On the topic of replacing cam chains in the V4 motor,
my local V4 specialist mechanic says...

The simplest approach for changing cam chains is to pull the motor.
Well, it's not simple to remove the motor, but once the motor
is out, it's simpler to work on.

It can be done in frame but it's risky:  it's harder to get at
and if you make a mistake or drop something inside it's a lot
harder to recover than if the motor is free on the bench.
Also all four cams must be timed at once which involves
lots of timing checks and crank turnover,  which is easier
on the bench.
If it were him doing it, though, he'd do it in frame to save
time and because he's experienced.

- remove all 4 cams after marking them all w.r.t. crank at TDC
- grind a chain link off (since original chain is endless loop)
- if using OEM Honda replacement chains, must tear down to the 
  crank because they're endless loop
- if using aftermarket chains, they're master link type so you 
  can leave the cylinders on
- in '86/'87 or so, DID changed their design, making the chains
  stronger and longer lasting, plus master link.  They work great.
  So go with DID aftermarket chains.  (Honda OEM's their chains
  from DID in the first place.)

- Oh, but in 1998/1999 I have received word from several people who
  could not get master link DID chain, and one person's research
  seems to conclude that it's discontinued.  Endless loop is all you can get.

- expect chains to last about 50 to 60 K kilometers