New WR400. Carb problems


11 replies to this topic
  • Burton157r

Posted July 04, 2008 - 09:53 AM

#1

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

  • matt4x4

Posted July 04, 2008 - 10:35 AM

#2

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...

  • Burton157r

Posted July 07, 2008 - 07:01 PM

#3

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.

  • Burton157r

Posted July 07, 2008 - 07:03 PM

#4

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

  • swede426

Posted July 07, 2008 - 07:12 PM

#5

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

  • SXP

Posted July 07, 2008 - 07:52 PM

#6

Xquce my bad english but what is petcock



Fuel tap.

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  • swede426

Posted July 07, 2008 - 08:07 PM

#7

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...?

  • matt4x4

Posted July 08, 2008 - 04:39 AM

#8

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.

  • byggd

Posted July 08, 2008 - 02:12 PM

#9

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?

  • Burton157r

Posted July 09, 2008 - 07:44 AM

#10

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!

  • SXP

Posted July 09, 2008 - 08:59 AM

#11

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.

  • byggd

Posted July 10, 2008 - 03:46 AM

#12

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




 
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