Hanging revs on a 99wr400


7 replies to this topic
  • dirtsurfer1

Posted June 03, 2004 - 05:10 AM

#1

Did anyone ever find out what was going on with the hanging revs. My bike runs great but revs hang some of the time. I notice it while coming down hill some of the time. Just seems as if the gas is on a bit. :thumbsup:

  • holeshot426

Posted June 03, 2004 - 12:42 PM

#2

Probably lean condition. Try turning OUT your fuel screw to richen your pilot circuit up a bit. Look into doing the ACV mod - may help in dialing in your fuel screw.

  • N7SLC

Posted June 03, 2004 - 01:10 PM

#3

ACV mod? :thumbsup:

  • Frostbite

Posted June 03, 2004 - 03:27 PM

#4

Check the throttle slide plate. It may be cracked and not slipping down in it's pocket every time you close the throttle. Mine broke and I've heard a lot of others have too. Check with a magnifying glass, the hairline crack is hard to see.
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  • PumpkinHumper

Posted June 03, 2004 - 03:45 PM

#5

Did anyone ever find out what was going on with the hanging revs. My bike runs great but revs hang some of the time. I notice it while coming down hill some of the time. Just seems as if the gas is on a bit. :thumbsup:


When is the last time you checked your valves or put rings in it??

My 99 yz400 had similar symptoms. My fix was new rings and shim the valves. Problem solved.

  • matatac

Posted June 03, 2004 - 04:03 PM

#6

I did the ACV mod, replaced all vacuum hoses, changed the intake manifold (possible hole), changed the rings, did the timing shims, removed the hot start (in case it was leaking) adjusted all the mixtures, replaced the slide, did the fuel 'squirt' adjustment, replaced the throttle cables (possible sticking) and even replaced the throttle assembly and the idle still friggin hangs!!!!! It will stay at 2700 to 3400rpm for 20sec and then returns to idle. If I let my clutch out to load up the engine, it returns to idle instantly. I put my friends carb in and the problem is gone.

Any more ideas guys?/ I am desperate. My good carb was taken by someone who wanted it more than me. I'm also thinking if I should get the Edelbrok or FCR2.

Sorry, off topic but any feed back on which is better?

  • PumpkinHumper

Posted June 04, 2004 - 02:06 AM

#7

Dude I am tellin ya. My yz400 had the exact same problems.

Putting new rings in it (I was on the origional 4 year old rings) and shiming the valves (had never done that either) totally fixed the problem.

  • dirtsurfer1

Posted June 04, 2004 - 04:53 AM

#8

Thanks for the info guys. I just checked the valves and all were good(middle intake was pretty firm though). Maybe rings need to be done from what it sounds like. Mine does the same thing as MATATAC said about letting the clutch out and put a little load on it and the revs drop right away. Well, it's more bothersome than anything. Thanks again for all the help guys! ~Eric :thumbsup:




 
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