Z400 not idling as it once did

[Newt327]

My freind has a '03 Z400 that all of a sudden doesnt want to idle as it did before. he rode it about 4 weeks ago and when he would start it he wouldnt have to give it any gas at all and it would fire right up. Now it's been sitting in the garage and you have to give it a little gas to get it to start, then it idles a little rough. What should we check first? Would the choke do this if it were stuck on?

[sd1]

if the choke cable had a kink in it or it was sticking at the carb it might......best thing he could do is take off the carb and clean it thoroughly.....could even be a partially blocked pilot jet........either way it would not be awaste of time to go thru the carb completely

[funkmaster]

This is my Z400 hes talking about.
I put a new plug in it over the weekend and it seems to run a lot better. Still does not start right up though. Requires a little blip of the throttle to start, and then it seems to idle/rev fine.

its a 2003 so it could probably use a carb rebuild. Im planning on taking it out this week for a ride so if it doesnt run good then, ill be taking the carb off for service.

Also just put on a 13 tooth sprocket and a new o-ring drive chain. Bought new Holeshot HDs for it too, so im looking forward to a good time riding it!

[yellowzo3]

You might have bad gas. Clean the carb as its an '03 and probably needs at least a little cleaning. Also drain the gas tank and make sure the petcock isn't gummed up and clogged. Buy some new premium gas and fill 'er up!

Also clean your air filter if you haven't recently. My Z400 would start up perfectly and idle all day when my air filter was clean. After riding at the end of the day I'd start it up and it would die if I left it idle for a while (just felt a little "bleh" as well) Sure enough, the filter was all dirty. Cleaned it up and it ran as good as new again :cool:

[funkmaster]

To clean the carb should I remove it and clean it? Or just run some in the tank liquid stuff through it?

I ran it over the weekend and it was sputtering and wanting to die. This is after replacing the plug so im pretty sure theres some issue with the carb being dirty or something.

Since the choke cable still does nothing i think im going to replace that as well, since its only like $30 or something.

I will also drain the tank and check the petcock for debris.
Will also clean the air filter!

Thanks for the suggestions.

[yellowzo3]

Take the carb off!! That is the only way you can really get the carb cleaner in all the nooks and crannies. It only takes a couple of specs of sand or dirt to clog your jets so definitely take the carb off to clean it. Make sure you use carb cleaner also. Do not put anything in your tank except premium gas. I've never seen people run cleaner with their gas in a quad which leads me to believe its a bad idea. Carb cleaner comes out as a powerful jet and will blast and dissolve any dirt and grime.

If your choke isn't working then that may be a problem as the choke may be stuck in the on position causing the quad to flood out all the time. You can replace the choke cable with a pull choke that screws right into the carb. I did this and had no problems and its fairly cheap too.

When you pulled the plug to change it, what did it look like?

[funkmaster]

plug was covered in black carbon.

[yellowzo3]

You're getting way too much gas (running very rich)... Your choke could definitely be stuck in the on position causing the quad to feed extra gas into the cylinder constantly. Definitely replace the choke cable or switch to a pull choke that screws into the carb.

Did you clean the air filter yet? A dirty filter will also add to your problems as the quad isn't getting enough air... This changes your air/fuel mixture and would result in the quad running rich as well.

[funkmaster]

That makes a lot of sense b/c last time i rode the quad it used a whole tank of gas where my buddys 400ex used about 1/2. This was not normal since other times we rode together gas usage was very similar.

Guess I need to pull the carb, clean it, clean air filter, and replace choke cable. Probably will need another new plug now as well.

Ill report back in once ive done those things.
Just dont have much free time right now to work on it.

[yellowzo3]

Yup! Do all of those things you just mentioned. I think your problems will be solved. I'll check back in here often to see how everything's going. Just take your time with everything and make sure you get a can of carb cleaner and the correct filter cleaner for your air filter.

[John Noftsinger]

cut cable choke off get manual choke on carb its cheap and does,t break on handlebar roll over !That what happen to me broke lever then cut cable off cleaned rust and dirt out where cable went in carb that rubber boot sometimes let and traps water. Hope for me to get yfz450 carb/400ex boot for mine this week!

make it easy on your self just go get a 400ex :devil:

[funkmaster]

It ended up being the choke lever.
I bought a new cable, and in the process of installing it I discovered that the end of the cable had pulled through the plastic piece of the lever that holds it. Choke was on full, so running very rich, explaining the fuel use and loss of power at higher RPM and loads.

I ordered a new lever, lever cover, and new grips.
In the meantime, I have the old cable zip tied to the handlebars. I will actuate the cable with a pair of pliers if I need to use the choke, but I will probably just warm it up by manipulating the throttle by hand. I also changed the fouled plug, and cleaned the air filter. Quad runs/idles MUCH better and doesnt seem to have the power loss it had when on full choke, although this weekend will be the first real trail test for the bike since these fixes.

If it still runs poorly after this weekend ill be pulling the carb for a cleaning and probably also getting the valves adjusted.