100% synthetic oil not when below 0o C?

[Leon_gasgas]

Hi!

My new '07 EC250 does not like full throtle in temperatures below freezing. The bike is crisp and nice until you try to give it full throtle quickly. It hesitates. If I close a bit the throtle, it revs out nicelly. Scared of the engine not getting enough petrol, I tried a 185 main jet after break in. Not good at all, rich everywhere... Went back to the 180 and emmediatelly was much better. I played as well with the air screw and things got even better. Currently at 2 turns out and tonight I am going to try 2,5 turns.

The manual says not to use 100% synthetic oil when it's cold. I used Mobil 1 and now Castrol TTS with no difference between the two. And of course here in Finland we use antifreezing liquid... Also, I get a lot of the black spooge out of the silencer.

Should I try a semi-synthetic oil following the manual, or keep trying setting the jetting right? I didn't have any similar problems with the '98 as long as I used the correct main jet. And always I used 100% syn oils.

Thank you for any replies!

Leon