'03 Yamaha Kodiak 400 not taking throttle

[alexwv1863]

Hey everyone, I have an issue with my dad's 03 Yamaha Kodiak 400. It had been running great but he left it sitting for a short amount of time. When he started it, it ran fine for a little bit but all of a sudden it quit taking gas. I thought it may have been the carb because it him not running it. The carb ended up being pretty clean. He put it back on and after taking it off and cleaning again, I'm beginning to wonder what it could be. It'll start and idle just fine, but when you go to give it throttle, it'll die out. It sounds like it's not getting air right but idk where to look or what else it could be. I'm stumped and need to figure this out before I go crazy. Anyone have any ideas???

[Gwbarm]

It does still sound like a carb problem. The mixture screw is under a plug at the bottom front of the carb, sometimes trash will make its way in there and you have to take the plug out to remove the mixture screw to clean it. Also the emulsion tube could be dirty its under the main jet, kind of have to push on it to get it out. You might have already done that, just a thought.

[NRA4LIFE]

Check the fuel condition or better yet, just drain the tank and carb and refill with fresh. If it still bogs, pull the carb off and make sure the slow and main jets are fully open. Also, while the carb is off, make sure the slide diaphragm is not ruptured.

[alexwv1863]

Thank y'all. I've cleaned the carb twice. I guess a third wouldn't hurt. I thought it was a carb issue too and maybe we put something back in the wrong place. It's my dad's 4 wheeler and he got it off some boy, so there's some tubes hanging down that I don't know where they're supposed to go. It also has a regular petcock on it and not the factory one that has an extension for the knob to stick out under the gas tank. If that was changed before he got it, come to think of it, I believe the carb is a generic one. I don't remember Seeing Mikuni on it anywhere. If y'all think of something else I could check, please let me know. this is driving me crazy because I know it's something simple I'm overlooking. 

[Gwbarm]

Might be an unplugged vacuum tube at carb that went to original petcock

[NRA4LIFE]

If you find you have to look at the carb again, get a set of torch tip cleaners to make sure the jets are fully open. The slow jet opening will only be approximately .015"-.020" , so make sure you have tip cleaners that go down that small. The aim here is to get any goo out without making the hole larger.

[alexwv1863]

Not that this really matters, but it's an 01 not 03 Yamaha. Just wanted to make that known in case someone needing help comes across this thread later on. 

I have tried everything that I know of to get the carb to run correctly. I've used the brush cleaners, carb cleaner, checked visually after cleaning, blew thru jets, adjusted the air/fuel mixture screw both ways. I couldn't get the screen tube out that's under the float needle. In the process of trying to get it out, I created grooves inside where the belt valve slides and now the carb leaks a little because the float is sticking. I tried everything to get that little sucker out and it wouldn't budge even a little. I have given up and ordered a new carb. Even though it's a Chinese carb, I hope it'll be alright in the end. It should be here any day now. I'll let y'all know what happens when I get the new one installed. 

Thanks for everyone's help and suggestions. It's greatly appreciated. 

[Gwbarm]

Chinese carb should get you running probably have to do some major cable adjustments, don’t throw your original mikuni away, that part I think you are referring to is the needle seat I’m sure it’s replaceable I just can’t remember if it pulls out or screws out I will take a look I have a similar big bear carb

[Gwbarm]

It appears to just pull out with an O Ring to seal, item # 14, you might try spraying some carb cleaner around it and let it soak to help get it out.

 

[alexwv1863]

I'll try that with the other carb. I don't think it's a mikuni tho. So, he got the new carb, put it on yesterday and still having the same issue. It sounds like it's not getting enough gas or too much. Also, when I went thru the carb before installing it, the needle valve doesn't move up and down in the needle seat like it does on other carbs. All the float does is push in on the button on top of the valve. Is this a normal thing or not? I don't know what I'm missing. 

[Gwbarm]

If it not an original OEM Mikuni carb i would just put on the new carb you ordered and see how thats works out, it will be fine. Its not normal for the needle to not move with the float there should be a little wire holder to attach it to the float, as the float moves up and down so does the needle. Sometimes inside the seat can get a little sticky and gummy and cause it to get sticky, i put a qtip in my drill with a little tooth paste on it to polish it up a bit and do the same on the needle sides, it slides a little smoother in the seat.

[NRA4LIFE]

I reread the thread and didn`t see if you drained the fuel and added fresh. Maybe you did and didn`t mention it? If not, catch some from the float bowl in a clean container and see if is laden with moisture. With gasohol, it can suspend quite a bit of moisture before it separates. In earlier stages it just gets somewhat cloudy. 

[Gwbarm]

I always use non ethynol fuel, even if i have to drive 20 miles to get it, i have seen too many carbs ruined by it. 

[alexwv1863]

I just wanted to post saying I finally figured out what was wrong. After putting on the second new carb, it still wasn't taking throttle. So, trying to problem solve, I placed my hand on the air intake boot that's right in front of the seat between the seat and gas tank. I cupped my hand over it and it took throttle.. Took it for a test drive and realized that it needed the plastic tank cover on because it was sucking too much air into that boot and causing it to stall out. 

So if anybody comes across this thread that's having a similar issue, try putting the gas tank cover on and see if it connects the issue like it did mine.

Thank you to those who commented trying to help me figure it out. 

[Mech]

Glad you found it..  It's amazing how sensitive some bikes with CV carbs are to their intake and air-cleaner all being just right.. Too much or too little oil on the filter can bugger them up sometimes. 

[Gwbarm]

Yeah i learned that one the hard way myself, glad you got it figured out.