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Just got a XR400, but with idling issue

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Hi guys, so I just picked up a plated '98 XR400 here in California, and it's running great for the most part. However, the issue I'm having is that it's having trouble with idling. I have to throttle it at stops to keep it running - this is even after warming it up and riding it for an hour or so the other night. I adjusted what I believe to be the idling screw right above and next to the choke, and it seems to start and idle better, but still not great. I don't have a lot of motorcycle mechanic expertise per se, but suggestions on where to start would be great. 

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Hi guys, so I just picked up a plated '98 XR400 here in California, and it's running great for the most part. However, the issue I'm having is that it's having trouble with idling. I have to throttle it at stops to keep it running - this is even after warming it up and riding it for an hour or so the other night. I adjusted what I believe to be the idling screw right above and next to the choke, and it seems to start and idle better, but still not great. I don't have a lot of motorcycle mechanic expertise per se, but suggestions on where to start would be great. 

These bikes and most other bikes for that matter have very small low idle jets that clog up very easily, and are touchy.  Thanks to the detergents in our gas, California especially, the gas clogs the jets if the bike had sat for any period of time....even a week or so could cause clogging. 

 

You have to remove the bottom of the float bowl, to access the idle jet, and while you are at it, you might as well remove the main jet as well.  Just soak them both in a stainless bowl, and then use a wire brush and compressed air to finish off the cleaning process.  Wear hand and eye protection when using cleaning solvents.  Carb cleaners are pretty harsh.

 

You can usually loosen the front and rear clamps that hold the carb to the air box and and engine side intake, and then twist the carb so it's turn on it's side and you can access the bottom end of it.  Use the right size phillips head screw driver so not to strip the on the bowl.  Usually the gaskets can be re-used without a problem, but recommended is to always change your float bowl gasket.....I usually don't though unless I have to.

 

It's really not hard to do this process and makes for some fun garage time.  Try it....but if you are no feeling it, find a good mechanic or friend to do it for you.  Good luck.

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Cleaning the pilot jet won't do you any good if the fuel screw passage is dirty. Old fuel can gum up that passage too. I'd clean it before dropping the bowl to clean the pilot.

 

The fuel screw is that brass screw pointing down at the front of the carb/bowl.

 

Watch this XR carb video.

 

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I was wondering what that screw was, guess it's the fuel screw. Thanks for the video, very helpful, Ill check back in if I run into any problems.

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