Jetting!!! Again and again and again!

[SHLEPY]

Depends on the girth of the jet.

[sandblaster]

given....... I havnt read MOST of this thread.   but I havnt seen anyone discuss how premix viscosity affects jetting...  

Or lubricity.....

[motopunk]

i run at all my green 2 stroke monsters 40 : 1 mix (only motul)
 i tried in the first 32 : 1 and came more oil than smoke out of exhaust. (this rich mix i only use at new or complete rebuilded engines. 1 or 2 tank fillings than back to 40 : 1.)
some guys ride 50 : 1 . ktm says in manual book up to 60 : 1 for 250cc -380cc motors. maico and zabel (sidecar motors based on maico 500) says up to 100 : 1 mix for the 500cc - 700cc motors with their special oil ..

but i think i´m on the safe side with 40 : 1 mix. engine runs clear. piston look always like fresh installed, when i pull cylinder. 

its a simple rule: less oil in the mix = more effective power from the gas. but never take too lean mix or cheap bad oil, that will risking engine damage that one!!

[Friar-Tuck]

 
 
 
 Something like that,
 When you increase the mix ratio
(reduce the amount of oil mixed in the gas) this  makes the engine run richer.
 You will have "more" gas and "less" oil going through your carb at any given time.
Anytime the oil ratio is changed, the carb jetting should be adjusted.
  The same holds true when you decrease the mix ratio (increase the amount of oil mixed in the gas).
Increasing the amount the amount of oil will make your engine run leaner,  if you add too much oil you run the risk of engine damage if you don't re-jet the carb.
  Of course, you could adjust the mix to compensate for jetting issues.  Most guys adjust their jetting to the riding conditions.
  Tuck\o/     

 

[motopunk]

correctly...
 and I always say first take the right mix to ride in the tank, then you can start fine tuning and jetting. at least it is a good bike .. all my bikes start at 2 -3 kicks.
  with my KX500 was a really hard way to find the correct jetting. as i started the project I had only individual parts. I bought the engine with ignition and mikuni carb, but there were no jets, needle and slide in it. on ebay I found a keihin pwk 39, I drilled it up to 40mm. then at my kawasaki dealer I found in the spare parts lists which stock needle is used in the kx500E-models. then I had to do in 2 long weeks to find the correct pilot and main jet and needle clip position.

then I found kx riders.com and i saw i was exactly on the right way. I can only say it again and again, great web site 

[nirvanafan98]

Loved reading the Engine Chart and Carb tuning. Just learned a lot can't wait to try it out. Have 87 500 mods, Pro Circuit pipe a reed spacer and stock carb settings. Just rebuilt top end . Smokes to much, plug wet . Going to check timing then adjust air screw. Run 32 to 1 Bel -Ray. Maybe try 50 to 1 . Been using Bel- Ray since the eighties when  I races Moto in HighSchool . 

[deets]

Starting Point

You guys EVER gonna figure out the search function at the top of the forums?  

i searched for jetting chart but didn't get a spec sheet.  i guess i'm being stupid but i would like to see this jetting chart if someone could share a link to it or let me know where I can see it???

[sandblaster]

http://www.oem-cycle.com/KX500JETTINGGUIDE.shtml

http://www.oem-cycle.com/forum/viewtopic.php?f=5&t=109

[VMXSteve]

Hi Guys, I just picked up a mint 1985B1 KX500 with a Mikuni VM40SS Carb, and was looking for some basic / sea level jetting specs?

[motopunk]

Hi Guys, I just picked up a mint 1985B1 KX500 with a Mikuni VM40SS Carb, and was looking for some basic / sea level jetting specs?

which performance makes the bike?
 to lean? (white sparkplug) 
 to rich? (sparkplug looks always black and exhaust is wet with unburned oil)
 ideal is when the plug looks dark brown ... only other info i could give is on this website in the parts-shematics.

www.cmsnl.com
 oem-needles for the 85 are no more available. jets you could buy by any mikuni-shop for the mikuni-vm-carb

but never forget, if the bike performs well, dont change the jetting... 

[Foxx4Beaver]

Hi Guys, I just picked up a mint 1985B1 KX500 with a Mikuni VM40SS Carb, and was looking for some basic / sea level jetting specs?

Stock jetting on an 85 B1 is...

Main-380A
Needle-6DJ2
Jet Needle-R2
Pilot-40

...see if this is what you have, if so, run it...do a wide open throttle chop run and check your plug....chances are, it'll be a touch on the rich side, because Kawie ships them out from the factory setup on the richer side and at sea level.


Another thing to keep in mind is, these specs are for U.S. bikes.....so if you're outside the U.S., your stock jetting will more than likely be slightly different than what I listed.
   

[staffylad]

mine was sticking on when I first kicked it over but then a few minutes late it would settle down but no tunning ther so I stripped the kiehin and the jets wer in a bad way so im ponderin the idea of a jd carb kit lol they look great ibet the bike runs wicked with one of them in just the shippin is well expensive to uk 

[reklessj]

OK here we go again guys. 1994 kx500 TMR MOTOR, port, head and exhaust valve mod, .26mm head gasket, FMF  Fatty pipe  stock silencer. I'm at 3300 ft I recently had to change from running straight VP C-12 TO running 50/50 blend VP C-12 and 92 octane pump gas at 48:1 redline oil. Tom told me to run a 178 main,  60 pilot, needle 4th from top and air screw 1.5 out. It is running rich all throughout! Any input guys?

[sandblaster]

3300 ft and that jetting you should be spooging all over and having to clean out the top end by reving it frequently, or just deal with a blubbery bike.
I run 55/168 at 0-1000 ft and needle at the middle position.
I run 92 clear gas with motol 800 at 40:1
Both my k5's run clean and fast.

Look here for how to set up your jetting:
http://www.oem-cycle.com/forum/viewtopic.php?f=5&t=109

Follow the directions there, start with your pilot jet first, then move on.
I'm guessing that you will be running leaner then me but go slow, and follow the directions, and check your plug color frequently.

[reklessj]

When I was running straight VP WITH 60 pilot, 172 main, needle in middle, air screw 2&1/4 out. It ran tits and burned perfect should I go back with that setup maybe fatten up the air screw a lil