EC 300 2012 - jetting for singletrack (not racing)

[Jakobi]

FWW the N8RK is a full clip position richer than N3CK. K is one step leaner on the straight section than J. But.. As you've stated the KTM uses a smaller carb which pulls more fuel due to increased vacuum. But.. They are also very different engines from crank case volume, to porting, to exhaust flow so any comparison on paper is just that. Its the same with jetting your bike. I can tell you what works in mine, but it might not work in yours. Depending on where we are in the world our fuels throw some pretty big variance into the picture, along with the other normal variables. I also haven't touched a 2012 model so don't know what they are asking for in terms of fuelling/carby.

What I did though, is give you a baseline that has worked for many others in the past and a battle plan on how to get things happening. Its a methodical process. To complicate things though these bikes are hard to get the pilot circuit dialled in with the air screw making a difference. A quick search on that and your mind will boggle. Basically, they run a large squish clearance from the factory to accomodate all the countries they ship to so best bet is to tune the off idle response by feel. If you go too far the idle will hang and the bike will hesitate when cracking the throttle quickly.