Jump to content
Sign in to follow this  

Honda 400ex jetting issue or something else?

Recommended Posts

Recently acquired 2008 400ex, 100% stock except street legal kit and handle bar  bike has never been apart very low hours still has nubs on tires previous owner says never had a problem on ridden maybe 30 times did see some sand..  had been sitting so I assumed the bogging was bad gas/dirty carb.  I cleaned and oiled air filter drained tank cleaned filter, pulled jets cleaned with carb cleaner, replaced pilot with 42.  resembled put fresh gas starts almost instantly will idle for ever, 1/4 throttle seems fine will even pull the front tires off the ground. at about 1/2 to 3/4 starts to bog stutter shutter what ever word you use for it.  wot throttle will cause bike to stutter even more if held at 3/4 in neutral it will start to sputter continuously some white smoke then dies hit the button and it starts back up.  Pump shoots a good stream gas checked ground on battery plug comes out black (obviously rich white smoke black plug)  cant figure out why stock main is 148 elevation is 4500' needle is not adjustable.  Any help would be greatly appreciated the weekend is coming.

Share this post


Link to post
Share on other sites

Hard to say, but since you only replaced the pilot jet, I would go back and replace the main also.  Almost sounds like the main jet could be loose or maybe even fallen out into the float bowl.   I'm no expert, but rule out an air leak also by checking all the connections to the carb. It does sound like a carb issue to me.

Share this post


Link to post
Share on other sites

Well some resolution, I checked everything swapped cdi, coil &  wire, and rectifier one at a time  from a running bike problem still there.  Swapped carb off running bike problem gone, running bikes carb had a 142 main, so swapped that into the other carb problem is back.  replaced float needle and problem is barley noticeable.  Is it possible that the factory jetting is just that bad I ordered a new float, it will be here in a couple days, I didnt try air box lid off I am kind of sick of looking at it. I can run through all the gears as long as I dont hold it wide open for any length it runs great.  I am getting a slight bit out the overflow after wot.  

Share this post


Link to post
Share on other sites

He just said he swapped the main ?^ and also I'm having the same exact problems with my raptor so if any one can help it would be awesome

Share this post


Link to post
Share on other sites

allways start out replacing ALL jets off the bat and clean the carb, every orface, as best as possible.  its better to knock out the problem the first time then have to go back and revisit it. 

Share this post


Link to post
Share on other sites

allways start out replacing ALL jets off the bat and clean the carb, every orface, as best as possible. its better to knock out the problem the first time then have to go back and revisit it.

i just replaced all my jets and it's still giving me problems I've tried adjusting the air fuel screws every different position and all the pilot jets and other jets underneath the fuel bowl all stay tight right????

Share this post


Link to post
Share on other sites

Well float came in, pulled apart again, installed partial reasemble test ride problem still there, I think it may be a worn needle, and or needle jet, ordered full rebuild kit and will replace I am going to swap the needle and needle jet from the working carb while I wait to see if I can pin point that as the problem before reubilding the whole carb, I have seen this problem posted on every forum out there and most of the threads end in no resolution, I will not leave the readers hanging on this one.   


Jake did you replace the needle jet and needle?

Share this post


Link to post
Share on other sites

Okay so here is the update, after a great conversation with a local bike mechanic and one more trip into the carb.  I swapped the needle and needle jet (for those that dont know the jet that is visible from the inside when the butterfly is open that the needle slides through) problem is still there.  the needle out of the old carb (99-2005 had adjustable needles 05 to current do not), so I leaned it out 1 clip up stock is 3rd from top so I raised the clip to the 2nd notch, bike runs better not great, decided to try and lean it out a different way and installed k&n with outerwears and a whites e series I had in the garage, Bike rips like its supposed too.  The mechanic I talked to seems t think that even at our elevation (4500ft.) stock jetting (148 main) was just too rich, the local honda shop says they have not had any problems running stock jetting...Hmm For comparison I am running 170 main in my outlaw 525 (big three)  190 in a 450r (big three) both of those bikes run like beasts..Seems the whole problem was jetting too rich, I still plan to completely rebuild carb when kit comes in all new jets gaskets etc.  but for know it runs and on to modding the 700xx.....

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

Reply with:

Sign in to follow this  

  • Similar Content

    • By photonicreno
      Hi all!

       I've got an issue, one of many when it comes to bikes. I searched throughout all the pages I could find pertaining to my situation and couldn't find very much useful information.
      So the issue is, the bike has no electric start.... until it's hot enough to melt steel that is. It will bump start first time every time. But I can sit and crank the starter over for ever and it'll never start until the charger is bumped up past 200 amps. Not good.

       The story so far,
      Got the bike for 1k cash. Guy said it has no spark and no second gear. This particular guy also only ever rode newer crotch rockets. Brought it home pulled the choke, attached battery charger and she fired right up. Ran like absolute crap, but oh well I figure it's an older bike with only 10k miles so it probably needs a good carb cleaning. Took the carb apart and didn't know I messed something up until way later(didn't tighten down main jet). Oh well she runs well enough if I can get her started. Moved from California to Oklahoma. Eventually found the money to fix 2nd gear, and as I am a certified Honda small engine technician apprentice I figured it would be no big deal. Completely tore down engine to it's roots replaced 2nd, and 5th gear(because 5th gear connects to 2nd on the countershaft) dogs were worn pretty badly on both. The engine looked quite good compared to most others I've seen. Put the engine back together as per the service manual. Did all the right steps including loosening the banjo bolts to test for proper oil pressure. I even tore apart the electric starter to clean the contacts and the brushes and replace the dielectric grease. Adjusted the valves as per the service manual, replaced all gaskets, o-rings, seals, and oil filter.
       Finally after about a month of waiting on parts and reassembly I get to start her, only she doesn't. Electric start is still giving me the same issues I've always had. So I replaced the Ignition coil, CDI box, and put a new battery in, plus the starter motor rebuild. Nothing. Still cranks forever. I said what the heck and tried to push it slightly down hill and bump start it, and voila... fired right up! Once she gets hot enough and the stator charges the battery enough it'll electric start... sometimes.
       So I looked towards ignition, used a tool called ignition mate. Pretty awesome tool if you can afford it. Well while cranking the ignition mate reads the spark plug is getting 1-4kw of "spark" every cycle, well it only fires after getting up past 5kw sometimes 6-8kw. And sometimes the ignition would be intermittent as in it wouldn't give any spark at all. I cycle the ignition and it seems to soft reset the bike as it will usually give it back spark. I tested this with the new and old CDI box, the old one would never spark. Ever. So I threw it in the trash. A month later I stil l can't figure it out.
       Is there something I'm missing?

      TL;DR
      Bike won't start using electric start only bump start before and after engine rebuild
      Electric start works after pushing the starter past about 200 cold cranking amps or when hot.



       
    • By GreenMT_Rider
      30 years ago I sold my beloved 1985 CR500. I was young and needed money for a car. I had a lot of fun on that bike and some of the best dirt bike memories were made on it. Out of all the bikes I've owned it's the only one I regret selling. I've had opportunities to buy a 85 cr500 before but never pulled the trigger figuring leave the fond memories in the past. Well today I couldn't pass up the bike any longer. I found me a nice project bike to take up some free winter time. The bike is all there and it runs but most importantly it was cheap. Not the prettiest but it's mine. With lots of money and time it shall be returned to it's former glory and be ready to make some new memories.

    • By Ktm520sxrider
      Ready to seal back up





    • By Big64N
      Good condition with a long list of high end upgrade parts.
      Rekluse EXP 3.0 with cover and slave
      EVO- Ellensburg suspension tuning for 6' 200# expert rider
      Fork bleeders
      Trail-tech map switch
      Moose 1-1/8 flex bar
      CYCRA probend bar guards
      SXS skid plate with linkage plate
      Clutch and water pump guards
      Frame guards
      Fastway Evolution III pegs
      SRT Pro Armor radiator and rear rotor guards
      Acerbic Front rotor guard
      TM designs chain guides
      DID race chain
      Renthal sprockets
      Gripper seat
      FMF F-bomb header
      Dirt Tricks timing chain tensioner
      Pro Wheel, wheels
      Tubliss front and rear
      New top end and valve adjustment 60 hours old
      Many more aftermarket parts as well as spare parts and service manuals included in the sale.  Willing to include 4 sets of tires with 80% tread left for full price.
      Great bike with plenty of life left and set up for anything from single track woods to wide open dessert.
      Can hang with any of the 450's but is much easier to handle in the tight woods.
      Priced to sell at $6000.00 
      Willing to consider reasonable offers but no trades or carry.
    • By riverside21
      Has anybody purchased/used one of these Arrowhead IHA6017 cdi boxes??  I tried 2 different ones of these on a 1987 and 1994 XR200R, and the bikes won't even start.  Bikes just pop and backfire, had to put the old cdi's back on.  I noticed when I ordered the boxes they stated "advance ignition curves" in the specs.  The box is also much bigger than the stocker and won't fit in the rubber mount.  I didn't mess with moving around the timing to try and get these to work....I just sent them back.  
×