KX Riders

Maintenance & Technical => KX500 Original => Topic started by: bkruse on July 11, 2005, 06:20:39 AM

Title: jetting of kx500
Post by: bkruse on July 11, 2005, 06:20:39 AM

I recently purchased a kx 500 from reno nevada. I am on the east coast and the bike hardly runs. I took the carb off and changed the main jet to a 162 but the book calls for a 175..and the slow jet is a 68 and it calls for a 62...Now my question is "do the ship kx from the factory with diff specs for diff parts of the country or are they the same, and customers rejet the bikes? and also what is the best jet combo for delaware/jersey/pa area???

Title: jetting of kx500
Post by: alan on July 11, 2005, 06:57:22 AM

I think most of them are set up for sea level when they are new! I run 168 main and 56 pilot at 4000'

Also check the above sticky on jeting!

Alan :)

Title: jetting of kx500
Post by: Minnetonka_Mark on July 18, 2005, 11:05:11 AM

bkruse,
One thing you need to know about the KX500 is that you will never be able to eliminate the engine surge.  By "surge" I mean when you close the throttle the engine speeds up and slows down a few times until finally settling into an idle.  Some people have tried to reduce this via jetting changes.  I think the majority here believe that this is natural to the KX500 engine.  Some also believe that this indicates that your jetting is close to ideal.  I feel that my jet setup is correct and my engine surges.

My bike is a 2002.  Everything is essentially stock (pipe, reeds, etc...) except for the jetting.

Stock 2002 KX500 Carb Setup:
Main - 168
Pilot - 58
Needle - N82M - 3rd from top (i.e. middle)
Slide - 7

My bike ran horribly with the stock jetting!!!!!  Especially poor from idle to half throttle.

My changes from stock for 1000 FT:
Main - 170
Pilot - 52
Air Screw 2.5 turns out

At 2.5 turns out the air screw just barely affects the idle.  This would indicate that the pilot jet is still too large.  However, I will not go any smaller.  The bike needs fuel flow for lubrication when the throttle is closed.  I want to stay on the slightly rich side.  My throttle response from idle is excellent.  I've never needed to think about carrying a spare spark plug.  It starts on the first or second good kick and once completely warmed up it runs fantastic.