alright i've got a 99 prairie 400 4x4 and want to get more power out of it. I am having a hard time finding any parts for it that will increase my performance. i have a K & N filter but thats about it. I am putting titan 589's on it and want as much power as i cna get to turn them over well. SO if you guys could suggest some things i could add and where i might be able to find them i would much aprreciate it.

 

while not conversant with the 400's,
a couple of things work well for all quads & bikes..

1) stock airboxes are generally restrictive, see if you can find a automotive radiator hose that is large diameter to increase airflow into the box, or possibly ask Diamond G if the snorkel will fit on a 400..if the part # is the same for the 650 stock snorkle as it is with the 400, you probally can make something work without carving up the airbox.

2) the more air that the engine takes in, the more fuel that can be mixed with it, either a jet kit if you don't want to experiment, or try playing with the main jet (increasing the size) in small increments, on the 650's mains are 6 bux each.

3) the more fuel and air that goes in, the more it needs to come out, a less restrictive exhaust will make better power, but at a compromise to noise. either mods to stock, or aftermarket.

4) what I have noticed is when you do all 3 items performance can increase by about 20%, at least it has on my street bikes, I only did airbox & carb to the p650, still stock exhaust..but it is an improvement.

these are the cheapest and easiest places to start looking for power, after that it starts to get expensive..cams, head work, ignition work, etc...

 

DiamondG 650 snorkle does not remotely resemble the 400 one. However, surveyor is correct that you should look into whether the inlet is a restriction.

1 K&N filter flow better than foam. The 400 airbox is perfect for a K&N (unlike the 650, since I feel the K&N does not seal well). K&N protects in dust, but some say not so well in mud. Get a twin air if you are concerned.

2. Jet kit. Dynojet has one for the 400.

3.You can improve it with a white spring from erlandonperformance.com (rev a little higher). $25

4. Exhaust. I hate it when people make their quads louder. Mine is a loud as a Prairie 400 now, and as loud as a 660. I am ashamed of myself.

5. Fourstroke tech has a 500cc kit for the 400. They also do port work. I think someone has a cam for it. They may sell a higher flowing carb. I dunno. These mods can really make it spank. I believe you could keep up with stock 660's with enough of an investment, but I would rather convince you to get a 650.

 

roc,(OOPS..MASTER ROC)
if I could find a stock exhaust for a 650, I'd like to play with the mods to it, I have no problem with it..I heard yammy 650 v stars with semi gutted pipes & did not think they were loud, yes you can hear them, so I went ahead and took the rear baffles out of it. I heard the same thing on my v-4 before I did it as well..not any louder than most of the aftermarket pipes, and sounds better IMHO..but I had the luxury of hearing them before I modded the pipes, bucuase there was no going back.
I liked the pic you have with the super trapp insert in the pipe..on the street bikes I noticed that after 3 3/8" holes, in the rear baffle only, it did not get any louder, no matter what size I made them, I took the rear pipe and baffle out to give a better tone..
(it had a little wheeze to it)
I should be embarrased, but I'm not..any louder than what I have would be annoying to me on a long ride..

the p650 could be a little louder & not hurt anything, I agree..but I don't want loud(more than about 10% more) as it turns a lot of folks off, & not real businesslike for the uses that I do with the p650..I know that it works, from what alltoys said he ran on his dyno..

the only experience I have had has been with the 2 street bikes and the prarie, but ALL the airboxes were restrictive, as well as the pipes..
.
thanks for the insights..& all the help