The self-propelled GXV140 engine uses the cast iron camshaft from the self-propelled GXV120 engine, so you've dodged the only weakness I can think of in the GXV140 engine (the plastic camshaft). 21" self-propelled Hondas are very heavy machines, and mainly for that reason I don't like them. The first time you lift it up onto the bench you'll understand why.

While I have said that the GXV140 has no weaknesses except for the plastic camshaft, to be fair I have to say that it is the only Honda engine I know of, with a tin-pot starter. The GXV120s is robust and reliable, while the GXV160s is bulletproof, but the quest for light weight on the GXV140 led them astray I'm afraid. The starter on mine was too beaten up to use when I got the mower. It was repairable: a metal disk glued to the plastic pulley, which was split; a bolt through the center to substitute for the sort of glorified giant roll-pin which had been the main shaft until somebody got at it with a cold chisel and mallee-root, a new cord, and some TLC here and there to keep it from eating its cord, and it was a usable starter.

Replacement starters for GXV140s are available on ebay - here is an example that at least shows you what they look like:
http://www.ebay.com.au/itm/LAWN-MOW...mowerAccessories&hash=item27d3c41b77

Be careful of advertisements that show pictures of GXV160 starters and say they fit both GXV140 and GXV160: as far as I know, that is wrong.