yz400f throttle bog

Yamaha YZ400F 1998

28 replies to this topic
  • yz400fmaniac

Posted March 13, 2016 - 10:14 AM


ok right now i am about 3 turns out and have a hanging idle and what i have read said a hanging idle means its running lean, so i need a bigger pilot jet but i dont know what size any help is appreciated

  • grayracer513

Posted March 14, 2016 - 06:20 AM


Do yo know what size you have? 

  • yz400fmaniac

Posted March 14, 2016 - 08:17 AM


it has stock pilot jet in it i ordered a 48

  • grayracer513

Posted March 14, 2016 - 08:37 AM


So you have a #45?  That should really be big enough if it's actually clear. 

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  • yz400fmaniac

Posted March 14, 2016 - 04:16 PM


Ok right now when i start the bike up, starts first kick almost always, when its cold. but when it gets warmed up after about 10 minutes i have a hanging idle and the motor is running really hot way hotter than it ran last summer i am not exactly sure what size pilot jet is in it, the guy who rebuilt the carb said he put all stock parts in it. but i can back the air/fuel needle all the way out untill it could fall out and i still have a hanging idle and i already know i dont have an air leak. also when it gets warmed up sometimes it starts first or secound kick and sometimes it starts the 50th and yes i know about the starting procedure so its not that. i am really hoping this 48 pilot jet does the trick anything else u have to add is appreciated.

  • yz400fmaniac

Posted March 14, 2016 - 04:20 PM


this is the kit he used https://www.denniski...&ad=46766398717

  • yz400fmaniac

Posted March 17, 2016 - 04:49 PM


ok i ordered a 48 jet that wasent the right one... even though the listing said it was  :banghead: but the last time I rode the bike before messing with anything I did not have a hanging idle so i think i have an air leak...etc 

  • yz400fmaniac

Posted April 07, 2016 - 06:09 AM


well i have done everything i can to that carb and still have a bog i had a hanging idle because of the idle screw, i had it set to high stock pilot works fine i am just going to live with the bog i have the bike running perfect now and it only bogs at idle and none after about 2000 rpm

  • grayracer513

Posted April 07, 2016 - 06:59 AM


And that's really about all you can expect from the older carbs.  A bog that only shows up at around idle speeds, but not while actually riding, is not worth chasing.

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