Where is the coolant drain on the 1985 maxim x motor

Are you wanting the size of the hex bolt head or the thread size and bolt length? Most oil pan plug bolts are either 17mm (5/8th socket) or 19mm (3/4" socket) bolt heads.

If you want to know if your motor is locked up. Hand shift the bike into third or fourth gear and see if you can turn it over by spinning the rear wheel by hand or rocking the bike forward and backward. If the starter motor is spinning but the motor is not , and the motor is not frozen, then you have a bad one way clutch and starter gear in side the motor. http://www.bikebandit.com/houseofmotorcycles/1985-yamaha-xj700xnc-maxim-x/o/m10113#sch514113

at the bottom of engine should be in between exhaust

Actually, they're not Hitachi carbs. Since you have a 1985 "Maxim-X", the model number is actually XJ700XN. The XJ700 does indeed have Hitachi carbs but your bike, the XJ700XN Maxim-X has BS33 Mikuni carbs.

Careful with the model number, the XJ700 and the XJ700X are entirely different bikes.

By the way, if you want more answers about your Maxim-X, feel free to visit the "Maximum Maxim-X" web site at www.maxim-x.com and the lesser known FTP site for the Maximum Maxim-X web site at www.maxim-x.com/pix

HAP

Try www.bikebandit.com/
Or go to yamaha for the OEM parts.

First you want to disconnect the positive cable to the starter, than unscrew the 2 bolts holding the starter to the motor, pull them up as far as you can and you will be able to pull the starter out.

It seems the float chamber of the carbs are not getting enough fuel (gas).
Try to check this first by opening the carburator float chamber drain screws....thn select the petcock to 'prime' positon and see if theres fuel running out of those drain screws freely.If not thn it time to clean the carbs.
Not bad too to remove the spark plugs and clean them and regap.
Hope this helps!