I just bought an '06 400 4x4 FIS manul recently and overall I love the bike. My only disappointment is that when I'm in some pretty thick mud, I have to keep it in Low range and in 1st gear. Now I've always kept my bikes in low range while in mud, but I haven't always had to keep them in 1st gear. I mean even if I shift to 2nd to get the tires spinning faster it lugs down. I did add 26"x9" swamplites in the front and 26"x10" on the rear, but I would think the bike could handle them. I had 27"x 12" on my old 500 and it pulled them fine. Has anyone else had this problem and is there a remedy? Maybe a jet kit and exhaust?

 

First off the 26" tires are not an upgrade. They are part of the overall problem. Larger diameter tires equals a lower numerical (an example is, instead of 4:1, you now have a 3.5:1), higher gear ratio, which means less torque available at the rear wheels (gear ratio multiplies torque). The second problem is you only have a 376cc motor (a 500 has a 498cc motor, and cubic inches equal more torque) which will only make so much torque, without a compression increase or a cc increase.

 

Mudfriendly,

How many miles does your 400 have?

The 400 gains a little more noticable get up and go with about 500-1000miles on it. Which you probably already knew from your 500.

I run the same swamplite tires on my 03 400 manual as you and I have not seen a huge loss (some, but a huge one) on power. First off I almost always use Low range crawling or mudding, towing, or pulling through thick stuff. When I need to travel faster I use high range. I have discovered that in Low range and high range the rpm's I shift at moves. Seems to me like my Low range 1st gear is a larger range than 1st gear high range.

The only time I DO notice a power loss is when I am in thick stuff and in high range.

From what you are describing I am wondering if the AC400 and AC500 engines have different tranny gears. This may explain the different shift points.

I guess I just found what rpm's and gear to use with my tires to get me through what ever I had my machine pointed at and I don't worry as much about how to make my 400 act like a 500.

I have been told that a jet kit, K&N filter, and a new exhaust does give the 400 a little more juice. That is if you can find the aftermarket items for a 400.

SJ

 

Barely 150 miles on it, SJ. And I know it's not even close to being broken in yet, but I was just alot more impressed with it's power out of the mud than I was with it's power in the mud. That's why I went with the 400 this time instead of the 500. When I test drove it, I was really impressed, but after getting it off into a little of the stuff we normally ride in around here, I'm not so sure. Maybe it will perk up. As for the tires, they're not very wide at all and not that much taller than stock. I know the 500 is supposed to have 15% more power than the 400, but I also had alot more meat on all four corners on my old bike without any problems turning it over for about seven years and several thousand miles. We'll see what happens in the next few hundred miles or so, and if I need to make some upgrades, I will. Thanks for the info.[img]i/expressions/face-icon-small-wink.gif[/img]

 

You have to remember that the 500 is 498cc and the 400 is 376cc's. Those 122cc's a lot of torque producing cc's to give up.

 

You're definitely right about that, Bear. In the mud is where that torque really comes in handy. That's one thing the old cat had that this one doesn't seem to... yet. Upon test driving this one, I noticed just as much perkiness and seemingly just as much top end as my old one. I guess I should've looked more towards torque. It's just hard to do that without any means to put the engine under a real strain. But don't get the idea that I'm dis-satisfied with my new bike by any means. When my friends and I went riding the other day, I could walk through stuff that they couldn't, just because of the ground clearance. I guess I'm just not used to it yet and maybe after I get it broken in, it'll perk up a little more. If not I'll just have to learn the right gear for the right situation, like SJ said, or look into some performance mods.

 

Ok, I'm still learning all of your special tricks to get through mud and obstacles. I have the '06 Automatic 400. When in mud, I'm usually in high, but sounds like you guys are saying you run in low gear. Should I be in low gear when in mud and do you have to watch your speed/rpms like when you have the differential locked?

Mudfriendly - I have about 450 miles on my atv and it's a huge difference with power, steering, and overall ride then when I first got it.

 

Had the same power issues with my 400 . The Kan N helped but it was never a real slinger. What it did have was great balance . The front end is always digging And yes always first gear in the deep stuff.

 

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Thanks for the info. Kaptap, I'm hoping for that kind of increase when I get to that mileage. And yes, when in mud, I would always keep my bike in low range. It's just alot better on the machine and usually gives alot more pleasing performance in sticky situations. This is especially true with an automatic. As for locking the front differential, I wouldn't even lock it in unless I needed it. I don't think the RPM's will effect it as much as speed, but a locking differential isn't designed for use at high speeds. It's simply there to get you out of a jam when you need it. So, unless I get into something that I can't or think I can't get out of with limited slip, I don't even touch it.

 

My 03 AC400 does not have a locking front diff. But, when I find myself with three tires buried and one front one spinning. I lean over the front handle bars and apply slight prressure on the brake handle and give it gas.

It usually keeps that one tire up front fron getting all the power and allows the other tires to turn. When that doesnt work, I lean or put weight over the tire spinning.

When all the above fails, It is time for the winch. AS by this time backing out is not an option.

This does not happen to me often enough to get real good at it. I usually just avoid the situation if possible. If there are other secrets or tricks there I am all ears.

SJ