Detonation on deceleration
 

Is about ktm exc 250 2011

Jetting: 38p n8rw@3 168 main jet. ( even with 172 or 175 will make same pimping in deceleration from with)

Temp 5C elv 500m

With n8rj and 38 168 is ok but too soft on bottom end.

So after riding 100000 topics about this problem I find this: too rich on pilot! Is strange but il logic think.

With leaner needle I don't have detonation,so that is.
I really want to use W needle. I have 250 and I want more power/snap from bottom.

Fuel knock on decel seems common on the ktm. Leaner pilot or slide may help, before you get too lost in the jetting try your original setting using higher octane/race fuel for a more controlled burn.

I've found the best way to reduce fuel knock on decal is by lowering the slide as much as you can. Often if you are willing to sacrifice the idle speed a bit it'll make running much cleaner.

Lowering the slide/idle speed helped mine the most even after messing with jetting, needles and slides.

Yes, that is the solution. The good one. I don't have race fuel in our country. The lower number of octane is 95 but I use 99 always.

I have NECJ needle too. But I feel it too soft right from the bottom.

Jakob I use your knowledge even with orange machine ��

Update: 42,40,38 pilot jets whit NECJ@3 165 ( with 38 n3cw #3 the same),will make tha same thing: detonation.

So, if with necj and w needles will detonate on decel those needle shave something in comun: rich from bottom.

I have N8RW N8RJ N8RG N3CJ N3CW M2ZJ witch one to use for best bottom end?