"Take the left fork to wrap around behind Y Mountain and reach the summit from the east."
Although, I technically agree with your words above, I think it would be worth mentioning that the east going bit of the hike is only perhaps a hundred yards. Essentially the mountain is climbed by ascending the valley to the south of the Y (named Slide Canyon) which you mention. Just as the trail basically plateaus in the south valley it veers left (north) and within maybe 20-30 yards it curves to the east (in a leftward direction). As you go east you very soon reach the top of Y Mountain.
The trail never really warps around the back of the mountain as it climbs the valley, it's just that the last few yards to the peak have you walking to the west.
If I had to guess, I'd say the hike is about 3.5 to 4 miles each way, and since it climbs 3,300 ft the time for a round trip will be about 4 to 5 hours.
Thanks vanman. The distance and elevation gain sound right on. I included the changes on the main page.
From the article: "They will point left (south) into the bottom of the shallow drainage that cleaves the mountain into east/west hemispheres."
You're sending people up the wrong mountain with that parenthetical statement... :-)
Good catch. I just changed it.