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Discussion Starter #1
Hi guys

I'm new to the forum but thought I'd add this.

I recently melted one of my pistons on my gen4, and basically a very long story short - it turns out the cause was a dirty fuel filter. This added load to the fuel pump which intern caused loads of crap with cylinder 4 (Cylinder 1 and 4 has different cooling routing so it's "hotter" than cylinder 2 and 3).

We have pretty poor quality fuel here in South Africa, but I just wanted to put it out there. Service that fuel filter every time you service you bike :grin2:
Also, I was told on hotter days, try not to go below half a tank of fuel since it adds to the core temperature of the combustion chamber..

The bike was a little lean at first, which I was aware of - after changing the filter and pump, not lean anymore...I'm sure a lot of you know this, but just in case.
I carried on and got the worst of it :headshake:

Pic attached of the piston...
 

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That sucks but wouldn't you see the same effects on cylinder one if it has similar cooling?

I just had my injectors flowed and found one of mine was stuck shut. Think you could've had a stuck injector on that cylinder too?

Edit: Also how do you service the fuel filter? I tried looking up the process in the service manual and it says The fuel filter is built into the fuel pump and can not be cleaned or checked."

I also saw when poking around the manual on how to test of the fuel pump is working properly or if the fuel filter is possibly clogged or a problem with the pump. I'm going to try this test once it warms up to be sure as it seems like a quick and easy test with no real special items nessecary.
 

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Welcome!

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!
 

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Edit: Also how do you service the fuel filter? I tried looking up the process in the service manual and it says The fuel filter is built into the fuel pump and can not be cleaned or checked."

I also saw when poking around the manual on how to test of the fuel pump is working properly or if the fuel filter is possibly clogged or a problem with the pump. I'm going to try this test once it warms up to be sure as it seems like a quick and easy test with no real special items nessecary.
Sadly, your stuck with the filter. The fuel flow test is a good way to test it, though. I've gone around so many times with this stuff that I've started using aftermarket pumps with aftermarket serviceable filters. I've had one turbo motor lunch pistons twice over this (slow learner), and it almost lunched one on the LSR bike last year... Thank god for datalogging and water injection!

If you're really going to push the performance envelope on the bike for a few years, I'd recommend some sort of AFR failsafe device or changing the pump/filter set-up to something you can service every season.
 

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Discussion Starter #5
That sucks but wouldn't you see the same effects on cylinder one if it has similar cooling?

I just had my injectors flowed and found one of mine was stuck shut. Think you could've had a stuck injector on that cylinder too?

Edit: Also how do you service the fuel filter? I tried looking up the process in the service manual and it says The fuel filter is built into the fuel pump and can not be cleaned or checked."

I also saw when poking around the manual on how to test of the fuel pump is working properly or if the fuel filter is possibly clogged or a problem with the pump. I'm going to try this test once it warms up to be sure as it seems like a quick and easy test with no real special items necessary.
They tested the injectors shortly after removal and they all came back fine - they initially thought it was. I'm not sure about all the terms, but the filter I'm referring to is that little 'teabag'. It looks like the attached image. I spoke to Kawasaki here in Cape Town and they recommended to replace it on each service with the one from Suzuki GSXR, apparently it fits and is a better filter - you can replace them.

I found this on the forum also: How To: Service Fuel Pump and Strainer - ZX6R Forum - so I assume the word I'm looking for is strainer...not so technical when it comes to these things :| But I'll be doing this from now on..it was a expensive fix...R68 000, which is probably $6000 roughly.
 

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Discussion Starter #6
Welcome!

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 :smile2: 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 :smile2:

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...
 

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Discussion Starter #7
That sucks but wouldn't you see the same effects on cylinder one if it has similar cooling?

I just had my injectors flowed and found one of mine was stuck shut. Think you could've had a stuck injector on that cylinder too?

Edit: Also how do you service the fuel filter? I tried looking up the process in the service manual and it says The fuel filter is built into the fuel pump and can not be cleaned or checked."

I also saw when poking around the manual on how to test of the fuel pump is working properly or if the fuel filter is possibly clogged or a problem with the pump. I'm going to try this test once it warms up to be sure as it seems like a quick and easy test with no real special items necessary.
No sure why my first reply didn't show..sorry for that. Basically, they tested the injectors and it came back clean - no issues at all. As for the fuel filter, I found this thread: How To: Service Fuel Pump and Strainer - ZX6R Forum - I think I'm using the wrong term :smile2: It's the little 'teabag' thingy I'm referring to. I was also told by Kawasaki to use the Suzuki 'teabag' (Sorry, not sure what it's called so I'll just go with teabag for now) since it's much better and fits.

I'll replace each service and get the AFR every now and then just to be safe..me personally.
 
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