Yike's, cracked piston, now quiet engine

[ohgood]

53 minutes ago, Bermudacat said:

All those deposits on the piston are coming from something. ?

maybe it's from burning oil and gas line it's going out of style

?

[shuswap1]

3 hours ago, bucket list said:

So do you think too lean will cause pinging on these engines, or is it more related to octane/compression.

I kinda think you'd feel some power irregularity due to lean before it was seriously pinging. I sure can hear mine rattle if I don't use the right octane, although it only does that with enthusiastic throttle application. What MJ were you using at highway speeds...I was on the lean rattle side with the 142.5 in the BSR when down at the coast.....and really should have upped the flow by one step.

[bucket list]

I kinda think you'd feel some power irregularity due to lean before it was seriously pinging. I sure can hear mine rattle if I don't use the right octane, although it only does that with enthusiastic throttle application. What MJ were you using at highway speeds...I was on the lean rattle side with the 142.5 in the BSR when down at the coast.....and really should have upped the flow by one step.

Ya, i run a 145 main and it runs really well, but still lean, the plug is whiteish.
I love that the engine is so quiet now, only on hard acceleration can you hear a bit of engine knock, which i believe you'll get with any single cylinder four-stroke. It's certainly not pinging, i'm running the full base gasket and good fuel, so who knows why that piston cracked. At least now i'll be heading out on my two long trips this summer with alot more confidence in this engine. Yaaahooooo, can't wait.[emoji3]

[bucket list]

2 hours ago, Bermudacat said:

All those deposits on the piston are coming from something. ?

You don't think that's a normal amount of deposits for a very worn set rings?

[g steezy]

6 hours ago, bucket list said:

You don't think that's a normal amount of deposits for a very worn set rings?

I thought so personally.

[Beta300REcat]

7 hours ago, bucket list said:

You don't think that's a normal amount of deposits for a very worn set rings?

I think it's normal for a set of rings that have a varnish load in them from running dino oil.

The crack I don't think is normal. 

Edited April 19, 2018 by Bermudacat

[Gary in NJ]

15 hours ago, Erik Marquez said:

Preignition or detonation or pinging can be a light pinging, no real felt loss of power, but its still like hitting the piston with a hammer all the way to heavy pinging which is like hitting the piston with a BIG hammer and you might feel loss of power.

Sounds like your describing detonation like might happen in atop fuel drag motor,,, yes, true, things go bad in a hurry and power goes off, things buts  and melt.
but that's not what is common on bikes running gas with too low of octane to control the pre ignition.   Every little ping you hear as you whack the throttle open under load is hammering away at the ring lands and whole piston as well. 
 

Not disagreeing...just giving some background. I built an aircraft many years ago. In this process I removed the magnetos from the engine and replaced them with an electronic ignition. The "mags" provide two stages of fixed timing; @TDC for starting (below 500 rpm) and 25 BTDC for all operations. I replaced the mags with an ECU that allowed me to adjust timing based on rpm, manifold pressure and altitude. The manufacturer of the kit suggested I set the max advance at 42 degrees @ 2,700 rpm and 25 in. mg. During test flight of the electronic ignition I experienced detonation at high rpm/high MP. It was something that scared the crap out of me. It felt like some one threw a lawn chair through the prop. I backed the advance to 40 BTDC and it continued to happen a few times, so the timing was further reduced to 38 BTDC. Problem solved.

Detonation (not pre ignition or pinging) is violent. Even though it was a single power stroke on a 4 cylinder engine, it shook the entire airframe and it felt like I was punched in the chest. Most people talk about detonation but are really describing pre ignition. Detonation is something that breaks stuff and isn't confused with anything else - once experienced (especially at 8,000').

 

Edited April 19, 2018 by Gary in NJ

[Erik Marquez]

36 minutes ago, Gary in NJ said:

Not disagreeing...just giving some background. I built an aircraft many years ago. In this process I removed the magnetos from the engine and replaced them with an electronic ignition. The "mags" provide two stages of fixed timing; @TDC for starting (below 500 rpm) and 25 BTDC for all operations. I replaced the mags with an ECU that allowed me to adjust timing based on rpm, manifold pressure and altitude. The manufacturer of the kit suggested I set the max advance at 42 degrees @ 2,700 rpm and 25 in. mg. During test flight of the electronic ignition I experienced detonation at high rpm/high MP. It was something that scared the crap out of me. It felt like some one threw a lawn chair through the prop. I backed the advance to 40 BTDC and it continued to happen a few times, so the timing was further reduced to 38 BTDC. Problem solved.

Detonation (not pre ignition or pinging) is violent. Even though it was a single power stroke on a 4 cylinder engine, it shook the entire airframe and it felt like I was punched in the chest. Most people talk about detonation but are really describing pre ignition. Detonation is something that breaks stuff and isn't confused with anything else - once experienced (especially at 8,000').

 

Agree, I think we are describing the same thing, Just it is felt differently in small aircraft (some experience flying in single engine high wing AC in Alaska ) then it feels in a motorcycle 

Knocking, pinging, pre ignition, and detonation in the auto and motorsports world is all the same thing as far as the terms go..That was my point .. And no matter what you call it, in a bike, short of it being catastrophic in action from something really wrong, I dont know anyone (except you...lol) that would say it "feels violent"
 

Quote

 

Knocking (also knock, detonation, spark knock, pinging or pinking) in spark-ignition internal combustion engines occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.

The fuel-air charge is meant to be ignited by the spark plug only, and at a precise point in the piston's stroke. Knock occurs when the peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive.

Knocking should not be confused with pre-ignition—they are two separate events. However, pre-ignition is usually followed by knocking.

The phenomenon of detonation was first observed and described by Harry Ricardo during experiments carried out between 1916 and 1919 to discover the reason for failures in aircraft engines.[1]

 

 

[shuswap1]

If it was violent in the aircraft it likely involved a misfire, not just pre-ignition. I assume the a/c engine was a 4 cyl Lycoming and you will know with great certainty when one cyl misfires! Even momentary sends a very noticeable shudder through the airframe.

Edited April 19, 2018 by shuswap1

[BillDirt1]

Summu you guys & your theories lol

[bucket list]

6 hours ago, Erik Marquez said:

Agree, I think we are describing the same thing, Just it is felt differently in small aircraft (some experience flying in single engine high wing AC in Alaska ) then it feels in a motorcycle 

Knocking, pinging, pre ignition, and detonation in the auto and motorsports world is all the same thing as far as the terms go..That was my point .. And no matter what you call it, in a bike, short of it being catastrophic in action from something really wrong, I dont know anyone (except you...lol) that would say it "feels violent"
 

 

So with regards to my question on lean condition causing a Knock, I imagine when lean the combustion would just extinguish before giving the full power stroke, but not nessesarly causing a knock?

[Erik Marquez]

2 hours ago, bucket list said:

So with regards to my question on lean condition causing a Knock, I imagine when lean the combustion would just extinguish before giving the full power stroke, but not nessesarly causing a knock?

A lean air fuel mixture cannot by itself cause pre ignition as far as I know ( AKA detonation, knocking or pinging )
 

[BillDirt1]

A lean air fuel mixture cannot by itself cause pre ignition ( AKA detonation, knocking or pinging )

It certainly made a difference with my CR250R (may be irrelevant).
I've heard 4-strokes can tolerate lean a/f ratios better.
Not hi-jaking, just wondering myself & for the sake of bucketlist. If 4-strokes are exclude from pinging, even from a 'hypothetically' very lean condition ?

[Erik Marquez]

32 minutes ago, Diverdown said:

Not hi-jaking, just wondering myself & for the sake of bucketlist. If 4-strokes are exclude from pinging, even from a 'hypothetically' very lean condition ?

Pre Ignition is physically what is happening = The AF mix is igniting prematurely before the specified timed event and without the spark.
Detonation= the AF mix combusts in an explosive manner after it pre ignites.  
Pinging= the sound you hear as the AF mix combusts prematurely and hits the piston well before TDC

All that said, Lean mix on its own, I wont claim to be positive with R&D behind my answer, but though observation and a few years doing this I dont believe a lean mix can directly cause pre ignition... 
I suppose how every, a very lean mix could raise cylinder temps so high, that what AF mix does come in, could ignite immediately..... But Id thing on a 4 stroke it would be all but in rideable if it was that lean. 
Its a good question, I've never considered as its not something that has come up and needed solved. 

[bucket list]

2 hours ago, Diverdown said:

It certainly made a difference with my CR250R (may be irrelevant).
I've heard 4-strokes can tolerate lean a/f ratios better.
Not hi-jaking, just wondering myself & for the sake of bucketlist. If 4-strokes are exclude from pinging, even from a 'hypothetically' very lean condition ?

Ya that's why I asked, the old racing 2 strokes run lean would ping like crazy and of course seize if you let it go too long. I like running the DRZ lean down here on the coast for good gas mileage and so it still runs well up in the mountains. Cheers guys.

[Beta300REcat]

4 hours ago, Diverdown said:

It certainly made a difference with my CR250R (may be irrelevant).
I've heard 4-strokes can tolerate lean a/f ratios better.
Not hi-jaking, just wondering myself & for the sake of bucketlist. If 4-strokes are exclude from pinging, even from a 'hypothetically' very lean condition ?

4t's can ping, knock and detonate.

Lean engines run hotter, hotter engines tend to ping, knock and detonate. Engines with carbon buildup in the combustion chamber don't quench as well, which tends to cause pinging, knocking and detonation.

So, if you had a lean 4t that also had carbon buildup................................

[Beta300REcat]

13 hours ago, Gary in NJ said:

 The manufacturer of the kit suggested I set the max advance at 42 degrees @ 2,700 rpm and 25 in. mg. During test flight of the electronic ignition I experienced detonation at high rpm/high MP. It was something that scared the crap out of me. It felt like some one threw a lawn chair through the prop. I backed the advance to 40 BTDC and it continued to happen a few times, so the timing was further reduced to 38 BTDC. Problem solved.

Detonation (not pre ignition or pinging) is violent. Even though it was a single power stroke on a 4 cylinder engine, it shook the entire airframe and it felt like I was punched in the chest. Most people talk about detonation but are really describing pre ignition. Detonation is something that breaks stuff and isn't confused with anything else - once experienced (especially at 8,000').

 

Sounds way too advanced for such a low rpm engine. I guess av gas is formulated to really resist detonation, though.

Like crack pistons?

I had a B2000 that would carbon up and detonate. You could feel it in the steering wheel, floor pans etc. Not a comforting feeling; definitely tugs the ol' pucker string. I can imagine that at 8,000 feet it makes you hairs stand on end.

[shuswap1]

I don't see the carbon build-up as unusual for a well-used engine. I also doubt that pre-ignition caused the crack,  nor a lean condition. The piston crown shows no obvious distress and that looks like a stress-relieving crack, concrete does that too, ya know?

Edited April 20, 2018 by shuswap1

[bucket list]

12 hours ago, Bermudacat said:

4t's can ping, knock and detonate.

Lean engines run hotter, hotter engines tend to ping, knock and detonate. Engines with carbon buildup in the combustion chamber don't quench as well, which tends to cause pinging, knocking and detonation.

So, if you had a lean 4t that also had carbon buildup................................

So you really think the T6 5/40 oil would not carbon up the cc as much?

Hoping with new cyl piston and rings it will stay cleaner, longer. I'll probably have the top end apart again this winter after my big loop through the western states.

[shuswap1]

The T6 contains excellent additives, including those reduced/removed from gas engines in the quest for longer emission system life. It is similar to the Mobil1 Turbo Diesel Truck oil, the 5w-40, although the TDT oil is not certified for wet clutch. I think it might better resist the build up, but maybe not so much as to justify the extra cost, not with our frequent oil changes.

The T6 also starts with a very high anti-acidification component, base index, which aids in longer oil life.

That isn't much carbon for that many miles, what ya bitchin' bout, Bud?