2004 Xr400

[gatesy]

I found an XR400 yestarday after looking for a while...this one had rolled over the tripmeter 1 time and shows 28, for a grand total 128 miles. Exactly the bone stock unmolested bike I've been waiting for. I've read a lot of jetting posts, but most are in combination with some other mods. In my case, the bike has very old gas, so I took the carb out and cleaned it, and added fresh gas. Found the mixture screw to be 4 turns out and a jet black plug covered in soot. Also found the little white plastic "plate" that slips up over the main jet was installed upside down. After this, the bike seems to run great, but I need to let it get cold to see if it starts any better (I'm familiar with starting XR's, this one just liked to sputter and die when I got it).

The stock jetting is 142 main and 52 pilot. My question is...with no other changes from stock are these the jets to keep or is there a better setup?I'm in the Chicago area at about 600 ft ASL....so no altitude issues to deal with.

 

[Patman]

Sort of hard to tell we have no idea where you live, what temps you see, it there is an altitude issue to deal with...

In a box stock situation Honda set the bike up to be close for most folks. The only way to make it better is to learn how to do it and then adjust as necessary. No need to go crazy and try to adjust for evey 2 degree temp change and the like. Get it where it runs well and ride it.

 

[_JOE_]

You'll be able to tell if the pilot is good by tuning the fuel screw while you ride. If it continues to run better as you richen the mixture screw past 2 or 3 turns you could use a larger pilot. If you need to get a pilot jet get a few larger mains too and you can try a seat of the pants comparison there. Once you get that you can tinker with the needle to fine tune the mid range. These adjustments vary from bike to bike even if they're right next to each other. People like to swap jetting setup tips but alot of the time they don't work well for someone else. It's a good way to get to know your new buddy anyway and jets are really cheap.


Congrats on the new bike and have fun with it!!!

 

[gatesy]

Update....I let the bike get nice and cold, and it starts much easier. I need to ride it a little, as I'm not convinced this thing is even broken in at 128 miles, but it does like to sputter a little and will die when cold without feathering the throttle. The midpoint setting on the choke doesn't seem to have any effect regardless if the bike is hot or cold. Does this tell anybody anything?

 

[Ol'89r]

The XR400's are very cold blooded. They like a lot of choke on warm up and they take a while to warm up.

Make sure your pilot jet is clean. Remove it completely and make sure you can see daylight through it. Also check your valve adjustment. Even though the bike has low miles, check to see the valves are adjusted correctly. A tight valve will cause the bike to be hard to start when hot and will affect the idle.

The addition of a pumper carb will make that bike rip.

 

[gatesy]

XR400 starting

Thanks. The bike starts very easily when warm, and I've had the carb apart and know everything is clean. It also starts easily when cold, but it's taking several attempts. It will start right away on full choke, and idle very slowly...any throttle will kill it. Moving the choke to the center it will idle for 10 seconds or so, and again any throttle will kill it. After repeating this a few times, I'm finally able to use the throttle and get the revs up to get it warm. Once warm the idle is perfect. I have the pilot screw set at about 2.5 turns...maybe I need to go a little more and raise the idle a little so when it starts cold it will stay running. The pilot screw was about 4 turns out when I got the bike, but the plug was filthy and jet black. Any help or advice would be appreciated.

 

[longtime coming]

There's some help and advice right there.

 

[jb_dallas]

Pumper carbs are an expensive upgrade. I own a 2001 XR400 and the stock carb works fine when tuned properly. I pull the full choke, start it and I give it a little throttle and hold it at about 2500-3000 RPM until it is warm, half choke for another 20-30 seconds, then no choke. The bike is ready to run in about 3 minutes or so.

 

[axgrinder6]

i have had a few and i ride one now.the best thing to do is turn the air idle screww up a half a turn till warm.it should fire right up.then turn it back donw to where u like it after warm up.start every time,even in the witer months

 

[Patman]

I always give the idle knob a turn when starting from cold so the bike will sit with a higher idle and get warmed up. After 3 minutes it's usually awake and I run it back down.