Arctic Cat 400

ATV Connection

Originally posted by: mcain2

i think i know the difference between a sport quad and a utility, but thanks for your concern. i have had several sport quads in the past and wanted something a bit more practical for the terrian we ride. i really dont see anything wrong with having a faster than stock quad. and i dont recall saying anything about noise. i have never had any trouble out of changing the exhaust and jetting in the past, i just cant find any products for arctic cats. that is why i was asking. i would just like to get the most power (not noise) i can out of my bike.

If you were planning on modding your quad, you choose the wrong model, a 500 or 650 would have been a better choice. There is pretty much nothing made for the 400 for preformance improvements. Even the few items there are are very cost ineffective. The cheapest change is a jet kit with a better air filter, but the increase is not gonna be felt by the rider.

You can go with an aftermarket clamp-on muffler, but again the power increase isn’t there and most are noisier and the noise laws are getting bad. The county south of me passed a 55 db noise limit for atvs only. To realize how stupid this is, a lot of people talk louder than 55 db.

I ride with a number of 500 thru 660 utes and on trails and twisty roads I stay up, because I get all the preformance out of my machine. The only time I can’t keep up is when we hit the long straights and the big horsepower kicks in. I can also go places they can’t because of the full IRS and the extra ground clearance. One guy wrote as follows:

RCat400 Sun January 22, 2006 7:46 PM

I have a 2005 400 auto with 400 miles on it and it has improved the more I ride it. However, like most I feel for a 400 it was lacking a little in power/speed so this is what I have done to my 400 so far and I couldn’t be happier.

I modified my stock muffler and drilled threw the baffles, it has a deeper tone at idle and is NOT LOUD while riding, I can’t hear any difference so It will not offend anyone on the trail, My buddies stock Brute is louder than my modded cat. Next I installed a KN filter with pre-filter and a Dyno jet kit @ the current settings. 136 main jet, 2.5 turns on mixing screw, needle e-clip on 4th notch.

I spent about $100.00 for these mods and all I can say is that it was money and time well spent. I have not had it on the trail yet but have done a little back yard riding and it finally feels like a 400. It really get up and goes now!!

I have the clutch kit setting in my garage and will install soon and hope to upgrade tires later! I will keep ya posted about present and future mods and appreciate all your help and time. I highly recommend what I’ve done on my 400 to other 400 owners!

Arctic Cat 400
Arctic Cat 400


I had it Dyno tested and would like to know what stock figures are compared to mine if anyone has that information.

Max power 18.66

max torque 14.22

But he didn’t dyno test before modding, so he doesn’t and will never know. Now the info I have is that the 400 has 25 hp stock. But that would be flywheel horsepower and not rear wheel power. I would be willing to bet money that he gain less than 1/8 horse if that much and may have lost some.

Seat of the pants preformance increases are almost always the riders desire for an increase and not actual improvement. Either run a base line before mods so you have something to compare to, or you have nothing to compare to except your desire for your money to have been well spent. I race a long time and did a lot of changes, some good and some bad. But I did learn onr thing important.

Alway do one change at a time, then compare. Once I changed 3 things at once and no improvement. When I when back and did them one at a time, two improve top speed by a total of 3 mph and one killed 3 mph.

Arctic Cat 400
Arctic Cat 400

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