What would cause a suzuki 600 to die when you put it in gear?

I am assuming you mean the Suzuki GSXR600 motorcycle. ANY motorcycle whose engine dies when you engage first gear MOST PROBABLY has a CLUTCH problem. Have the clutch tightened. To check whether the clutch is CLEARING the gear, do the following:

1. With the engine turned off, hold the clutch and put the motorcycle in first gear.

2. While holding the clutch, push the motorbike forward. If the rear tire allows the motorcycle to move forward, the clutch is engaging properly and clearing the gear.

If the motorcycle won't budge with the clutch engaged, the clutch is not engaging properly.

If the clutch has been tightened and is too hard to engage, you might want to have a mechanic open the motorcycle and check the clutch discs- they might be worn out.