Depends on what you mean by "win". It also depends if Japan has allies and who these allies are. I could certainly imagine a PoD sometime "after 1700" which could place Japan in an alliance with the British Empire against the USA. In this situation, even if you don't weaken the USA, Japan could win such a war and end up with huge chunks of the former USA.
But, I assume you are talking about a one-on-one conflict, not a war of alliances. Since we are not allowed to weaken the USA, we must create a far stronger Japan. So here is a rough and ready time line:
1700-1750 Japan unifies earlier and abandons its isolation. The island is "opened" by the British, who then lose interest, seeing greater opportunity for money in China and India
1750-1900 Japan, alarmed by initial British contact, begins to adopt western technologies and institutions in the same manner as OTL 1870-1900. By 1830, Japan has entered into treaties with Britain giving them access to naval and military technologies. By 1860, Japan (having joined the British and French in the Crimean War) has invaded and anexed parts of the Russian far east. In 1870, Korea is annexed, and in the brief Japanese-Spanish War of 1890, Japan siezes the Phillipines and Guam. In 1900, the Second Russo-Japanese war confirms Japanese control of much of the former Russian pacific coast.
1900-1941 By 1900, the Japanese Empire is one of the major military powers - and is recognized as such by the west. War breaks out with China in 1905 and Japan siezes all of Manchuria. Over the next 5 years, the central Chinese government collapses, leading to defacto partition of the remainder of China between Britain, France, Japan, and Germany. (It is during this period US attitudes toward Japan harden). In 1914, there is a war equivalent to OTL WW1, and Japan joins the Entente, seizing Germany's Chinese protectorates and pacific holdings. By 1935, Japan is a major continental power, fully exploiting its Chinese and asian colonies. It has the second largest Navy in the world, a huge industrial base in Manchuria, Korea, and parts of Siberia, and a massive army made larger with millions of colonial auxilliaries. The nation is fully modern and has an industrial output equivalent to OTL's Soviet Union (which is butterflied away in this TL by an earler collapse of Russia as a major power)
1941-1947 - Rising tensions with the USA lead to the Pacific War (which only involves these two powers although there is a 2nd European war going on at roughly the same time). IN this TL, Japan does not strike at Pearl Harbor in a "sneak attack", but rather declares war in large part over the treatment of Japanese imigrants in the US and Hawaii (as a virtual industrial and military equal to the USA, Japan does not feel the need to adopt the sort of "strike first and defend later" strategy it adopted OTL). The Japanese defeat a major portion of the US fleet defending Hawaii and quickly occupy the islands. This is followed by an island hopping campaign in the Aleutians eventually leading to landings in the Alaskan mainland (Alaska is still american in this TL). In 1943, "front lines" have basically stabilized with Japan in control of Hawaii and a significant portion of Alaska (in this TL Britain and Canada are neutral and the US lacks any means of resupplying Alaska overland. There are many naval battles associated with the Alaska campaign and Japanese carrier divisions regularly mount raids on US west coast bases and cities. The US regularly retaliates with a long range bombing campaign against Japanese facilities in Hawaii and carrier-based hit-and runs closer to the Home Islands.
The deciding year is 1946.The US Pacific fleet has completely recovered from its losses in 1941 and has been reinforced with much of the Atlantic fleet. Japan has also built its forces up. A major US campaign against Hawaii is intiated, with diversionary landings in the Alaska. In "the largest Naval Battle in History", the Japanese Navy is victorious in the Battle of Hawaii. Losses on both sides are heavy, but the US suffers more and Japan retains the islands, and is able to reinforce its fleet at Hawaii, maintaining overall naval dominance in the eastern Pacific. The US beachheads in Alaska are successfully maintained, but long-term success for the Alaska offensive is considered unlikely. Japan begins planning for an invasion of the US west coast, which is something that many Japanese believe would be difficult to acheive, even with the US in a weakened state. The new administration of President Wendell Wilkie is shaken and public support for the war is dropping. The US is looking for a way to end the war.
1947 - Separately, both the US and Japan approach Britain to help negotiate an end to the Pacific War. Against a background of continuing military activity, negotiations begin in London and bog down. Then on October 1, 1947, the Japanese deploy a "uranium bomb" against the US Beachhead near Nome, Alaska. The US forces are completely eliminated and the dynamics of the London negotiates radically change. With the threat of this weapon being used against its Pacific Coast cities, the US agrees to a final settlement which gives Japan all of Alaska and creates an and independent Hawaiian Kingdom. The treaty requires fair treatment of "Americans" in Hawaii and "Japanese" in the USA.