spark plugs query
 

a friend is looking at a KLR 600, its a little tatty but sound, however on a run the plugs need re-gaping after about 400 miles !! I seem to remember hearing something like this before.I've tried the search function but I can't seem to get it to work.
Can anybody help me as to why this is happens. Thanks:thumbup1:

Maybe it's simply running lean? Lean condition creates high temperature and a lot of reactive oxygen, that can interact with hot metal parts like exhaust valve seats and spark plug.

I would check the carbs (maybe the jets are clogged?) and valve lash- it could be severely decreased in this situation.