Cylinder down!

[alexis291]

Hi Folks,

I am trying to solve an engine conundrum and would welcome suggestions please...

My 50,000-mile K1100RS is running colder on cylinder two at idle and appears to be burning a little oil in that cylinder, judging by the condition of the spark plug. The plugs have done 5000 miles (I have now changed them all), and number two was noticeably different to the others, with some burnt oil deposits. Overall oil consumption is fine, the bike has always used a bit and that hasn't changed.

I've looked inside all the cylinders with my cheap eBay endoscope and, notwithstanding that the quality is not great, they all look pretty much the same.

I've tested the exhaust temperature with a plastic ty-wrap on the headers but only at idle, it may be okay when riding but I have no way of checking. Performance seems absolutely fine.

So I am wondering if the difference in that cylinder temperature might be down to an injector, but that wouldn't explain the oiled plug. I also thought that a fouled plug may be causing a misfire at idle, but number two exhaust temperature was low with brand-new plugs fitted.

For what it is worth, valve clearances are all within specification and cylinder pressures are all good (180 - 190 psi).

Any ideas?


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[Martin]

You can now buy a laser temperature gun pretty cheap around the $20.00 - $30.00 mark. I use mine to check even running by checking the temperature on the headers as close to the head as possible. I have to remove my belly pan to do this accurately. It did show up faulty injector spray patterns. If you have a bad injector, faulty lead or spark and  if you have left the bike on it's side stand it might not be able to burn the oil that inevitably leaks past the rings.
Regards Martin.

[Laitch]

I am trying to solve an engine conundrum and would welcome suggestions please...
Overall oil consumption is fine, the bike has always used a bit and that hasn't changed.
Performance seems absolutely fine.
For what it is worth, valve clearances are all within specification and cylinder pressures are all good (180 - 190 psi). Any ideas?

Go for a ride and quit obsessing.  :yippee:

[alexis291]

That may be the best advice I'll get! It will probably be the easiest one to carry out. Just waiting for the snow to clear...


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[alexis291]

Martin, thanks for the suggestion. I am sure my exhaust temps are different despite my crude method - but just at idle. If I could measure them under load (i.e. when riding) and they turn out to be the same I'll be happy and just take Laitch's advice. I could move injectors around and see if that changes which cylinder is cold. I'm puzzled why no.2 plug is fouled, possibly it's running a bit colder if the injector is faulty. It is the same colour as the other plugs. I'll check again with the new plugs after a few miles.


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[riots100]

If you don't get a full combustion in the cylinder, then you can get oil fouling since the lack of sufficient combustion will not burn away the oil that is there, thus fouling the plug over time.

[alexg]

Could you have an injector that does not close ?


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[Martin]

If you have a bad injector, faulty lead or spark and  if you have left the bike on it's side stand it might not be able to burn the oil that inevitably leaks past the rings.
Regards Martin.

[alexis291]

Work in progress...
Too snowy to ride / test atm. Will update with any developments.


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[Laitch]

Work in progress...
Too snowy to ride / test atm.

I won't be riding until May when the salt is off the pavement and the frost is out of the gravel roads where I live. I'm available to do some obsessing for you if you're too busy with enjoyment. Let me know.

[alexis291]

Thanks Laitch, good to know I've got a fretting buddy if I need one. If I wake up tonight in a cold sweat thinking about exhaust temperatures I'll be in touch.


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[rbm]

Could you have an injector that does not close ?

+1.  I had this condition once.  Took an IR thermometer and looked at the exhaust header temperatures with it while the bike idled.  Quickly identified Cylinder #2 as "cold" and swapped the injector.  Problem solved.

[alexis291]

I have now had my injectors flow tested and cleaned. Before cleaning there was a 5% spread in flow rates. After cleaning they are all the same and spray patterns are all good. Put them back on the bike but in different positions and - lo and behold - cylinder number two is still cold at idle. Spark plugs have also been replaced. Hmmmm. I think Laitch was right and I should just ride and ignore it.


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[Laitch]

This thread supports my belief that fondling exhaust pipes is a perverse distraction. :giggles 

Have you tried all the swapping combinations? What about the coils and the plug wires? There's plenty to occupy those cold, lonely winter nights. Can you really afford to relax? What about the all the holiday debt, and the extra weight gained by holiday feasting?

[alexis291]

Dammit Laitch, just when I was starting to relax! No, I haven't tried swapping any of the ignition system components. I did wonder about plug leads but had run out of enthusiasm when I finished working on the bike yesterday. That could be my next step in order to return to dream-free sleep.


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