jetting tips

[kdx357]

i just modified the pipe on my 89kdx 200 last night i was wondering about the new jets to put in, the tech tips at justkdx.dirtrider.net suggest leaning the jets , they say to put a 152 main (155 is stock) 45 pilot (48 is stock) and a 1173 needle (1172 is stock) any way to get to the point all i can say is my bike is currently running lean should i buy lean or rich jets , the reason i asked this here is i couldent get a answer in the kdx forum.

 

[skhasky]

If you are running lean you want larger (richer) jets. Pipe mods don't usually effect jetting much - so, slight changes should get you going!

 

[kdxtaz]

I've read a few of your posts stating that your jetting is lean. Get this resolved now! Not enough fuel in the mix = not enough oil. You'll burn it up. The tech tips on the KDX site are highly accurate. Follow directions for plug chops at various throttle positions. The bikes are jetted too rich stock, so if you're too lean with a 155 main on an otherwise stock carb, then you should take a serious look for air leaks at the carb base/reedblock area.

 

[kdx357]

its definantly running lean, and i dont think theres a air leak, i dont know how lean because im no pro at jetting this is my first time. would lowering the clip position help?

 

[kdxtaz]

When jetting you should start with the main circuit with plug chop at WOT. When that's right, then do plug chop at half throttle to check clip position. Always start rich, then work towards lean, as rich will not hurt the engine, only performance. You should maybe start with a 160 main. If still to lean, go higher. Make sure you do plug chops correctly, closely following instructions on KDX site. Plug should look med. brown on insulator bottom (down inside). Do not run the bike lean, as it WILL cause damage. Every second counts! Hope this helps & good luck. P.S.- Make sure the fuel level (float height) is correct, as low level will cause lean condition. :D

 

[kdx357]

i dont really know how to check the float level but i have gorrs book , i pulled out the jets awhile ago i have a 158 main, 1172n needle, and i dont have the right screwdriver to get the pilot out . it could be the float level that would explain a bit.

 

[kdxtaz]

In JUSTKDX tech tips under "engine", there is a page just for float level. Find it and carefully follow instructions. Did you have this problem before the pipe mod? I've never known anyone that ripped the guts out of their stock pipe, so I don't know how this would affect jetting, other than undoubtedly making it leaner.