Sign in to follow this  
Followers 0
Burton157r

New WR400. Carb problems

12 posts in this topic

Hey all. I bought a 2000 WR400 last night, and everything checks out with the exception of the bike will not run w/out the choke pulled. When the choke is pulled, it runs strong with no noticable problems, even when hot. I cracked open the carb. and cleaned out the jets (which did have some sh** on them) and put it back together, but it did not fix the problem. Any ideas? Also, as far as "uncorking" the bike goes, what are the first things i should attack? I assume the throttle stop makes a big difference when ground down. I pulled out the spark arrestor, and took off the airbox cover. What is this gray wire i hear of? Thanks for the help guys

Share this post


Link to post
Share on other sites

you probably didn't clean the carb enough - did you pull the pilot jet and also count the number of turns it was set at before pulling? That's likely where your problem lies or you could have an air leak between the carb and head, so check that too.

For cleaning the carb, completely disassemble it except the TPS (Black thing) - don't remove that. Then soak it all in brake or carb cleaner, blow all passages out with compressed air.

Also clean the diaphram for the AP and all associated passages and the pin that moves the AP

Did you clean your air filter at all?

Are there any significant elevation changes from where the bike was to where it is now...

Share this post


Link to post
Share on other sites

I open it back up and found that the pilot jet was still clogged. I got it clean w/ a needle and deep creep, as far as i can tell anyway. The bike now runs w/out choke...but relatively unstable, and stalls out. Does the fuel screw need a bit more rotation? Or does it sound like it's still clogged? I'm going to try the screw tomorrow.

Share this post


Link to post
Share on other sites

My petcock is also leaking. What could this be? Bad seal? Or do i need to buy a new cock? It's leaking down into my carb and flooding it everytime the bike sits. Damn. Thanks guys

Share this post


Link to post
Share on other sites
My petcock is also leaking. What could this be? Bad seal? Or do i need to buy a new cock? It's leaking down into my carb and flooding it everytime the bike sits. Damn. Thanks guys

Xquce my bad english but what is petcock

Share this post


Link to post
Share on other sites
Xquce my bad english but what is petcock

Fuel tap.

Share this post


Link to post
Share on other sites
Fuel tap.

The carb should'nt overflow even if the fueltap is on constantly.

Sounds like needle valve aint closing properly.

Maybe you should check your floaters...?

Share this post


Link to post
Share on other sites

When you had the carb open, the pin that gets moved by the float - was it rough at the rubber head or did it look good? Also - the inlet seat needs to be clean - any dirt or varnish stuck to it will keep it open and your carb will flood and it will run like crap.

you can look up here at TT how to properly adjust the fuel screw on the bike once you have verified everything else.

Share this post


Link to post
Share on other sites

Sounds like a clogged slow/pilot jet. When you cleaned the jets are your sure you got them cleared completely? How many turns out in the idle screw?

Share this post


Link to post
Share on other sites
Sounds like a clogged slow/pilot jet. When you cleaned the jets are your sure you got them cleared completely? How many turns out in the idle screw?

Yep, i found tht the pilot jet was still clogged. Opened her up, and it was still idling terribly, but it would run w/out the choke. I opened up the fuel screw until it ran well. I believe it's nearly 3 turns open. Is this too much? The bike is running pretty much normal at this point, but it seems a little excessive to have to open the fuel screw so much. Is there something else that could be causing the need for so much fuel? I changed the oil/filter and spark plug. What is a good baseline measurement for chain slack? It gives a measurment in the manual, but doesn't say where to take the measurement from. Almost there!

Share this post


Link to post
Share on other sites
It gives a measurment in the manual, but doesn't say where to take the measurement from. Almost there!

From the top of the rear bolt holding down the chain slider on the swingarm.

Share this post


Link to post
Share on other sites
I believe it's nearly 3 turns open. Is this too much?
3 is fine but if it needs more than that you should go with a larger PJ

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0