My beta Evo seems to idle well about 3.25 turns out on the air screw. I'm convinced it's idling rich. I seem to be turning the idle screw in so much to maintain idle I think I'm bypassing the idle circuit. I'm considering a smaller pilot jet. It currently has the standard 55 pilot jet 130 main jet and middle clip on needle. Mid and top end power is perfect so I don't want to fiddle with that end.

I don't want to buy a pilot jet assortment kit but instead would just like to buy one original keihin pilot jet. I'm just wondering what size should I buy ? It seems keihin sell 52, 50, 48 and further down. How much of a difference would 52 make compared to my current 55 or will I need to get lower than a 52. Any suggestions welcomed.

Good evening Gazza. My 2019 250 Evo came with ( and still has ) a 48 pilot jet. I haven't come across anything as high as that in my previous Evo's. A 55 would make it rather rich.

Mixture / air screw or whatever you want to call it is usually about 1 3/4 turns out. 

For peace of mind, check with lampkins.

 

You show you have a 2019 250 Evo but the owner's manual for that model lists a 48 pilot jet and a 125 main whilst it shows a 55 pilot and 130 main for the 125 model. 

Not answering your question directly but it appears your carb is jetted incorrectly for a 250, if indeed that is the bike you have.

11 hours ago, peter_steer said:

Good evening Gazza. My 2019 250 Evo came with ( and still has ) a 48 pilot jet. I haven't come across anything as high as that in my previous Evo's. A 55 would make it rather rich.

Mixture / air screw or whatever you want to call it is usually about 1 3/4 turns out. 

For peace of mind, check with lampkins.

 

Hi there. Yes I spoke to lampkins on Thursday and they confirmed the 55 and 130 were standard jets for my 125. My needle was on the 4rth clip down and they said to put it middle. Top end and middle run perfectly with needle in middle and 130 main jet. It just seems to not idle well at low revs unless I increase the tick over. Lampkins also recommended a bp5es plug instead of the Br7es and said to set air screw at 2.5 out.

I think I may drop a size in the pilot jet and see how it performs.