Jetting What is jetting? How does it work?

air filter dirty can cause it to run rich. Should be cleaned every 10 hours of riding.
Mix should be at 40:1 in winter and 36:1 in summer. Use a ratio right dont guess on the mix.

Finally - get a JD jetting kit and install it! Crucial for all ktm bikes.

Curious what jetting are you currently running>

Hey Anon,
Proper and correct jetting is something that can only be achieved in person by a REAL MECHANIC that KNOWS how to "read" a spark plug,,,With the mods you mentioned.. you need to know the stock jet sizes..a close guess would be reduce the main jet by two or three steps and lower the needle one clip position... oil mix should be at least 32:1....or better yet 28:1.. KEEP the oil mixture and jet the carb for performance....( I see TOO MANY IDIOTS that instead of jetting a carb correctly just reduce the oil ..some as low as 50:1(INSANE) just to keep from fouling plugs.).. then WONDER why their engine doesn't last long... hahaha????
YOU > BE SMART!!

Thanks for contacting FixYa with your KTM inquiry.
50 kilometers is equivalent to 31 miles. The tank capacity is 2.9 Gallons indicating you are obtaining a very sub-marginal 10mpg approximately.
A couple things to check would be:

• Leaks/cracks in the fuel line.
• Access fuel is going somewhere - is it making OIL/Going out the pipe? Seals or Jets!
• Excessive smoke out the pipe.
• Pipe color coming out of the cylinder head (Cherry Red = over fueling)
• Spark plug color - should be a nice cocoa brown is jetting is correct.

More than likely you have either a stuck float or a jetting problem. Both are very easy to fix. Tap the float bowl with a back side of a screw driver and see if it frees up. Test ride!
For jetting, you can raise the clip on the needle a couple of notches so the needle lowers and this should help conserve fuel in the middle RPM range.
The pilot jet and tower will gobble up fuel like crazy at low RPM's if they are to large a diameter. Refer to your manual and check the stock size for jetting and start with that. Elevation and temp has some effect on jetting as well. Just sounds like more than likely your needle and pilot jet are over fueling the engine.
Hope this gives you a few ideas. Let us know if we can be of further service,
Kind regards,
TF

Hi, It seem you have problem with secondary fuel jetting that giving you lean AFR during acceleration . Please check your jetting and has it cleaned and working well. Regards

The amount of unspent oil you see dripping from the end of your silencer is lovingly called spooge and it is a sign of a rich fuel condition. The common way to solve this by a jetting procedure. Your manual may be able to explain this, and the different jetting parts that are available, but be careful of errors in your manual. I've spotted at least 2 important ones in my 03 manual! Basically you need to replace/match jets for your particular conditions. Winter riding will be much different than summer for example. And Denver will be much different than somewhere at sea level. Find a jetting procedure for 2 strokes and test different pilot jets, needle jets, and main jets at your track until little to no spooge is seen. Be careful, of course, to also check your spark plug for a cappuccino colored tip to make sure you haven't jetted your carb too "lean". Finally, make sure to run 30:1 fuel mixture consistently through jetting (or 32:1, whatever your oil and bike manufacturer recommend).

Well, now that you asked, by removing the baffles it changes the back pressure on the exhaust system. In some cases this causes need for re-jetting the carbs to make it run a bit richer. There are a lot of riders out there that like the louder sound of the baffles either drilled or removed entirely. The exhausts are factory tuned to match the jetting of the carbs.
Keep an eye on the exhaust pipes to see if they start turning blue. If so, it is a sign of the engine starving for fuel and would be a good time to consider re-jetting. Or, if you like the color blue and purple on your exhausts you can leave the jetting alone.
Ride safely, Ed

the jetting/ jets are fittings inside of the carburators that allow onlky a certian amount of fuel to burn so the motorcycle does not flood itself out by having to much or to little fuel

main jet = #165

slow jet = #42

WHAT MEAN JET? : Carb jetting can be easily understood if we understand the basic principles of carb and engine operation. A carb mixes fuel with air before it goes into the engine. When the mixture is correct the engine runs well. The bottom line is a carb must be adjusted to deliver fuel and air to the engine at a precise ratio. This precise ratio can be affected by a number of outside and inside influences. If you are aware of these influences you can re-jet your carb to compensate for the changes. I'm going to show you some examples of how you can change your jetting for better performance and in some cases increased engine life. As with any engine work be sure you have good tools the correct parts and a good manual before you get your hands dirty! ALTITUDE COMPENSATION: For our first example let's say we find a new riding area WAAY up in the mountains. Our jetting is dialled in for our usual riding area which ranges from sea level to 1500 feet. Our NEW riding area starts at 4000 feet and goes up from there. Going to a higher elevation will require will require a jetting change but which way? Like our fuel density air density can also change. Higher elevations have less air density then lower ones. At high elevations our engines are getting less air so they need less fuel to maintain the proper air/fuel ratio. Generally you would go down 1 main jet size for every 1750 to 2000 feet of elevation you go up (info for Mikuni carbs). If you normally run a 260 main jet at sea level you would drop down to a 240 at 4000 feet. Something else goes down as you go up in elevation is horsepower. You can figure on losing about 3% or your power for every 1000 feet you go up. At 4000 feet your power will be down about 12%-even though you rejetted! For our second example let's say we are still at our new 4000-feet elevation riding area and a storm comes in. We head back to camp and ride it out overnight. The next day there's a foot of snow on the ground the skies are clear and it's COLD!. Aside from getting the campfire going and making some coffee you should be thinking about jetting again! Cold air is dense air and dense air requires bigger jets. If the 240 jet ran good the day before you will need a bigger jet to run properly today. If the temperature is 50 degrees colder,,