Just a few clarifications for legacy readers:
You cannot service the filter on these pump assemblies. You can service the PRE pump filter, but not the post. You must either change the whole plastic housing, or find some way to un-melt the filter housing portion, change said filter, and re-melt together. If you figure out how to do that, please post it up! The pre-pump filter will help prevent damage/wear to the pump, however, the post pump filter is what will eventually cause reduced flow... which is how you end up with those expensive ash trays.
Fuel tank level has absolutely nothing to do with combustion temperature.
A completely stuck injector is a lot better than a slowly failing pump/drop in fuel pressure. If it's not getting any fuel it can't melt. :) But the #4/Right cylinder on these bikes (and the ZX14's, in my experience) will run hotter and give up the ghost before the others.... In my failures it has always run 4 -> 3 -> 2 for damage from worst to least. The insidious part is that it creeps up on you, slowly getting leaner over tens of thousands of miles. If you're in the habit of doing a lot of sustained WOT pulls or have questionable fuel quality, it wouldn't be a bad idea to to either test or replace the fuel pump assembly/system every couple years.... it's cheaper than one melted piston! AFR gauges are also great for catching this sort of thing before it gets catastrophic.
Pre-Ignition is a real bastard!
Thanks a lot!
I think I have the term wrong, I replied to the first post with the link to the servicing of the pump and strainer - which people around here call the 'teabag' or it could be the PRE one you're referring to
I noticed that cylinder 1 and 4 is a lot darker/burnt than 2/3 - again, I'm not technical with engines so it might be normal..
I'll just be replacing the 'teabag' every service, it's cheap enough and check-in the dyno every now and then to get the AFR...ideally I would like to get the AFR indicator installed so you know exactly what's happening.
Regarding the fuel level, the technician is very,very...very full of it so I believe this is just him, but he said mainly in hot weather (35 - 40 degree celc) the lower the fuel level the hotter the fuel gets, which contributes to hotter engine in general..so I guess it had somewhat of an effect, but it can't be that big to get a motor to pop
I've attached a pic of the pistons (4 was removed already) - so you can clearly se how black 1 is compared to the others...