any complaints? But, please note that our bikes do not get ridden as often as wished!!

13/45 3.46

14/48 3.43

15/52 3.47

3/ XR4s we purchased in and set up for CA had:

15/50 3.33

15/50 3.33

15/48 3.20

All that being stated, I have acquired a '97 XR4 with an Oregon Plate and am planning on using the 13/45 combo and carry a 14, 15, 16 for whatever the conditions are????

Exhaust:

I have been pleased with the combination of the stock can and silencer with a “Vortip” baffle. More snap, more noise than stock, but way less than with no baffle.

A rating chart I found somewhere online stated that the Vortip tested at 92db.

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I've been running 13/45 for nasty trails and DS work. It's pushing it for long distance DS stuff though. I'm planning on going to a 14&15/48 next.

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i am running a 13/52 up here in colorado.. not sure what the top end is but i bet it is close to 55-60 mph. have not rode this set up with my new up grades but it pulled pretty good with the gearing on a ticking time bomb motor

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i think the 14/45-47 is a good combination of low gearing and top speed.

14/45 =3.21:1

14/47 =3.357:1

My dad runs the 14/45 on his bike and it is a good compromise for mixed single track and fire roads. I like to go just a little faster than he does, so i hope that by going down a couple in the back it will put me up a gear and not in between.

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Gordon's Mods, Snorkel removed, new air filter, eight 15/64" holes drilled for 78% increase in exhaust area, 160 main jet and 58 pilot, running 14/45 sprockets for a 3.21 ratio. (Very strong) no problem pulling the wheel up in 3rd gear.

I bought this bike with 15/51 sprockets which was a 3.40 ratio (Too Low IMO) and extra chain was added. Keeping the 45t rear allows you to keep using the stock chain as TR42 pointed out earlier.

When I do something to add more power (pumper carb, bore, etc.) I think I'll go back and try the 3.0 ratio.

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Before I did my 440 kit I was running 14/47 and I liked that. I suggest the 14 front sprocket for your initial change because you're not sure how much drop in gearing you want or need. The 14 is the biggest change for the least amount of money and effort.

Ride that awhile and if you need more, then you can start going up on the rear.

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Before I did my 440 kit I was running 14/47 and I liked that. I suggest the 14 front sprocket for your initial change because you're not sure how much drop in gearing you want or need. The 14 is the biggest change for the least amount of money and effort.

Ride that awhile and if you need more, then you can start going up on the rear.

what do run now with your 440 kit?

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what do run now with your 440 kit?

Yes.. TR42, what are you running now? I'm... we're curious how the 440 bore has affected this?

14/50...:banana:

Ivan, do you have any other mods? Bigger jets or different carb. Any exhaust mods?

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I didn't touch a thing,except sprockets.

Bike was arrived with Mikuni carburetor,Supertrapp Spark Arrestor exhaust system,intake opened,changed main jet.

This mods are done by previous owner.

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I started out running the same 14/47 that I had been with the stock bore.

The 440 was way too much power for that low of gearing. I went back to the stock 15/45 gearing and that's what I run currently. It will turn and burn with that, and still climb like a goat and rock crawl.

Been thinking of trying a 15/46 or 15/47 rear on it tho. Any more and I think it would start getting too low again.

Yes.. TR42, what are you running now? I'm... we're curious how the 440 bore has affected this?

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Thanks guys, I ride around town a decent amount but I rarely need to go over 60mph. Do you think Ill be good with 14/46? Thats what I am leaning towards right now.

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I just wanted to add. I went out and did some desert riding this weekend and while i found myself in the upper 3 gears the most, it was just right for my speed and the terrain. lot of sand that i needed to power through and the gearing was great. could pull the wheel up really well in most gears and it would pull the wheel up to float across whoops pretty well. The only time i didn't like the gearing was in this one section of the enduro that had a chunk of logging road that i couldn't get the really high speed out of her, but i wasn't really going any slower than anybody else.

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