Hello, I have read some of the threads here and love the feedback that has been given, so I am hoping to gain some knowledge, before I burn this machine to the ground!!!

I have owned my 400 for nearly 2 years, and for 2 years all of the people I ride with have been running circles around me. People with Eigers, which i know has the same motor, are eating my lunch. I am almost embarrased to take it out anymore. I dont want a race quad, but when we go on our hunts, and need to drive ten or fiteen miles to where we want to get, I dont want to be the one at the back eating dirt and having everyone complain anymore.

I cannot seem to find any mods or mod parts for this turd! My top speed averages about 35 to 38mph. I have hit 40 going downhill. I bought a winch with it, but i cant pull anything backwords, it wont even try to spin the tires, it has no snort . To get most places, i have to be in 4 low and have it revved up, when other machines are hitting it in 2wd. I have had it re-jetted, but it still lacks any power. If i stop on a steep incline, i ALWAYS end up backing down and re-starting. PLEASE HELP!!!

 

i think you may want to get a mechanic to look at it because i bought my 06 400 a year ago and i went 20 miles from the dealer to private land and top speed was and still is 52.

 

definatly have someone look at it. i ride withe 3 people who have the 400(auto. and manual) and not one has had any issues. the only thing they lack is taking off if we were to race, but top speed is exact which is 52mph. or near it. they go where i go and never think twice. is there air restriction some how? correct gap on plug? vent hoses clear? you said its been jetted, id re-check it just to be sure. throttle cable allowing it to open up all the way? just a few things to look at. hope you get it figured out. you also said its 2 years old. how many miles? they say after about 400-600 miles it begins to run a little better.

 

It is actually in the shop right now for a broken CV shaft, so i will definately have them look at it. It currently has about 600 miles on it, and about 120 hours. I will call them tomorrow and have check more in depth. Once i get it back, i will post an update.

 

My cat was running like crap after a weekend wheeling too. We just cleaned the air filter, return air, plug and cleaned out the belt. What a mess! Then she ran so good I rolled her. Damn! That sucks!

 

Sounds like you have some problems. Your 400 should top out someplace around 50 mph give or take a couple. But certainly not down around 35-40 mph range.

Make sure your air filter is very clean and not obstructed and not excessively oiled..
Make sure your choke is adjusted properly..
Put in a new spark plug and make sure it is gapped correctly..
Make sure nothing in dry - like the differentials, cv joints and wheel bearings..
Use 87 octane gas.
Keep your gas mixed with carb/injector cleaner and Marvel Mystery Oil (or use seafoam)
Read the link 'air-jetting'.. (possibly put in a 150 jet and get some air to it)
Adjust your valves.
Blow the carbon out of your muffler. (if you have the little plug - take it out)
Put some air in your tires like 8 in the front and 5 in the rear.
You might not out sprint an Eiger (your machine is bigger and heavier - better) but you should keep up on top end runs.

 

I too have an 06' 400 and yours does seem to be lacking power.

First check your air filter. One good day of riding and it's clogged.

Purchase a K&N air filter on Ebay. Go to ATV parts and search air filter. It's an
AC-4096 if l remember correctly. I just put one in mine and it definetly made a difference. Especially in the way it starts. AC's always seem to not want to start easily. Put that filter in and it turns right over. I noticed this once when l took the stock filter out to clean it. The motor turned right over. AC's want air!!!!

I have also tuned the motor. Change the plug. The stock plug is some crappy plug. When l put the NGK in and gapped it to it's wides setting for AC. .32 it gave it more spark. The stock plug was not even gapped to the minimum spec. Just a garbage plug they use!!!

Mileage means something too. I have around350 miles on mine and it is starting to really wake up and be broken in properly. Fuel mileage increases as well at around 300 miles.

After your first 100 miles have the valves checked and adjusted.


Start with these simple things first and see what happens. I too can reach around 50 mph with mine.

 

dntbdmb i also have a 2006 Arctic Cat 400 FIS 4x4 Auto with the Suzuki engine 376cc and Suzuki Duramatic belt driven clutch Tranny , and when i only had 191 miles on it i could get the speedo up to 35 mph on the power line right of way near my home and they were very steep hilll's at about 1 quarter throddle ; and i rode with my bother who has a 2004 Honda Rancher 350 fulltime 4x4 and a 1998 Yamaha 350 Wolfverine with full time 4x4 ! i could stay right on his tail as long as the trail's didn't have any jump's in the trail ( to most of you would call them whooptdo's , i could've stayed on his **** if it wasnt for the fact that i don't have leg's below the knee's ; lost them both in automobile accident in 1975 ! So he could stand up on the floorboard's with his leg's to absorb the landing , we ride in some rough terrain that is rocky mountainous with big rock and bolder's with very steep grade's and i can take it all in high range ! On one trail ride i was trying to keep up with my bro when i hit one of those whooptdo's i almost went over the handle bar's when my behind left the seat ; if it was comptition racing i would've receiived point's for a hand stand on the handle bar's a little faster i would've gone over the front rack and probablly gotten ran over by my own quad that scared me and i made sure to slow up when i came to the whoop's ! I haven't really had the chanch to ride any trail's were you could open it up over half throddle to see just how fast it will run ! Only 2 time's when imy brother and i rode the trail's near his home , on the way back we hit blacktop that turn's to diirt road half way to his house i would let him get about 8 to 10 quad lenth's ahead of me ; then i would hit half throddle an with in 2 to 3 second's i would right on his bumper ! On the two occation's i asked him how fast he was going , and he told me he was wide open throddle ; and both times we did this i was in 4wd to make it a fair race ! I to have heard by many on these forums have said the 400 AC really open up at 500 to 800 mile's they come alive in a big way ! But i haven't been on any trail's that you could open it up over half throddle for over a few second's at a time before you had to let off , and we went to Prentiss Copper in chatanooga TN , were the posted posted speed limit is 25 mph on all the access road's that lead to the trail's and the trail's 25 mph ; you don't know where and when they are hidden with speed radar gun's and hidden camera's ! So there's something wrong with your's for sure ; it should hit up 50 mph or better with no trouble ! Oh i forgot to say my AC 400 is all stock right down the tire's and wheel's , no mods at all to engine or anthing at all ! ....................

 

I have a 2006 AC 400 auto atv also. Top speed on it is only about 35-38 mph. For work we own a 2006 and a 2007 400 Auto Arctic Cat ATV's. They too are only good to about 40 mph...and that is wrapped out! I just assumed that they are all gutless machines. I've got stuck before to where it doesnt have the power to spin the wheels...it just bogs down. So I was surprised to see some of you getting 50 mph out of yours. Question? What elevation are you at? I run ours at 7200-11,000 feet. This could be the answer?

 

<div class="FTQUOTE"><begin quote>Originally posted by: wyomingwapati

I have a 2006 AC 400 auto atv also. Top speed on it is only about 35-38 mph. For work we own a 2006 and a 2007 400 Auto Arctic Cat ATV's. They too are only good to about 40 mph...and that is wrapped out! I just assumed that they are all gutless machines. I've got stuck before to where it doesnt have the power to spin the wheels...it just bogs down. So I was surprised to see some of you getting 50 mph out of yours. Question? What elevation are you at? I run ours at 7200-11,000 feet. This could be the answer?</end quote></div>

You may want to check into rejetting your carb or into 'dial-a-jet'. You possibly are too rich. If it feels as though it is skipping or misfiring, or bogging down at the top end there is a good chance you are way too rich. A shortcut to get an idea is to run top speed and then rapidly decrease the throttle to 7/8 throttle - if it runs smoother then you are too rich and need a smaller jet.

At your elevation I would guess that you need to go about 4 to 5 jet sizes smaller.
You might also read my post about 'air-jetting', sounds like you are a prime candidate for getting more air available for the carb.
You may also consider trying to get a 36mm carb installed, as a replacement for your 34mm.

A good Q&A is here:
http://www.dfn.com/benkaren/jetfaq.html