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Discussion Starter · #1 ·
I have a 02 Honda trx400ex and it doesn't seem to stop leaking gas from the hose coming from the carb. I've rebuilt the carb, replaced the float and float needle and cleaned the carb thoroughly . Still leaks, only luck I have is to plug that hose, but today when i went riding the Damn fuel screw fell out and leaked More gas. All around bad luck! Lol
What else can I try doing? I'm just thinking I need a new carburetor...
 

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Check and re-check the float level!

Is there anything else I can do to try and fix my current carb? Where can I find one from a 450?

Yes. You can try and adjust the 'float level'. The float is set too low. Allowing fuel to over fill the bowl.
The result is fuel running out the 'overflow'. The over flow is there to keep a problem like your having from filling the engine with fuel. That will ruin an engine.

A small piece of dirt or crud can get between the float needle and seat. This will not allow the needle and seat valve to close. The result is a over flowing carb. If there is crap in the tank drain and flush it. Then install an in-line fuel filter.

Fuel screw? You mean the AIR screw? The screw that is adjusted outside the carb on the bottom of the carb? Gently screw it down until it just bottoms out. Then back it off 2 and 1/2 turns. (this is just a good place to start)

You need a Manual. A Clymer manual will help you with float heights, and how to set them. I have Both the Honda Factory and Clymer books. Why? because just like you I was having trouble.

You don't need a new carb. Your carb will work great.
Here is a video of the TRX400EX carb. Do NOT install the kit or low speed jet in the video. Rather, learn from his disassembly and reassembly.
http://www.trxforums.com/forums/engine-efi-drivetrain/1979-05-trx400ex-dyno-jet-kit-install.html


Great CARB. Basics video>>>
 

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Give the overflow tube a close inspection. I have seen the tube split, in which case, regardless of the float level fuel will run out of the overflow drain continuously. When working on a carb attention to detail is paramount.

If the tube is split, it can be replaced.
 

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Discussion Starter · #8 ·
Is there anything else I can do to try and fix my current carb? Where can I find one from a 450?

Yes. You can try and adjust the 'float level'. The float is set too low. Allowing fuel to over fill the bowl.
The result is fuel running out the 'overflow'. The over flow is there to keep a problem like your having from filling the engine with fuel. That will ruin an engine.

A small piece of dirt or crud can get between the float needle and seat. This will not allow the needle and seat valve to close. The result is a over flowing carb. If there is crap in the tank drain and flush it. Then install an in-line fuel filter.

Fuel screw? You mean the AIR screw? The screw that is adjusted outside the carb on the bottom of the carb? Gently screw it down until it just bottoms out. Then back it off 2 and 1/2 turns. (this is just a good place to start)

You need a Manual. A Clymer manual will help you with float heights, and how to set them. I have Both the Honda Factory and Clymer books. Why? because just like you I was having trouble.

You don't need a new carb. Your carb will work great.
Here is a video of the TRX400EX carb. Do NOT install the kit or low speed jet in the video. Rather, learn from his disassembly and reassembly.
http://www.trxforums.com/forums/engine-efi-drivetrain/1979-05-trx400ex-dyno-jet-kit-install.html


Great CARB. Basics video>>>
Oh okay thanks for the links, ill take a good look at them. I cleaned my carb and took it for a test run only to find out when I stopped that the air screw had fallen out and gas was leaking out of the hole. All these problems making me just want a new carb, how easy would it be to put in a 450r carb?
 

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Is there anything else I can do to try and fix my current carb? Where can I find one from a 450?

Yes. You can try and adjust the 'float level'. The float is set too low. Allowing fuel to over fill the bowl.
The result is fuel running out the 'overflow'. The over flow is there to keep a problem like your having from filling the engine with fuel. That will ruin an engine.

A small piece of dirt or crud can get between the float needle and seat. This will not allow the needle and seat valve to close. The result is a over flowing carb. If there is crap in the tank drain and flush it. Then install an in-line fuel filter.

Fuel screw? You mean the AIR screw? The screw that is adjusted outside the carb on the bottom of the carb? Gently screw it down until it just bottoms out. Then back it off 2 and 1/2 turns. (this is just a good place to start)

You need a Manual. A Clymer manual will help you with float heights, and how to set them. I have Both the Honda Factory and Clymer books. Why? because just like you I was having trouble.

You don't need a new carb. Your carb will work great.
Here is a video of the TRX400EX carb. Do NOT install the kit or low speed jet in the video. Rather, learn from his disassembly and reassembly.
http://www.trxforums.com/forums/engine-efi-drivetrain/1979-05-trx400ex-dyno-jet-kit-install.html


Great CARB. Basics video>>>
Oh okay thanks for the links, ill take a good look at them. I cleaned my carb and took it for a test run only to find out when I stopped that the air screw had fallen out and gas was leaking out of the hole. All these problems making me just want a new carb, how easy would it be to put in a 450r carb?
It's not hard you just need an adapter pice I would look into a crf 450 carb i run that on my ltr and it's awesome, it has super fast response, and if you so decide to replace the carb I would do the o-ring mod and ac pump mod
 

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You dont need another carb. What makes you think another carb is going to fix the problem of you not following a manual and rebuilding your carb correctly? I.E.
'I stopped that the air screw had fallen out and gas was leaking out of the hole'.
Had you followed the Honda or Clymer manuals, the air screw would not have fallen out.

Have you check'd the over flow tube like 'Here2help' suggested? Would you feel stupid if all it takes the fix your carb problems is, a .60 cent piece of tubing?
 

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Discussion Starter · #11 ·
You dont need another carb. What makes you think another carb is going to fix the problem of you not following a manual and rebuilding your carb correctly? I.E.
'I stopped that the air screw had fallen out and gas was leaking out of the hole'.
Had you followed the Honda or Clymer manuals, the air screw would not have fallen out.

Have you check'd the over flow tube like 'Here2help' suggested? Would you feel stupid if all it takes the fix your carb problems is, a .60 cent piece of tubing?
Well the reason a new carb was an option was because with the price of the Manuel and the air screw which they don't sell separately (need the whole float chamber) would be a little less than a used 450
 

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Discussion Starter · #13 ·
What? You CAN buy just the air screw. A Manual is available for 'free' in PDF file or, hard copy (but ya gotta buy the hard copy).

This is the airscrew set>>>16016-HM5-730
SCREW SET $16.17

This is where I found it>>>http://www.partzilla.com/parts/search/Honda/ATV/2002/TRX400EX+A/CARBURETOR/parts.html

Here is the PDF file for your machine's manual>>http://www.trxforums.com/forums/maintenance-important-information/251-free-service-manuals.html
What the.... I went to a few parts stores near my house and they all told me I had to buy the whole float chamber. Lesson learned lol. Thanks for the pdf
 

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Discussion Starter · #15 ·
So come to find out I was mistaking the fuel mixture screw with the drain screw. So the reason it was leaking was because I had the drain screw 2 turns out. Talk about rookie mistake lmao
 

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carb problems

I have a 99 400 ex. I have taken the carb off and cleaned it. I also had to buy the insulator that had broken, which mounts directly on the cylinder head. however I have a problem, when I push the accelerator more than 1/4 of the way the engine acts like it is getting to much gas, or could be something else, and doesn't want to go. but if I hold it at half throttle it slowly builds speed. how can I get it running right?
 
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