I have a 2002 Prairie 650 with over 4000 miles on it. It runs good,but it makes a putting or popping sound from the air box/carb area when idleing. It has a K&N air filter on it. Everything else is stock.I had it to a dealer and he said that it was common for the 650's. Does anyone else have a 650 that does this?

 

My 03 650 does the same thing, to the point where it pops then stalls when it first starts. Thought it may be rich on one cylinder and backfiring? Air screws need adjusting?? Anyone know why???

 

MIne does the same thing, and sometimes it only wants to fire on 1 cylinder, then the other kicks in, once it starts.

 

Idle probs are most commonly caused by 1 of 2 things (besides spark plugs and running out of gas):

1. The valves need adjusting.
2. People just turn the air screws to 2.5 or 3 turns or 3.25 because someone said to do that. WRONG! They need to be adjusted.

I found this info on an ATV website:

"When the engine is warn, turn each air screw clockwise slowly until engine slows (that will cause it to run lean and slow down). Then slowly turn counterclockwise until engine speeds up. You will reach a point where it doesn't speed up anymore. Go back to the leanest point that the engine still idles fastest. Turn the air screw 1/4 richer (counterclockwise) past the point where it begins to idle fastest. Do this procedure one cylinder at a time on engines with more than one carb."

My 650 starts very well because I have Dynojet needles and I adjusted them just right. You can adjust the stock needles richer with shims (small washers).

You have to crack the throttle to start a 650/700 because of the compression release.

Most ATV's should be a little bit cranky in the cold. If not, they may be adjusted too rich. But, it shouldn't be really crabby to start. You shouldn't get excessive popping. If you do, the needles may be lean.

If you mod your quad enough, you will also need to richen the pilot jet. I wouldn't tell anyone to do this unless they had major engine mods.

 

My P650 does this a little too.

My V-Force does this alot after adding dual exhaust, one size larger jets and TPI valve on top of my airbox. A mechanic is working on my quad right now for an insurance claim, I'm going to ask him to take a look at my jetting. I also think my carbs might be out of synch.

 

Mind did that till I replaced the choke springs then no more popping.........

 

This is about the 3rd time I have heard about the choke springs. What are they? where are they? In the carb? because my 03 650 from idle to off idle it spits and sputters, then runs fantastic at every other rpm range. doesnt matter if its cold or warm it does it everytime. I have adjusted and adjusted and it still does it.

 

Mine pops too, but once it warms up good it comes out of it! I only have 850 miles on it so far and I need to get the valves adjusted soon. I will post back when I get this done and let everyone know if it solves my popping. Also I'm going to install a P700 belt while it's in there, I'm still on the stock belt but I moved a lot of snow with it so it's getting replaced regardless of condition. Later.

 

Check the pilot screws adjustment first. If that doesn't help, and you haven't adjusted the valves lately, you may have a tight (or burnt) valve.

 

So if I had a burnt valve, what would it cost to fix that? I think I should get both my quads serviced.