Opinion: Timing chain replacement on a motorbike?

Question

The intake sprocket on my bike is being replaced because it cracked. I'm looking for opinions as to whether I should also replace the exhaust sprocket and timing chain, or just the intake sprocket. Without the sprockets in place I can't currently check for chain wear. The exhaust sprocket appears to be fine. (DOHC of course, KZ750-N [Spectre])

Answer 1

you should replace everything

Answer 2

mileage  would be the judgement factor to consider if it is a low miles bike then just replace the cracked gear  if it's mileage is getting up there replace all the gears and the chain as well as the guides and tensioner !         it can also be a matter of how hard the bike has been ridden I once bought a gs 1100 with only a bit over 20 k miles on it  but  the timing chain setup  was already shot  due to it belonging to a ricky racer  lol

Answer 3

A shop manual should give you a pin to pin measurement to determine if the cam chain is worn.  Chains don't stretch, they wear at the pins and rollers (if a roller type chain) and thus get longer.  A few links of your chain could have truely been stretched if the chain was kinked and twisted when everything shot craps.  

First you need to determine if you have a roller chain or link plate (Morse) because the later model Kawasakis used the latter.  Find out what the wear limit is (I can probably tell you if I know they chain type) and measure the chain.  To measuer the chain, all you have to do is apply tension and measure pin to pin.  It doesn't have to be mounted on the cam sprockets.  If it's ok, then inspect the entire chain to make sure it hasn't been kinked sideways.  

As far as the sprockets go, I suspect it was the intake valve(s) that brought everything to a screeching halt.  If none of the exhaust valves were bent, then most likely the exhaust sprocket is ok.  It wouldn't hurt to give it a close visual inspection though.