pulse adernaline 125 photo guide to main jet swap

[superfamous]

Hi guys
I have a pulse adrenaline with a 150cc kit, stainless steel exhaust, custom air filter, with the vm22 mikuni carb.
Now I have a #100 main jet with a #20 pilot jet. The bike runs fine, however when I hit the 7k the bike starts to fail. If I push hard the acelerator the bike goes fine and start to gain revs. it seems that it only fails in a specific acelerator position...
What do you think about my Spark plug?is the mix ok?

plug1.jpgplug2.jpg

thank you

[relentless addict]

its looking a bit black should be a chocolate brown colour is it moist(and smelling of petrol) or dry?? cant really tell from the pics

[superfamous]

its looking a bit black should be a chocolate brown colour is it moist(and smelling of petrol) or dry?? cant really tell from the pics

Thank you for your reply. yes, it is a bit black...so I guess that the mixture is rich. I only use the #100 main jet right now...maybe the pilot jet is too large (i'm using a #20)? because you are using a #115 and the mix is ok!
I think that I have a good air intake, so it shouldn't be a lack of air in the mixture.
My spark it's dry and don't smell too much of petrol.
cheers

[relentless addict]

if its dry and black your probs looking at a lean mixture rather than a rich one as you would be able to smell the petrol

[superfamous]

if its dry and black your probs looking at a lean mixture rather than a rich one as you would be able to smell the petrol

sorry about the questions. But the black colour doesn'i indicate a rich mix? I thought that a lean mixture should make the spark look brown and a rich mix should make it black.
I'll try a bigger main jet and see if it will work better!
thank you

[td_ref]

Lean mixture spark plug should look white. Main jet is most effectively at 3/4 to full throttle opening (which means does very little effect at small throttle opening).
Carb is complex, I found main jet at #100 is good for my 150cc. I recommend this reading (LINK) for further turning.