Mr Mustang

[BruKen]

As a supplicant to the Triumph Guru can you possibly explain this to me..

These are my liners. I checked and double checked and no, the engine has never had piston or liner replacements in it's 30k mile lifetime. How is it that the honing marks are still visible and only marginally worn down from those at the bottom where the piston and rings dont reach? Tried to run the bike in on full synth?


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[Sin_Tiger]

I can't see evidence of glazing of the surface but try wiping it with a vinegar soaked clean white rag (unless you've already cleaned the surface, if it comes away brown then that indicates low temperature laquering, i.e. some of the oils components have not been consumed and formed a hard laquer on the liner that prevents the rings sealing, combustion gas gets past the rings, they overheat and quite quickly loose the remaining sealing capability.

If this is the case, i.e. you get brown muck, then you must have the liners honed, I would recommend a line hone in any case, just changing the rings will simply repeat the cycle.

[Mustang]

:icon_scratch
no idea
really soft piston rings  

I had a set of liners kicking around before I cleaned out the old shop and moved , they were from the engine with the picture of the piston with the blown big end bearing . If I recall correctly They still had the cross hatching clearly visible also at 28k ,maybe it's a triumph thing
the motor never burned oil either and ran fine until #3 didn't want to be attached to the crank anymore

do you know that syntetic oil and dino oil are one and the same ?

castrol rep explained to me once upon a time that synthetic is just highly refined until all of the molecules are the same size , he said it all comes out of the same hole in the ground . and of course the additive pkgs. are different for different flavors of oil .

[BruKen]

well one theory offered so far has been

Undersize piston and rings on full synth with cold plugs on low octane petrol and never run hard enough to reach full operating temperature

I'd be interested to know if anymore people have noticed similar, as the bike, as it stands is all factory built. The original owner was a meticulous hoarder of receipts. Everything was done at the dealers including oil changes.

Sin, these have been cleaned with a bit of degreaser and then coated in WD40. As for their original state so much gunk and sludge from residual coolant got in while lifting them and I had sprayed liberal amounts of oil into the liners via the spark plug holes before manually trying to turn the engine over that it's difficult to say what they looked like. I certainly haven't scrubbed them tho.

[Sin_Tiger]

With a properly run in engine that's been regularly serviced will have visible hatching until the rings are at their wear limit.

You remembered well, with apologies to any industrial chemists reading this, the reason traditional mineral oils break down is because they are taken out of the fractionating cloumn in a pretty 'rough' range of distillates which will include molecules of varying lengths and many that have easily broken chains. Synthetic oils are 'cracked' from higher level distillates which means the molecules can be very tightly controlled and hence do not break down very easily and do not 'collect' the products of combustion on the ends of the molecules.

The majority of 'dirt' we see in used oil is from combustion products, synthetic oils allow those products to be filtered out since they stay free in suspension, that's one of the reasons synthetic oil looks cleaner if you change it at the same mileage and teh oil in engines running on LPG stays cleaner and more robust longer, fewer combustion residues getting into the oil in the first place.

Additive packages are included in traditional oils to combat the instabilities and to deal with differing fuel grades around the world, Rotella is a good example, there are over twenty variants last time I looked, "high sulpher content in your local diesel sir, I have just the oil for you.

Enough it's late.

Line hone your liners, fit new rings and run it in with mineral oil as suggested by you local oil distributor, not the spotty yoof at Halfrauds.

[BruKen]

yes. You are right... found this

When a bore has been run in, all the peaks will have been cut or worn off, leaving the honing grooves. These grooves act as oil reservoirs for lubricating the bore and spreading the oil round the cylinder wall as the rings pass over them. Too much oil retention (if the grooves are too deep or there are too many of them -- the cylinder is 'rough') and the oil consumption will be high.

Not enough oil retention (so if the honing grooves are too shallow, not enough or at an angle where the oil drains too quickly) and the cylinder bore will wear prematurely. This will be a 'smooth' bore, in which wear occurs because there is too much contact area for the rings against the bore, which in effect gives micro-friction welding and breaking of the rings to the cylinder wall.

http://www.realclassic.co.uk/techfiles/ ... 10600.html (http://www.realclassic.co.uk/techfiles/tech05010600.html)

based on this I am a bit reluctant to perform a home DIY job to these liners  using a cheap tool like so, and taking it to a engineer shop starts eating into the rationale for not just replacing them. Also the rings are in good nick, and you cant seem buy them seperate from the piston (they come as a set. Leave as is would save me 3 x £53 for the liners and 3 x £71 for the pistons, so, leave alone / DIY rehone sans new rings / fork out wads of cash in the bottemless maw of the tiger and do the job "propper like"?

[Sin_Tiger]

Without some very expensive kit or 30 yrs looking at liner bores  :roll: it's going to be difficult to judge if you've got it right. There is a reason it's not 5 quid per bore! If you are going to keep the bike and ride it, save yourself the grief.

I am almost certain it'll be possible to get rings separately, Triumph sure as hell don't make them  

[BruKen]

You are right of course. Yet more money into the tiger's maw
I should ask admin to change my username to YAPI too :lol:

[JetdocX]

Sorry, I don't have any good shots of mine.  I do remember cleaning the bores out with MEK and putting a nice coat of oil back on.  The crosshatching was still there in mine as well.  38,000 miles.