Help Tuning, no idle

[bandit88]

Hey guys,
A couple weeks ago I picked up a 91 KX500.  Bike had been sitting for a couple of years and needed a little tune up.  I am running into an issue with it running pretty poor down low and not wanting to idle. Its a bit odd.  To get it to idle at all I have to have the idle adjuster screw all the way in.  It acts very rich and starts first kick when cold without the choke.  When first started it idles fine and high and soon loads up and idle speed drops.  Once up to temp it idles for 5 seconds then turns off.  I keep leaning the pilot jet and am at the point that there is definitely something wrong.  I am at 5000ft, jetting so far is: 40 pilot, 155 Main, OEM needle and slide, top clip.  2 turns on air screw.  Runs good wide open.  I am running VP110 with Motul 800 at 36:1.  Troubleshooting done:
-Carb is clean
-Float height is good
-New spark plug
-New AMR ignition coil, with NGK boot and wire
-Flywheel looks good,
-Stator coils test to spec
-New oil in transmission, Redline 80w
-New UNI airfilter
-No transmission oil lost
-No residue in flywheel cover
-Fresh top end, good compression
-as far as I can tell kips is carbon free and operates correctly
-New OEM fiber reeds
-Piston installed in correct dirrection

At this point I am a little stumped.  I keep thinking ignition but everything tests good and spark is a nice blue color.  Anyone have any ideas or suggestions? Thanks

[alward25]

52 pilot and a 160 main is what I ran last time I ran from 4k-7k ft.  I would definitely go up on the pilot.  Sounds like it is not getting enough juice down low.  I would still look at going up on the main.  What exhaust u running?

[bandit88]

Thanks for the response.  I was running a 55 pilot and kept stepping down from there.  Would 4 stroke really bad down low and has been getting a little better leaning it up.  Still starts first kick without choke which tells me its rich and something isnt right.  Pipe is a FMF Gold series with stock silencer.

Thanks

[Friar-Tuck]

     I read you are not experiencing a loss of trans oil, however It really doesn't take a whole lot of oil to migrate into the crankcase to foul out your plug.
   Run the bike until it stalls out.    Pull the plug, you will be able to smell the burnt trans fluid on the plug electrode if in fact that's what's going on.   I may be all wet here...(ya pun intended ) 
 It only takes a few minutes, won't cost much and the smell of burnt trans oil is easily distinguished.
  Tuck\o/

[Foxx4Beaver]

I wouldn't go any leaner on the pilot yet...unless you're fully prepared for a melt down/seizure.
Since you say you're still having problems, even after changing the pilot size several times, I myself would do a leak down test...since you didn't say you have done one yet.
If it's got an air leak of any kind, it'll be impossible to get it jetted correctly, and to run correctly.
Good luck, and keep us posted.

[alward25]

What Tuck and Foxx said, if your crank seals, intake or base gaskets are sucking air, it will not idle.

[bandit88]

I was suspecting that, but the thing that had me stumped is that bad crank seals usually make it run lean, in my case its super rich.  Gonna start the tear down tonight. 

[Foxx4Beaver]

I was suspecting that, but the thing that had me stumped is that bad crank seals usually make it run lean, in my case its super rich.  Gonna start the tear down tonight.  

not if it's a clutch side crank seal....this is what Tuck was referring too in his post....it'll suck tranny fluid, which in return, will cause it to run rich.
If it were a magneto side seal...all it would have to suck, is air....and be critically lean.

[bandit88]

Thanks guys.  Just needed a little confirmation.  Just ordered bearings, seals, gaskets, case splitter, and some other stuff.  Pulling the motor tonight.  If I am ambitious it will be done by the weekend. Also tempted to order all new KIPS valves just to be sure everything is as good as it can be.  Those little drums are pricey though!

[Foxx4Beaver]

I wouldn't worry about the side valves too much...I would concentrate on getting new O-rings for the aluminum collars/guides for the valves, and get a new seal, new guide and O-ring for the governor rod(behind the little plastic KIPS cover on the right side).

[bandit88]

Thanks, just ordered that stuff as well!

[Friar-Tuck]

Hey, I need the number of your Sponsor!
          You won't regret rebuilding the old girl, and then you know how it's put together.  I can't tell you how many friends drop stuff off that "only had 10.hours" on them or were "Freshly Rebuilt" Oy-Va...
  Get yourself a service manual if you can, worth every penny..
Tuck\o/
   

[bandit88]

YAY, the sites back up!  So an update.  I tore into the motor, replaced all bearings and seals.  Cleaned KIPS, replaced the rod guide, the o rings and stuff like that.  Put in a new proX piston since the wiseco that was in it looked like garbage from just a couple hours. Anyway, fired the bike up and same issue.  In trying different things, I accidentally started the bike with the petcock off and after 30 seconds or so when the bowl started to run low the motor started running really good and sounds great.  This makes me think its carb problem.  So where im at now is 55 pilot, 165 main, needle second from top, 2 turns on screw, new needle valve, tired all combinations of float levels, carb is spotless.  I am not sure were to go at this point.  Anyone have any other ideas?

[Foxx4Beaver]

it could be the "needle seat" in the carb is worn....allowing it to dump excess fuel in.
Do you have another carb kicking around you can try?...even if you borrow one from a buddy, just to see if it makes a difference.

[bandit88]

it could be the "needle seat" in the carb is worn....allowing it to dump excess fuel in.
Do you have another carb kicking around you can try?...even if you borrow one from a buddy, just to see if it makes a difference.

I was thinking that but I didnt see that as a replaceable part in the Kehin or Kawi parts diagrams.  I do not have another carb.  Anyone know if the seat is replaceable?