Stuck rings

[Meds]

Agree completly, these threads are really interesting.
I'm running EXoil fully synthetic in 2 motors (one iron, the other Nickasil) at 4%, I have done around 2000 miles between them and haven't had a problem. I changed due to the good reviews.It's smokey on start up but seems to clear quickly.
The reason I'm interested it this fault has a common cause and we are blaming an oil, I think we should be looking at other contributing factors, like
Over oiling and running hot.
Fuel/oil additive reactions
Oil/heat/material interactions, ie something in the rings or piston acting as a catalyst.
If there are any chemists amongst us can they please add to the reasoning.

Just a thought, the oil is gumming up and solidifying in the rings causing them to stick. Symptom.
Could the oil be collecting in the area cooking off the lighter parts and leaving some form of tar that solidifies and shrinks as it cools.
That might sound daft, but two of the posters have said, running fine stopped and lost compression,
If the rings were jammed in before they stopped it wouldn't have run, so the ring positions are likely to have changed state after they stopped, hence the shrinkage and jamming.
This is only a hypothesis, and as such can be challenged/supported

[ToBoldlyGo]

I'm sure I've read it somewhere that fully synth is probably a bit excessive for everything except the more sporty engines. Basically it is too good, and because it coats so well doesn't get burnt off as it should. Could it leave residue that slowly gums your engine up, I wonder?

[Warkton Tornado No.1]

Re: Stuck rings
Post by ToBoldlyGo » Tue Jul 26, 2016 2:09 pm

I'm sure I've read it somewhere that fully synth is probably a bit excessive for everything except the more sporty engines. Basically it is too good, and because it coats so well doesn't get burnt off as it should. Could it leave residue that slowly gums your engine up, I wonder?
Re: Stuck rings
Post by Meds » Mon Jul 25, 2016 8:18 pm

Agree completly, these threads are really interesting.
I'm running EXoil fully synthetic in 2 motors (one iron, the other Nickasil) at 4%, I have done around 2000 miles between them and haven't had a problem. I changed due to the good reviews.It's smokey on start up but seems to clear quickly.
The reason I'm interested it this fault has a common cause and we are blaming an oil, I think we should be looking at other contributing factors, like
Over oiling and running hot.
Fuel/oil additive reactions
Oil/heat/material interactions, ie something in the rings or piston acting as a catalyst.
If there are any chemists amongst us can they please add to the reasoning.

Just a thought, the oil is gumming up and solidifying in the rings causing them to stick. Symptom.
Could the oil be collecting in the area cooking off the lighter parts and leaving some form of tar that solidifies and shrinks as it cools.
That might sound daft, but two of the posters have said, running fine stopped and lost compression,
If the rings were jammed in before they stopped it wouldn't have run, so the ring positions are likely to have changed state after they stopped, hence the shrinkage and jamming.
This is only a hypothesis, and as such can be challenged/supported

Sorry about this Meds!

I've said in other Posts that I've found that the Exol Optima (full synthetic) may well be 'too good' & have cut down to 2-1/2% with no issue (so far!) It is, after all, an oil designed specifically for air-cooled two strokes & I started using it in 2012.

I really hope that you can sort out the problem though, whatever it may be

[kennystag]

Hi Johnny xs,
It was grandpa who sent in the leak down test, his invention with the bicycle tube. Is that you giving the tornado more hassle, you just do not like to be proved wrong.

[Meds]

no need to be sorry,
I chucked out an idea, you have come in with 4 years worth experience and expanded the thinking, sounds like it could be over oiling and not running hot enough thats leading to gummed up rings.
Which is exactly the situation I could be in.
I dont have a problem with gummed rings at preset, with a little care, attention and listening to what other do I will hopefully avoid gummed rings.
cheers for the advice.

[kennystag]

Grandpas cracking leak down test for people that have not seen it.
Cheers
Stag

viewtopic.php?f=10&t=140&p=24624&hilit=leakdown+test#p24624

[davej]

Will add a couple more observations if I may-
One of my bikes is a completely standard SX200 after using Rock Oil I changed over to Exol, Back at the end of May rode from Southampton up to Shaftsbury however on the way back on encountering a long hill to climb I started losing power and had to change right down to second and ease the bike to the top. Back at home I stripped the bike and found a stuck Top Ring. This happened after riding approx. 4000 - 4500 miles using the Exol. Having re done the Top End have now done a 1000 miles still using Exol. The mixture I use is 50:1. Doubt in my mind do I carry on with Exol ?

Last weekend another one of club members travelling back from Exmouth on a Standard TV175 encountered the same problem on a rather long incline the bike give up completely. On stripping he found stuck rings and hole in Piston, He again had changed to Exol at the same time as myself and had done in the region of 4000 miles. Is this just a coincidence? or should we take these incidences as something more? Looking forward to more interesting comments!

[johnnyXS]

If the rings appear to be sticking due to burnt oil from exceptionally high engine temperatures as I have always suspected then it might pay to fit a engine temperature sensor or apply the temperature strips which show the maximum temperature reached.

I have not seen anyone yet mention what the manufacturers maximum recommended running temperature is for this oil used in 2 strokes . ?! ........we need to bear in mind that 2 strokes have absolutely no means of applying additional cooling as 4 stroke scooters and motorcycles have .

On a hot day on a long high speed run we hit a longish incline where an already hot engine is suddenly put under an extended load ........

Lambrettas and VEs*as have been using mineral oil for over 60 years without any issues that I am aware of .

[ToBoldlyGo]

I've just started 20 litres of the Exol and I'm going to use the bloody stuff if it kills me. Hopefully it ought to be fine as it's semi.

[Warkton Tornado No.1]

Post by davej » Thu Aug 04, 2016 11:16 am

Will add a couple more observations if I may-
One of my bikes is a completely standard SX200 after using Rock Oil I changed over to Exol, Back at the end of May rode from Southampton up to Shaftsbury however on the way back on encountering a long hill to climb I started losing power and had to change right down to second and ease the bike to the top. Back at home I stripped the bike and found a stuck Top Ring. This happened after riding approx. 4000 - 4500 miles using the Exol. Having re done the Top End have now done a 1000 miles still using Exol. The mixture I use is 50:1. Doubt in my mind do I carry on with Exol ?

Last weekend another one of club members travelling back from Exmouth on a Standard TV175 encountered the same problem on a rather long incline the bike give up completely. On stripping he found stuck rings and hole in Piston, He again had changed to Exol at the same time as myself and had done in the region of 4000 miles. Is this just a coincidence? or should we take these incidences as something more? Looking forward to more interesting comments!

I had to think carefully about to reply to this.

Suspicion of the oil could be well founded, but I doubt it simply because of the major clue. That is the fact that the piston has overheated &, in some examples mentioned, actually been burnt through as a hole! My belief is that stuck rings are symptomatic of overheating.

My honest opinion is that the reasons for that will be any, or a combination, of the following:

Air leak
Squish too high
Spark plug range
Compression Ratio too high
Octane of the fuel
Ignition problems
Lean carburetion

If I appear defensive of Exol, I'm not being so. However, I am open-minded about fully synthetic oils, Mineral & even Castor oils.

They all have their place if used in the right manner.

I apologise in advance if I cause any offence, but I can’t help think that there is a tendency to blame factors so often in these threads that all too often turn out not to be the problem.

[ToBoldlyGo]

That's very true White Tornado. The fact of the matter is I've been using the fully synth variety for quite some time and never had a problem with it. As you say there are other factors that could be involved too. So we need to keep an open mind.

[johnnyXS]

Exol and I'm going to use the bloody stuff if it kills me. .

They'll write on your gravestone ' I told you I was gonna use Exol '....

I suspect that the majority of 2 stokes probably do just fine on Exol semi nearly all the time . it may well just be the odd scoot whose engine runs very hot for a certain period of time for some reason or other which could be weak mixture, air leak, sustained high speed running , poor heat disipation etc when the problem occurs.

It would be interesting to hear from some of the racers that use semi Exol if they have experienced any gummed up rings.

[davej]

Thanks! Interesting points already. I am not at a point of giving up on Exol and I doubt whether it could be proved its a problem. In defence of my SX it has always been a good starter and very reliable and I don't consider myself a racer. I have now ridden 24500 miles and my only real mishap was when my U bend came loose and out in a strong wind I almost holed the piston this was back at approx. 14500 miles. Back to the day of the Stuck Ring it was not a particularly hot day and had only been riding back approx. 4 miles before the hill. Maybe it was time to change the Rings at 10000 miles (new at 14500). I was waiting till I had done 12000.

[coaster]

.....Lambrettas and VEs*as have been using mineral oil for over 60 years without any issues that I am aware of .

You are forgetting that we had to do regular de-cokes back then which would include removing the rings and cleaning the groove with an old broken ring I suspect that the racers wouldn't experience problems for similar reasons i.e. regular top end strip downs.

[HxPaul]

Just as a matter of interest,is semi-synthetic oil mixed with mineral oil and thats what makes it semi,but fully-synthetic isn't.

[peejay]

hi peeps
after clubmate davej had told me of the sticking ring he found after stripping due to the loss of power up the hill (i was with him at the time),we discussed if it possibly could be the oil.

now that another clubmate has holed a piston after many miles we still are not sure as to the actual cause.

of course after thousands of miles of faultless running it comes as a nasty shock when it goes pop!

so the two scoots concerned here have cast iron barrels, not tuned and running as near as possible as innocenti intended and ridden at moderate speeds (45/50mph)

i'm also using exol fully synth on two motors.
1 RT 225, built new 6,000 miles ago, all miles on 3%, appears to still be running at full power but hasn't been stripped so far, motor is in a series 2 with no bling.

2 early mugello 225 built new 23,000 miles ago, at 10,000 miles i holed a piston shortly after filling up at a back street garage. barrel was cleaned up and new piston and rings fitted.
since that blow up the motor has not been touched in 13,000 miles!!
this motor had been running rock oil fully synth at 2% till 3,000 miles ago, now exol fully synth at 2%.
this motor is in a totally over the top modmobile and has to work very hard into a headwind and although it's no rocketship i don't think that my rings can be sticking at this time.
is it possible that rings are more likely to stick in a cast iron barrel as apposed to a nicasil lined ali one?

[johnnyXS]

.....Lambrettas and VEs*as have been using mineral oil for over 60 years without any issues that I am aware of .

You are forgetting that we had to do regular de-cokes back then which would include removing the rings and cleaning the groove with an old broken ring I suspect that the racers wouldn't experience problems for similar reasons i.e. regular top end strip downs.

blimey I didn't I just thrashed my li150 everywhere and apart from tuning and timing etc I never had the engine off.
I moved on to cars at 17 so I never got to enjoy the delights of decoking back then I was too busy painting my panels with brushing enamel paints and refixing my tank aerial

[ToBoldlyGo]

Just as a matter of interest,is semi-synthetic oil mixed with mineral oil and thats what makes it semi,but fully-synthetic isn't.

As I understand it semi has a mineral oil base and is bulked up with polymers and additives. Whereas synthetic is basically a dash of mineral oil with the bulk of it being synthetic. There's actually more oil in semi.