I am having a problem on my 05' Kawa Prairie 700. I just put a supertrapp exhaust, a K&N airfilter, snorkel and am currently jetting the carbs. I can't get the stupid bike to run right. Even with rejetting and trying several different jets, the bike is still starving at about 40 mph. I am not sure what to do at this point and I hate to take the snorkel off. There has got to be somebody out there who has snorkelled a Prairie 700 before, and they have the same carbs as a Brute Force 750.

 

Have you tried running w/ the choke on to see if it gets any better? Another way to check your running condition is to remove your spark plugs and see what color they are. White is lean and black is rich.
With the exhaust you should have to go up on the main jet and possible have to shim the needle. I don't think the K&N filter is really flowing anymore than the stock one though. You may want to switch back to a foam filter. True, K&N filters normally flow better than stock paper filters but I haven't seen one beat a foam filter.
The first thing you need to do is find out if it is running lean or rich though. Check the plugs and post back.

 

Just to elaborate on what melloyello said. Get to the speed and throttle postion where it's running the worse and hold it steady there. Once there slowly apply the choke. If it gets better your lean if it gets worse your rich. You will have to shim the needles to get it right. The best thing to do is take it to a dyno and have it tuned in. Then you know it's right no guess work involved. Not to sound like a know it all or anything but unless the changed the prairies carbs they're not the sam as the 750. The 750's are bigger and sit in the bike a little different. Let us know what you find out.

 

Well, just wanted to give an update on the situation. My mechanic ended up putting on a 2" snorkel for the intake so that there is less restriction. He was on the phone with DynoJet to try and help him figure out the solution to the problem and it turns out that the needles were not designed to handle a snorkel, they were designed to be used with a stock air box set-up. WIth the 2" snorkel it seems to do a little better, but the DynoJet people told him to put a 90 degree elbow on the end of the snorkel and turn it backwards so that you don't get a ram-air effect at higher speeds. Dynojet said that the ram-air makes something in the carburator flutter when it shouldn't, but it doesn't run great with it turned backwards. When giving it some gas, maybe half throttle, at a dead stop, it bogs down like it is struggling to get that air moving. It seems like it is the initial pull of air that it struggles with. Once the motor gets moving it is ok. But it seems as though the new set up with the snorkel and rejetting, has given it some low end power but mid and high it stuggles a little. The big problem is when you want to change speeds quickly and you put the hammer down....doesn't matter if you are going 30 or 5 mph, it stuggles when it is demanded to change RPM's quickly. Also, when accelerating at a moderate pace, it sputters at 15 and 40 mph, but quickly comes out of it. I am going to try turning the 90 degree elbow around to face forward, maybe it will help the struggling cylinder get the demanded air. I was also wondering about going to brute force 750 carbs because they are a little bigger.

Let me know what you think.

 

What needle position are you using? Main jet size? Elevevation? Unless you have some radical internal mods your carbs can provide plenty of fuel for your mods once jetted correctly. I have a modified snorkle, k&n, and a supertrapp system on my 05 650bf and I am running dynojet 132/136 mains with needles at the 4th notch, 3 1/4 turns on the mixture screws at about 850' elevation. I had similar problems with mine when I had the needles set at the 5th notch, mine ran like crap. I was suprised what a differance moving the needles one notch made. Some people have better luck shimming the stock needles rather than using the DJ needles .

 

I agree totally w/ shimming the stock needles. Don't mess w/ the dynojet needles. Leave em in the box.
Also, have you tried removing the snorkel and trying it like that? This will tell you if that pipe is your whole problem.

It could be the snorkel that is doing it. I have ran into something similar b/4. I removed the stock airbox and snorkel from my Mojave. I made a 2" ID intake pipe that went behind my shock and mounted a Uni filter on it. It would not rev over half throttle w/ choke on or off or w/ the filter on or off. I shortened the pipe by about 10" and it works perfect. If you make an intake pipe that is the same diameter throughout too long the air in it tends to get confused. Take the pipe off and blow through it. If you can't feel the air out the other end you have probably found your problem. A pipe w/ no taper will cause air to lose velocity over distance.

 

if your using dynojets you must run their needles & springs stock needles will not work correctly install their needles & springs your problem will be solved

 

You can use stock needles w/ dynojet jets. You will just have to use larger jets or shim them up as the stock needles are thicker and aren't tapered like the dynojet needles.

 

We've got 138 in the front and 142 in the rear, the idle screws are backed out 2.75 turns.

 

Sorry, forgot...live in south louisiana so elevation almost 0. So should be on groove #5, not sure myself cause my mechanic did it, but I am thinking about getting in the carb and trying some things myself. Maybe shimming...