18 hp Evinrude,twist grip throttle setting

In have an Evinrude 18hp outboard,I bought it about 2yrs ago.It fired up for about 20 seconds on the day I bought it,the petrol in the tank was very low,but it fired up without removing the plugs and squirting in some juice.
I have just got round to having a look at it.
The throttle twistgrip is well out of calibration,about a third of a revolution.
I suppose if I take it apart I will be able to figure it out.
I was wondering if there is a procedure to follow to re-set it?
I haven't managed to start it as of yet,it has a spark on both plugs,and the glass fuel bowl is full.I have set the slow running needle on the carb to one and a half turns out from fully turned in.The choke is fully operational.
It's a very tidy looking motor,and only ever been used in freshwater.(The RiverTrent)
Any idea's will be gratefully appreciated.
"V"

 

The 1st procedure is dowoad the manual then follow the procedures.

 

The marks rarely line up on the twist grip, and it really doesn't make much of a difference.

On some you can make small adjustments, on others you can't, most people just leave it as is.

 

Many times it's not an out of calibration issue, but simply the glue not holding the rubber grip, onto the aluminum tube (or plastic) it's bonded to. If the throttle operates normally, this is likely the case, but if you can't get her to crank the throttle arm to its stop, then you have an issue. So, check to see if the throttle arm on the carb linkage, is touching the stop at WOT position. If it is, it's just a slipped grip rubber, if not, you have more investigating to do.