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Started By
Message
New Carb, ATV won’t idle
Posted on 6/3/24 at 8:14 am
Posted on 6/3/24 at 8:14 am
2006 Kawasaki Prarie 360, the bike will start and run if I give it throttle, as soon as I let off it dies. Any ideas?
Ive messed with the idle speed screw, I tightened it all the way then loosened two turns out, same thing, then another two turns, still nothing. I’m no mechanic so any help is much appreciated
Ive messed with the idle speed screw, I tightened it all the way then loosened two turns out, same thing, then another two turns, still nothing. I’m no mechanic so any help is much appreciated
3
Posted on 6/3/24 at 8:23 am to TopekaTiger
Was it idling before you put the new carb on or is that why you put the new carb?
Is it an OEM carb? From what I've read sometimes the jets on the aftermarket carbs are different sizes. I had that issue on my Bayou 220. I swapped the jets with the ones from the old carb and it was fine. Is the idle speed screw that you mentioned the pilot air screw on the bottom front of the carb? The lil needle valve? It's easy to shear off the tip if you aren't careful when tightening it down.
Is it an OEM carb? From what I've read sometimes the jets on the aftermarket carbs are different sizes. I had that issue on my Bayou 220. I swapped the jets with the ones from the old carb and it was fine. Is the idle speed screw that you mentioned the pilot air screw on the bottom front of the carb? The lil needle valve? It's easy to shear off the tip if you aren't careful when tightening it down.
Posted on 6/3/24 at 8:26 am to TopekaTiger
I had a 99 prairie 400 that was having carb issues when I bought it from a guy. I bought an aftermarket carb kit, cleaned the carb out and changed all the parts. It still wouldn't idle worth a damn when I did that, so I ended up cleaning out the OEM jets and reinstalling them in the carb, and just used the gasket, float, etc out of the kit. Ran fine after that. I always found it weird that the coolant lines ran through the carb on that one.
Posted on 6/3/24 at 8:35 am to Loup
quote:
Is it an OEM carb? From what I've read sometimes the jets on the aftermarket carbs are different sizes.
This OP.
Also check your fuel lines, they may need to be replaced. If the fuel supply lines are gunked up due to ethanol than the carb won't get the right supply and run properly. This is more common on lawn equipment like chainsaws and weedeaters with smaller diameter lines.
I've also seen where the fuels lines fall apart or otherwise get debris in them and that causes the old carb to have issues only to change the carb and it happen again.
Posted on 6/3/24 at 8:48 am to TopekaTiger
It’s getting fuel from the main jet/needle but not the idle jet. You need to upsize the idle jet. Make sure airflow (aka filter) is how it will be when using the bike. Also run the fuel you will put in it. If the idle jet isn’t seized into your old carb, use that or at least look to see what size it is. Mikunis are marked on the top.
If you’re using an aftermarket carb they aren’t jetted properly out of the box. Jets are about $1.30 apiece so try and find what the stock size was for your bike and get a few, going up a size. The idle speed screw doesn’t increase fuel at idle, just air.
If you’re using an aftermarket carb they aren’t jetted properly out of the box. Jets are about $1.30 apiece so try and find what the stock size was for your bike and get a few, going up a size. The idle speed screw doesn’t increase fuel at idle, just air.
This post was edited on 6/3/24 at 8:50 am
Posted on 6/3/24 at 11:07 am to TheDrunkenTigah
Thanks for the info fellas... the old carb was leaking gas like crazy which is what started all this. It was also running pretty lean and needed half choke to stay idling.
The main jet is completely seized in the old carb but hopefully that's my issue. I'll go up a few sizes and replace
The main jet is completely seized in the old carb but hopefully that's my issue. I'll go up a few sizes and replace
Posted on 6/3/24 at 11:44 am to TopekaTiger
Again, the main jet isn’t the (only) issue if it won’t idle but will run at throttle. These carbs have two jets and control like this:
Idle - idle jet, always on, think of this as baseline fuel feed to the motor
Anything above idle - needle height, draws more fuel as it lifts with air flow
Wide open - main jet, sets the orifice size to limit max fuel can be pulled in
Basically, unless you’re racing, you will hardly ever notice or care about the size of the main jet. The height of the needle and idle jet size are by far the biggest factors in how it performs in that idle-1/3rd open range where you’ll usually run. Getting my idle jet size correct was the single best thing I ever did for my old fourwheeler.
Idle - idle jet, always on, think of this as baseline fuel feed to the motor
Anything above idle - needle height, draws more fuel as it lifts with air flow
Wide open - main jet, sets the orifice size to limit max fuel can be pulled in
Basically, unless you’re racing, you will hardly ever notice or care about the size of the main jet. The height of the needle and idle jet size are by far the biggest factors in how it performs in that idle-1/3rd open range where you’ll usually run. Getting my idle jet size correct was the single best thing I ever did for my old fourwheeler.
Posted on 6/3/24 at 2:56 pm to TheDrunkenTigah
Clean your original carb, replace the needle valve, valve seat. Use Yamaha carburetor cleaner.
Replace float if necessary.
Chinese carbs don’t have the same orifice sizes for your jets.
There may also be some hidden o-rings that are bad. Had this on my 1997 Kodiak.
Replace float if necessary.
Chinese carbs don’t have the same orifice sizes for your jets.
There may also be some hidden o-rings that are bad. Had this on my 1997 Kodiak.
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