Re: Small Engines cold air and Performace.
If its a shrouded engine you could try blocking off part of the fan inlet to regulate the temperature but it would need to be blocked off inns way that the fan cant sucknin whatever your blocking it off with, and you'll need a way to monitor the temperature so you can block off the right amount, it can still overheat if totally blocked off or too muchnof the inlet is blocked. If it has a screen toncover the inlet duct tape works good for this. Try blocking off about 1/4 of the inlet and see if anything improves, but also remember it could be running lean, which could lead to detonation by the time you get it to operating temperature so it may not be worth messing with, just pay attention to what your engine is acting like if you try any of this.
I'm sure you've seen some cars and especially big trucks or 18 wheeler's driving around with part of their grille's blocked off when its really cold outside.... pretty much the same idea.