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Hi everyone. I need some help. I just got a 1996 Yamaha Kodiak that I traded a couple of guns for. It's a 400cc 4x4. It will crank up and idle just fine. When I give it too much throttle, both in neutral and when actually riding, it starts spitting and sputtering. It is backfiring too. If I give it full throttle really fast, while in neutral, it bogs down and tries to die. If I ease into it, it'll rev up all the way. I can drive it down the road, but have to give it easy throttle. And even then, it'll start bogging down, regaining power for a second, and then just keep repeating till it finally just wants to die. It has a brand new fuel petcock, fuel lines, and carburetor. It also had a brand new intake boot (carb-to-head boot). But the previous owner ripped it, when he installed it. I thought that was the main problem. So I just temporarily repaired it tonight, till the new one that I ordered gets delivered, but it's still having the same problem. Has anyone ran into this before, and figured out what it was yet? Could it have possibly jumped time? I appreciate any help. Thanks!!
 

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Hi everyone. I need some help. I just got a 1996 Yamaha Kodiak that I traded a couple of guns for. It's a 400cc 4x4. It will crank up and idle just fine. When I give it too much throttle, both in neutral and when actually riding, it starts spitting and sputtering. It is backfiring too. If I give it full throttle really fast, while in neutral, it bogs down and tries to die. If I ease into it, it'll rev up all the way. I can drive it down the road, but have to give it easy throttle. And even then, it'll start bogging down, regaining power for a second, and then just keep repeating till it finally just wants to die. It has a brand new fuel petcock, fuel lines, and carburetor. It also had a brand new intake boot (carb-to-head boot). But the previous owner ripped it, when he installed it. I thought that was the main problem. So I just temporarily repaired it tonight, till the new one that I ordered gets delivered, but it's still having the same problem. Has anyone ran into this before, and figured out what it was yet? Could it have possibly jumped time? I appreciate any help. Thanks!!
Sounds like it's running to rich. Check to see what the proper main jet size is supposed to be.
You may have to go down one or two numbers.
 

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It could also be out of time. I'm not sure which engine design is in the particular bike, but some had a timing chain that would slip teeth and go out of time. However, I would check the fuel system first. Look and see if it has a fuel filter and carb bowl you can clean out. It doesn't take much debris to allow idle but falls on its face when given throttle.
 

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Run some Seafoam in the gas for a couple tanks. Check the valve clearances, compression, and as mentioned the timing.

HM
 

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I know this sounds dumb but have you checked the oil. Had a similar problem on my Side X Side oil sensor went bad , acted very similar to what you are describing. In fact that is what caused the throttle body to rip. Back firing.

Buster
 

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Sounds like my 2004 arctic cat 400. When I took it elk huntibg . acted the same way. Dropped jet sizes. It also runs better at home now also. That particular year came with a Kawasaki motor. If that doesn't help check the timing
 

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Sounds like an issue with the new carb running too rich. Either defective needle valves/seats or the wrong sized jets.

Do you have access to the old carb?? Might be worth switching back to the old one or getting new needle valves & jets (per 7mag's suggestion) for the new one.
 

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Hi everyone. I need some help. I just got a 1996 Yamaha Kodiak that I traded a couple of guns for. It's a 400cc 4x4. It will crank up and idle just fine. When I give it too much throttle, both in neutral and when actually riding, it starts spitting and sputtering. It is backfiring too. If I give it full throttle really fast, while in neutral, it bogs down and tries to die. If I ease into it, it'll rev up all the way. I can drive it down the road, but have to give it easy throttle. And even then, it'll start bogging down, regaining power for a second, and then just keep repeating till it finally just wants to die. It has a brand new fuel petcock, fuel lines, and carburetor. It also had a brand new intake boot (carb-to-head boot). But the previous owner ripped it, when he installed it. I thought that was the main problem. So I just temporarily repaired it tonight, till the new one that I ordered gets delivered, but it's still having the same problem. Has anyone ran into this before, and figured out what it was yet? Could it have possibly jumped time? I appreciate any help. Thanks!!
water in the gas will do the same.Hoot
 

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either bad gas, the new ethanol stuff is the devil and attracts water. If it has a aftermarket pipe, the prior owner may not have the right jet in the carb. All a/m exhaust require a new jet
 
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May sound stupid but check the air box entire air system. I have one on he shop that had been sitting for some time doing the same thing. Owner wanted it to run, puzzled me for days checked everything and then rechecked and then checked again. I just had the old gut feeling and in the breather tube that ran up from the box to in front of the tank below handle bars, a mouse had gotten up in there and built a nest. It would idle fine soon as I gave it fuel it would spit sputter and carry on and sometimes back fire like it was getting to much fuel. Which it would have been due to not getting proper air/fuel mixture. Just another idea. Simple problem to fix just hard to find at times!!!
 

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Discussion Starter #12
I actually just got done riding it, and I have an update. I actually got it up to around 40mph for the first time. If I romp on it in the lower gears, it'll sputter and backfire a few times, and then start picking up and going. I can get through all the gears, and get it going at around the top speed. But only if I let the rpms get up high enough, before I start gettin into the higher gears. If I don't, it'll bog down in every gear
 

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That sounds like a miss adjustment of the high speed and low speed screws.

It wants 'leaning' on the high speed, and 'richer' on the low speed (assuming it has both).
 

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Simple answer may be to make sure the air intake is clean and if it has an air filter replace it. To much fuel not enough air is the problem, check for carbon deposits on the internal throat of the carb
 

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Check fuel filter. Check spark plug. Check spark plug wires. Check ignition module. Check vacuum leak.

Check vacuum leak with an unlit propane torch. Fire up engine, let idle, aim the propane from the unlit torch at all joints and along all lengths of tubing on the intake side of the engine. If the engine speeds up there is a leak near where the propane is pointed.
 

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Discussion Starter #17
Got it running right. The needle jet wasn't set on the right notch. Found this out while I was reading the instructions to install my new Dynojet Stage 1 jet kit. Installed the new jet kit, and it's running great. Might need to tweak the air/fuel mixture screw a little bit still.
 
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