today i just got my engine running in my hotstick 40, its a 46 super tiger, basically its great until i angle it up, and it wolnt increase throttle, but i leaned the low end and now it is perfect, but my question is, why does leaning the low end makeit so that it will rev up when its vertical? it makes no sence

My guess is that your High Speed Needle valve is too lean!

My thoughts as well. The low end needle really shouldn't have much effect, if any, on the high end throttle. Strange. If you're throttling up from mid range to go vertical and the low end was rich enough to keep the engine from winding up, then it should have been worse on level flight.

Tune your engine and then have someone hold the plane while you give it full throttle. Aim the nose up and see how it runs and then nose down and see how it runs. If it flutters it needs more tuning. Play with the high speed needle until it runs right in the two pitch attitudes I recommended! Should be fine then.

Gibbs

If your low-end mixture is fuel rich, you will have fuel accumulating in the cylinder at low speeds.
When you kick to full power (WOT), the engine will need time to burn all that extra fuel before it picks up, and it can even stop.

I believe the best is to always have a relatively lean mixture at idle, and then you set your high-end mixture to optimize your high rpm performance...

the supertiger carb is a bit different than other carbs.the two needle version has an interaction between the two needles.it is possible that the low speed needle is turned in too much so that the high speed needle can not richen the mixture.the sparay bar in the supetigre uses an elongated slot the low speed needle should not extend beyond the middle of the slot.usually to do a proper setup the loe speed needle is turned to the richest setting and then the high speed needle is set for max rpm with and backed off about 1/8 turn or so,then you lean out the low speed needle for a reliable idle a little at a time,the first few times you go idle expect the engine to die as it floods out,just close the low spped needle 1/2 turn at a time till it stays running so you can fine tune the low speed with the engine running,then recheck the high speed setting.

The low speed screw is not really needle (which is tapered). It is either a plug which enters the spraybar at low throttle or a sleeve which slides over the spray bar; this type has a slot in the bottom of the bar as earlier stated. If either is too close to the spraybar at WOT it will affect the HS mixture by not allowing the HS needle to control the mixture, in other words it fixes the mixture usually at too lean a setting. Hope this helps to answer your question. In other words the LS setting CAN affect the HS setting; it also affects your throttle setting up to 3/4 or so throttle as it slides out of the spraybar.

So far I haven't had any engines where the low speed adjustment mechanically interfered with the high speed needle. But I can see how that might happen on some engines where the manufacturer allows the low speed adjuster to move in too far.