05 Honda 400ex question

I just bought a used 05 400ex. The guy bought it new, road it a couple times, putted around in the city on it, but never road anymore. But basically looks brand spanking new. But, in all this time, it has been sitting.

Has roughly 20 hrs on it. Only maintenance he has done was oil change and the valve job.

We picked it up, was low on gas, but ran completely fine in the drive way and up on the trailer.

Brought it home, has an idle problem. Put fresh 93octane gas in it. But just wont stay started until really warm, then its fine.

Took it to a friends place to ride this weekend. Would do fine.

But problem lays when under load, any gear. It almost sounds like its hitting a Fuel Cut. I would let out of the gas, get back into it, and sometimes it would do fine. Others it will still do it. Almost as if its dyeing out. Idle was, would rev fine no matter what, but sometimes would also die out even when riding/idling down hill.

I've replaced the spark plug, and air filter was a little wet, so dried that out, still has oil on filter.

Any suggestions? Clean carb? CDI box ?

 

Have you checked the fuel filter? You said it was sitting while it was low on gas so there may be some rust in the gas tank. Try draining the carb bowl also and see what comes out, make sure it's clean gas and not rusty looking or crudded up.

 

clean carb....pull the pilot jet and inspect it....use a torch tip cleaner on it

 

Me and a buddy both bought brand 02's and they BOTH were a pita when cold. Ran great once warmed up but when they were cold had a hard time keeping them running. We did learn a trick and I have absolutely no idea why this changed anything, but when cold, I would turn the fuel lever on the gas tank to reserve, even with a full tank and it helped at cold starts. I would flip it back to the on position after it was warm. As far as the fuel cut, IDK, but mine did seem to lag if gun it from idle. I miss my quad.

 

I was told on these the filter is built in the tank, and that it shouldnt need to be cleaned.

Thats what Im going to do this week. Pull the carb and use some Carb Cleaner on it and see what I get out of it.


Thanks for the help guys.

 

the jet is easy to get to....you are gonna need a 6mm socket driver to get it out.....be careful when revoming the carb and clean all around it best you can before removal
keep us updated man

 

Just got back from the car wash, cleaning it all up for removal maybe tomorrow or tuesday maybe.

But Ill defiantly post up what it is. I hate reading threads where someone doesnt post up what the fix ended up being.

 

definitely check all your jets. sounds like your pilot might be a little bit clogged up. If thats not it, it sounds like it just needs to be re-jetted.

Start with your main and lean it or richen it depending on what the plug looks like (black=rich, white=lean).

After that, tune your needle by raising or lowering it. This will help with bottom and mid powerband.

Then adjust your air(or fuel) screw. This will help mostly with bottom end and slightly on top.

It's kind of a pain in the ass, but once you get it dialed, it's totally worth it.

Let me know if you have any more questions.

 

id go through the carb
as stated above
i use seafoam you can get it at your local parts store works great ..

 

I'm not sure that your quad has a fuel filter at all. It wouldn't be a bad idea to buy and install an inline fuel filter. It should have a fuel strainer in the tank but I don't think it has a fuel filter per say. Not 100% positive on that though.

 

i bet the float bowl is stuck... i had the same problem and its back now the carb is leaking out of the vent tubes and into the air box and that carb is a pain in the ass to take off

 

Just got the carb off. Took the bowl off. Thing is COMPLETELY clean. Not even a piece of dirt in there...

So now Im lost.

If i'm not mistaken(don't do carbs too much) But once the bull came out, the copper piece at the bottom that the needle slides up and down, is the jet, Correct. It has a "148" stamped on it.

But after I got it off my truck a couple hours ago, ran it up and down the street. And it didnt do it at all though. But I was out for no more then 1 minute, then pulled it into the garage as I had to get to my pool league.

 

There's more than one jet in a carb. The one that you're talking about with the 148 is the MAIN jet. There is also a pilot jet. It's going to be towards the side of the main in a "tube" that goes up vertically towards the top of the carb. You'll need a fairly small flat-blade type screwdriver to get up in there, and then GENTLY turn the jet out. This is the pilot jet. Make sure that it is absolutely clean. Even take a wire brush and poke a single wire around inside. Use carb cleaner. Reassemble and try it.

As far as a filter, yours does not have a built in filter. The "filter" in your tank is more of a strainer, keeps big pieces out but none of the small stuff. Buy a 2.00 in line filter and put it on. Saves a lot of work, trust me Also, check inside your tank with a light and see if you see any rust. If you do, that would be a good sign that you need to get it creamed and go completely through your carb. That stuff get's everywhere and clogs everything right up.

If this doesn't do the trick, you might want to check your valve clearances. Look up the specs for it (I'm too lazy right now ) and do a cold check at top dead center. Those motors are fairly sensitive to out of spec valves and that might be your answer as well.

Good luck!

 

It looks clean because you ran it already, your pilot jet will still have stuff in it, pull it out, use a copper wire to clean it. or you could just fill up the tank, add some seafoam and ride it til it's amlost empty.

 

Well I live in the city, so cant get the quad out for too long. But made a 2 min trip up and down my street, seems to be running fine for now. Ill try to get it out again the next week or two on some trails and ride again.

Thanks for all your help guys !! Much appreciative.

 

Any one think the CDI box could be the issue ?

 

i still need to mess with the one i have i think im goint ask my buddy if he just wants to sell it its just wasting away and runs SICK ( in a good way)

 

clean out the carb, not sure if it was already said but if it was sitting the gas probably got gummed up in the carb

 

its not the cdi box, take the carb off take the bowl off clean it with carb spray, take out all the jets clean everything possible in the carb with carb cleaner, also if its all stock make sure it still has the stock jetting and needle position