Until Japan started their expansion in China proper they got along with the US mostly just fine. Outside some sternly worded letters, the US never seemed to care overmuch about Japanese expansion until they turned China into their personal quagmire. Relations soured when the US tried to force Japanese withdraw from China with economic sanctions. If Japan stays out of China after WWI (or approaches the situation differently) then they'd be a strong ally for the US against communism further into the century, which the Japanese government in the 20's and 30's hated with a McCarthy-esque passion. Much of Japan's expansion in China was domestically portrayed as a fight against communism.
As a relevant note, Japan and Britain got along great with Britain actually training much of the early Japanese navy's officer class. And don't forget that Japan was on the Entente's side in WWI.
I doubt the US would directly ally with Japan before the 1920s or 30s at the very earliest. In this period the US is still wildly isolationist and mostly didn't care about balances of power and even a friendly Japan would still have politics that were unpopular in the US. Also, now that I think about it I'm not sure that the US was allies with anybody before WWI.
I think a US-Imperial Japan alliance aimed at containing communism, China, and Russia in East Asia is perfectly reasonable a little later in the century if Japan can keep themselves from making a mess of China, forcing the US to act and impose sanctions.