First off, I'm not particularly knowledgeable about WWI-era geopolitics, so bear with me if I say something that's ASB.
Trotsky is luckier. tries out exporting socialism. Causes shitstorm. UK/France fight against him. Germany remains neutral as the population wont support fighting for the French of British.
(Interesting fact, "Weimar Germany" was officially called the German empire or Deutsches Reich.)
I dunno much about Marxism and Russian affairs, but (from what I can gather) your scenario is to make Russia go the revolutionary route and have Britain and France fight it. Wouldn't Germany also get involved from the get-go, given that she shares her border with a potential powderkeg? Also, who's to say Trotsky
won't export revolution to the Reich?
Besdies that, didn't realize Weimar Germany was officially called that way!
Russo-Japanese war is avoided, and Russia focuses on the Balkans. When the Harden-Eulenburg affair turns into a scandal, Wilhelm II suffers a nervous breakdown on the eve of Bosnian annexation.
Russia opposes the Austro-Hungarian annexation plans, and mobilizes on Austrian border. Bulgaria utilizes the crisis to declare full sovereignty, and after botched negotiations, the Ottoman Empire invades Bulgaria in an attempt to retain her control of Macedonia.
Russia uses this as a pretext to go to war against the Ottomans, while Italy follows suit by invading Libya. Britain and France are att odds on how to proceed, while Austria-Hungary declares the annexation of Bosnia-Herzegovina anyhow.
German elites are divided on the best course of action, and with the Emperor virtually incapacitated, the military readiness is increased, but Germany still refrains from declaring war against Russia.
Okay, didn't realize Germany had such a scandal! Interesting!
Basically, this is the Bosnian Crisis gone horribly beyond control. I can see the Big Three Powers vacillating for a while before throwing their lot in with either side. But I dunno if they would stay on the sidelines for up to two years, especially given the geopolitical consequences. But then again, The Big Three may throw in their lot with the status quo and join in as their own side to restore order (though I admit that's waaaaay unlikely).
During the Ottoman-Italian war Conrad get his desire to start a punitive action against Italy...that end well like the first invasion of Serbia in OTL 1914 so know Italy and A-H are in a state of war...Germany decide to not get involved due to being allied with both and because Wien acted even against Berlin wish.
The Hapsburg action cause a cascade reaction in the Balkan and the League is formed not only earlier but also to fight A-H (and the Ottoman)...and Russia is bringed into the war somewhat later to support the league and with her come also France (but for the moment even if had declared war to the A-H and OE it limit her involvement on the naval and logistic side due to the need to keep an eye to Germany and the UK)
So basically, make it a 'staggered war' based on the hostility of two Powers whom are both allied to a third Power (Imperial Germany). Interesting... and the fact that France limits herself to just her navy and logistics in order
not to piss off London and Berlin opens lots of butterflies!! I can see the latter capitals taking a harder stance as the war goes on, though still going the will-we-or-won't-we motions.... until something war-changing pops up.
In all, it seems the best way(s) for Imperial Germany to become neutral is to either:
1. Paralyse the upper reaches of government (i.e. the emperor and/or his ministers)
and/or...
2. make it divided between competing alliances and loyalties.
and/or...
3. Make her neighbors get involved, but only on the naval and/or logistical side so as to not piss off Berlin.
Would it be possible to combine some of the above points? It just seems too good not to.
EDIT:
This happened in Fight and Be Right.
Oh, really? Need to look that one up!