Bike running lean, can't seem to get it right

I cant seem to get the fuel/air mixture right on my 1981 kz750h2 ltd after having replaced a bad engine with a good one with lower miles. The old engine ran amazing with 125 main jets. Apparently the new engine i have put in was kitted/bored out to 810cc. I didnt really beleive the guy when he told me this because from the outside it doesn;t look like the engine has ever been apart. But now Im up to 138 main jets in the carbs and even turned the air screw all the way down and the bike is still running lean...so either this engine really has been made into an 810cc or i have some phantom problem else where.

Any one have any experience jetting a bored out kz motor? Is there any other adjustments that can be made to balance out the fuel air mixture? Is it possible my carbs cant handle the increase in cc? Im still not completely sure the engine is an 810cc but it seems to be based on my increase in jet sizes

the engine is very tight and i get 180psi in each cylinder. its not pulling excess air from anywhere that i can find

Have you raised your needle? Roy

I have not raised the needle...how much do you suggest?

At least one slot. I generally clip mine on the third slot from the top. Roy

so i raised the needle up a position and it helped a little but still lean. Should i keep raising it? Or should i go bigger with the main jet (id be up to a 140-145 size) and then raise the needle again if it still needs? i havnt messed with the pilot jets at all and the float height and fuel bowl level is the same as it was with the other engine.

Thanks alot,
B