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Backfiring V-Force

3K views 9 replies 4 participants last post by  twyztid 
#1 ·
My stock V-Force is backfiring thru one of the carbs and also thru exhaust, especially during idle. I reset the valves to spec, but didn't help much. Any other ideas?
 
#2 ·
just started doing it all of a sudden?

any mods?
 
#3 ·
I haven't had mine long but I have had this problem also. I don't have mine fixed yet but I may know a possible cause of the problem. You didn't really say but I will just assume this is with a cold motor start. I was told the chokes may be the problem which probably is the problem but not in the way that most people think. While watching my choke plungers with carb caps & slides removed I found that rear choke plunger would pull back around 1/3 of the way before I could notice the front one moving at all. I checked the Y-connection in the cable and the cables were all seated just fine. It looks worse than the photo when you can look straight on each hole.



As far as I can tell, the chokes should move equally at the same time. I believe what may be happening is when the choke is partially on that the front carb is a little lean causing the pop in the airbox and the rear cylinder is running a little rich causing the exhaust popping.

I have ordered a new choke cable (boy, they don't give those away!) and I am hoping that helps mine. I am not sure if your problem is similar or not but it may be worth checking into. I will try to remember to post an update to let you know if it helped mine.

Kevin
 
#4 ·
choke on I wouldn't be real concerned.... but with the choke fully closed then the 2 plungers should be equally seated
 
#5 ·
Well, the front one seats when the rear one is still open 1/3. That means when you only need a little choke until you close the choke when it is warmed up the front cylinder will be running leaner than the rear.
 
#6 ·
With these there is Choke on or off. they aren't like a honda 400ex that uses the flapper door to enrichen carb vacuum. there you can benefit from 1/2 choke, 3/4 choke.

If the chokes are off. like Monkey said. they should be seated. if they are not or 1 hangs open you got problems.

Don't be concerned with the opening of the plungers. open choke on, closed and seated choke off. as long as that is there. they are OK.

popping can be related to the gasket between carb and airbox.

also, if it is cold out. expect it to do it much more.

John
 
#7 ·
If the chokes are off. like Monkey said. they should be seated. if they are not or 1 hangs open you got problems.

Don't be concerned with the opening of the plungers. open choke on, closed and seated choke off. as long as that is there. they are OK.
[/b]
So why does it seem on mine that I need the choke lever all the way over to start sometimes but within a matter of 30 seconds or so I have to reduce the lever to around 1/2 open until it finishes warming up?
 
#8 ·
there are a # of things that can contribute to that. carb, Pilot circuit, a/f screw. were there any mods done to it before?? even though valve adjustment is right the valves can and are most likely leaky.

it is a 2004 model ??? be aware those are already coming up on being 6 years old. they were released in 2003 as 04 models.

it's hard to diagnose over the net.

Try the spark plug boot mod. it's an easy way to ensure the spark system is operating efficently,

John
 
#9 ·
I haven't had mine long but I have had this problem also. I don't have mine fixed yet but I may know a possible cause of the problem. You didn't really say but I will just assume this is with a cold motor start. I was told the chokes may be the problem which probably is the problem but not in the way that most people think. While watching my choke plungers with carb caps & slides removed I found that rear choke plunger would pull back around 1/3 of the way before I could notice the front one moving at all. I checked the Y-connection in the cable and the cables were all seated just fine. It looks worse than the photo when you can look straight on each hole.



As far as I can tell, the chokes should move equally at the same time. I believe what may be happening is when the choke is partially on that the front carb is a little lean causing the pop in the airbox and the rear cylinder is running a little rich causing the exhaust popping.

I have ordered a new choke cable (boy, they don't give those away!) and I am hoping that helps mine. I am not sure if your problem is similar or not but it may be worth checking into. I will try to remember to post an update to let you know if it helped mine.

Kevin
[/b]
I think I have solved the problem. I poured one once of Sea Foam into each carb during fast idle. I haven't ridden it yet, but the popping carb and exhaust has stopped. Must have been deposits in the carbs from sitting a while. Glad I didn't have to go thru the procedure that you described. Thanks for the reply.
 
#10 ·
Well, I am glad to hear you got yours straightened out.
 
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