YES, I found the Keihin maybe model08 versus 03 different diameters. Those may not be the actual numbers but they are certainly different plunger diameters. Probably all Honda's attempt on the 85 250SX cold start issue...... One may be an 05 Keihin but I know that the good starting carb is the Keihin 08...............
I'm sorry I forget the actual numbers........
a 350X carbs wth SX jets, the A?B lid off and an exhaust help her giddy-up and go 
Don't be scared to propane torch that puppy, the aluminum won't melt at that temp.......
All our government does is distract us while they steal from us, misspend our tax $ and ruin our country