ConRod Babit bearing failure

[Swann]

It's a 2011, will some heavy mods. Pistons, cams and carbs.

Oil is SM rated, full synthetic
Oil levels were fine
It just ran through a break in from the engine being freshened up.
Oil is replaced every 1,000 miles

I use a forever oil filter, where the paper element was replaced by stainless steel screens, which makes it washable.

The bike does some street, but mostly it's a track bike.

Any ideas to the cause?

[jkv45]

Originally Posted by Swann

It's a 2011, will some heavy mods. Pistons, cams and carbs.

Oil is SM rated, full synthetic
Oil levels were fine
It just ran through a break in from the engine being freshened up.
Oil is replaced every 1,000 miles

I use a forever oil filter, where the paper element was replaced by stainless steel screens, which makes it washable.

The bike is does some street, but mostly it's a track bike.

Any ideas to the cause?

What oil?

How far did the engine come down?

Did it lock-up tight?

[dcj13]

Did you use assembly lube when you put it together?

Don't know about bikes, but on cars, one wants to pressurize the oil galleries before starting the rebuilt engine the first time. (Is that even possible on motorcycle engines?)

[Motofool]

Originally Posted by Swann

It's a 2011, will some heavy mods. Pistons, cams and carbs............

Any ideas to the cause?

Probably causes are three:

- The applied load could have been too big for the capability of the soft (Babbitt) material of the bearing, especially if auto-detonation was happening at operational temperature. Once the gap gets bigger, the film of lubrication disappears and metals contact, temperature rises and fusion begins.

- Pressure of oil was insufficient, load was enough to break the film of oil, metals contacted for a while without a continuous pressurized supply of lubricant.

- Contaminated oil (water, coolant, dirt). SM rated oils can damage flat bearings due to reduced anti-friction additives intended to protect catalytic material.

Please, read these:

http://www.aa1car.com/library/us1097.htm

http://en.wikipedia.org/wiki/Babbitt_%28metal%29

http://www.aa1car.com/library/us697.htm

[alex.s]

excessive redlining+high rev engine braking seems to accelerate the damage to that big end of the rod.

how long ago did you add the pistons? whats your break in method? sounds like motofool's got the right answer with wrong oil?

[jkv45]

Originally Posted by alex.s

excessive redlining+high rev engine braking seems to accelerate the damage to that big end of the rod.

how long ago did you add the pistons? whats your break in method? sounds like motofool's got the right answer with wrong oil?

A customer of mine races a SV and was using standard Mobil1 10W-30 automotive oil (which I highly discourage) and found bottom-end bearing problems when he pulled the engine apart at the end of the season.

If you are racing, top-quality oil is the cheapest part of the entire process.

Run an Ester-based synthetic like Motul 300V or Redline, and make sure it's their cycle-specific oil. That way you can pretty much cross "lubrication related failure" off of the list.

The other thing I would look at is the "reusable" oil filter. An incorrect part or installation could cause that type of problem. Best to use a standard-type oil filter IMO.

[Swann]

The brand is "BlackGold", it's made in Singapore.

The engine was completely taken apart for the mod. We eyeballed all the parts prior to the mod.

No lock ups, just the crunching sound.

Originally Posted by jkv45

What oil?

How far did the engine come down?

Did it lock-up tight?

[Swann]

Yes, we did.

The failure only happened after a 500 mile break in run.

Originally Posted by dcj13

Did you use assembly lube when you put it together?

Don't know about bikes, but on cars, one wants to pressurize the oil galleries before starting the rebuilt engine the first time. (Is that even possible on motorcycle engines?)

[Swann]

The oil and the filter are the only non-standard components in the mix.

I did do some reading about the filter and it claims pressure stability in race conditions. But, it did say "better filtering than the paper element", which logically means flow should slow down if particles restrict flow.

The oil specification is compliant to the need, unless they're lying.

OH, poop.

Originally Posted by jkv45

A customer of mine races a SV and was using standard Mobil1 10W-30 automotive oil (which I highly discourage) and found bottom-end bearing problems when he pulled the engine apart at the end of the season.

If you are racing, top-quality oil is the cheapest part of the entire process.

Run an Ester-based synthetic like Motul 300V or Redline, and make sure it's their cycle-specific oil. That way you can pretty much cross "lubrication related failure" off of the list.

The other thing I would look at is the "reusable" oil filter. An incorrect part or installation could cause that type of problem. Best to use a standard-type oil filter IMO.

[jkv45]

Originally Posted by Swann

The oil and the filter are the only non-standard components in the mix.

I did do some reading about the filter and it claims pressure stability in race conditions. But, it did say "better filtering than the paper element", which logically means flow should slow down if particles restrict flow.

The oil specification is compliant to the need, unless they're lying.

OH, poop.

I would ditch that oil filter. It could very well have created a flow restriction.

I've never heard of that oil, but it does claim to have everything you need - and more - for your use. I might try a different brand, or try to find some independent test results for it before using it again.

[fast1075]

Need pictures of the failed parts. Is there any evidence of seizure on the pistons or cylinders? Are the bearings on both rods failed, or only one? Are the crank bearings ok, or also failed?

Failed after a 500 mile break in? Usually that means it was not run hard until after the break-in, then run hard and failed. A gross assembly or machining error would have failed it immediately, not after 500 miles.

I have over the years seen several plain bearing engines THAT HAVE BEEN MODIFIED fail exactly this way. They ran "fine" until after break in, then ate the rod bearings. The culprit was the pistons, or more specifically, the clearance and materials the pistons were made from.

If you buy pistons (especially "forged" pistons) that are made with a low silicon content, they expand a lot when hot. Stock pistons have a high silicon content and are thermally more stable. If a set of low silicon pistons is installed with the same clearance as stock, or hypereutectic pistons, they will thermal seize, killing the rod bearings. Another possibility is rings that have insufficient end gap.

[Swann]

Pics will follow on Tues. I'm buying the replacement parts on Monday and going to the shop to document the damage.

Only 1 bearing failed (right side) everything else is cherry.

[alex.s]

Originally Posted by fast1075

If you buy pistons (especially "forged" pistons) that are made with a low silicon content, they expand a lot when hot. Stock pistons have a high silicon content and are thermally more stable. If a set of low silicon pistons is installed with the same clearance as stock, or hypereutectic pistons, they will thermal seize, killing the rod bearings. Another possibility is rings that have insufficient end gap.

i've been recently learning about steel and you obviously know your ****, i was wondering if you could explain more about the type of steels they use for pistons? it's oil bathed so i would think it's just straight up eutectic steel with typical sc and mag? and no protectors? you mention high silicon... are you talking more than 1%? is there a specific type of steel they typically use for pistons? i mean it's obviously not o1.... but would they use something as simple as say, 1080? i'm assuming they are straight pearlite because of the heat cycling?

[fast1075]

To clear any confusion, pistons are made of aluminum alloys. I am no metallurgist by any means, and deep technical info is best researched. But the basics are easy to grasp.

Most pistons are cast. The stock pistons in a 250 are made this way. The technique is called Die Casting. The basic piston is cast in a multi part die, and is then finish machined. The skirts, and pin bosses, and ring lands are the machined parts. This is an economical way to make pistons, and the alloy can be hard enough for good thermal qualities, and low expansion rates.

The down side of cast pistons are that they are subject to cracking under conditions of detonation when used in severe applications where mechanical shock occurs, such as detonation, and very high cylinder pressures.

The very hardness of the alloy that gives long wear life and good thermal properties are the problem when used in a severe application. They are the BEST general choice for most engines.

A more modern variation is the "hypereutectic" alloys that allow even tighter clearance and supreme thermal control. They contain silicone and other materials in very high amounts. The trick is not in the metalurgy, but in the process. The metal has to be "stirred" to keep the silicon in suspension. This is done by a variety of methods depending on the manufacturer.

An analogy is to picture a glass of tea with a lot of sugar poured in it. If you let it sit, the sugar settles to the bottom, but if you keep swirling it, it stays in suspension. Now picture instantly freezing the tea as it is swirled, capturing the sugar in solid suspension.

A hypereutectic piston is not a good choice for severe applications, but has a far better service life, can be set up much tighter, and as a result, give better oil control and reduce emissions. Modern engines owe their long service life in part to these pistons.

"Forged" pistons start out with cast blanks similar to any other pistons. During manufacture, the piston blanks are placed into forging dies, where heat and pressure (tons and tons of pressure) shape them and force the molecular structure of the alloy into crosslinked crystals. This increases their fatigue resistance WITHOUT increasing the hardness. Unfortunately, the alloy used must be low in silicon to be ductile enough to be forged. The pistons stand up to hammering better, but still have all the ills of a low alloy content.

Lacking the silicon, the alloy is soft, with poor wear properties and suffers from excessive thermal expansion. (But they can better stand up to abuse without breaking).

For example, a KZ-650 engine with stock cast pistons is safe with a .0015 cylinder clearance with stock pistons, With old school MTC Engineering forged pistons need .005 clearance or they will seize. Modern pistons, such as those from Wiseco fall in the middle, with some others, such as high end Mahle pistons being as good clearance wise as the stock cast pistons.

[quarterliter]

Originally Posted by alex.s

i've been recently learning about steel and you obviously know your ****, i was wondering if you could explain more about the type of steels they use for pistons?

Steel pistons that's a new one!

Disclaimer: Some new diesel engine designs are using steel pistons.

Regardless nice writeup fast!

[alex.s]

hypereutectic silicon in aluminum! that's so awesome! god damn crystals are friggin cool.

[Swann]

The pics will have to wait another week. The parts dept. doing their annual inventory till January 12.

[alex.s]

Originally Posted by quarterliter

Steel pistons that's a new one!

Disclaimer: Some new diesel engine designs are using steel pistons.

Regardless nice writeup fast!

http://www.gizmag.com/mercedes-steel-pistons/33415/

any idea what kind of steel it is? i would assume high Sc, C, Mn and maybe like vanadium so it doesn't disintegrate? but how are they keeping the grains small enough to be structurally sound with so much heat differential top to bottom? must be a really nice cooling system underneath.

[quarterliter]

Originally Posted by alex.s

http://www.gizmag.com/mercedes-steel-pistons/33415/

any idea what kind of steel it is? i would assume high Sc, C, Mn and maybe like vanadium so it doesn't disintegrate? but how are they keeping the grains small enough to be structurally sound with so much heat differential top to bottom? must be a really nice cooling system underneath.

Maybe you could do some more googling to find that one out. Or just ask siri.

That gizmag article was the one I was referencing in my previous post. You know the one about new diesel designs.

[alex.s]

spent some time looking but couldn't find any good info which is why i asked :/ lots of info on rotors though

[Somchai]

Originally Posted by alex.s

spent some time looking but couldn't find any good info which is why i asked :/ lots of info on rotors though

As a short info: Pistons from steel are used in Diesel-engines, so mainly in trucks.
Audi and also Peugeot are using them in their 24-Hour-Le-Mans racing cars (Diesel).
They are lighter than pistons from aluminum, the engine runs a little bit more fuel-efficient but they'll become hotter.
On the picture left piston is from aluminum, right is from steel.

[dcj13]

Originally Posted by Somchai

For a given engine (same crank an con rods), piston on right will provide a lot lower compression ratio...

(Captain Obvious to the rescue!)

[alex.s]

you can always tell a heavy duty diesel piston by the mexican hat on top.

[quarterliter]

Interesting. I never knew that the diesel LMP1 cars used steel pistons. I wonder what material characteristics they exploit vs alloy in order to make lighter pistons as Roland suggested.

[Somchai]

Originally Posted by quarterliter

Interesting. I never knew that the diesel LMP1 cars used steel pistons. I wonder what material characteristics they exploit vs alloy in order to make lighter pistons as Roland suggested.

In case you didn't read it up to now http://audi-encounter.com/magazine/t...-at-the-limits

[Somchai]

Originally Posted by dcj13

For a given engine (same crank an con rods), piston on right will provide a lot lower compression ratio...

(Captain Obvious to the rescue!)

- I think you don't want me to answer here, since I'm pretty sure you'll know that the conrod will be longer to keep the compression heigh on its level, by the way the difference is 14mm.

[quarterliter]

I actually just read that exact same article Roland. Very interesting.

[Swann]

The result is in : A conrod bearing broke in half.

Thankfully nothing else was damaged.

[Motofool]

Originally Posted by Swann

The result is in : A conrod bearing broke in half.

Thankfully nothing else was damaged.

That is not a typical failure.

Could it be that the shell was not equally backed up all around the housing of the rod and it suffered fatigue?

[Swann]

After replacing the damaged parts, it happened again, only worse this time.


Any ideas?

[micoulisninja]

goodness Jake ! this is major damage!
One thing I suggest for sure is to switch back to stock oil filter and a known brand's oil with sae 10w-40, not other...
but this one I see, even if I can't make out for sure is some measurement mistake...
check, doublecheck and verify that rod 1 goes to cyl 1 assembly rod 2 goes to cyl 2 etc, each rod back end is the one that the factory set as pair to the upper part and thickness of bearings are not the ones suggested only by colors and marks on rods and casings but also by measuring crank thickness and rod inner diameters...after triplechecking that, check for rod free play when bolted in place and definetely do NOT overtighten rod bolts ! also you have to check the roundness of the inner surfaces of the rod and of course of the crank to verify there is no warp, seizure etc of the mating surfaces to the bearings...
by the way I believe it is imperative to use genuine kawa bearings and not aftermarket ones...
finally do not forget to check all oil squirters for dirt or clogging
I would justify such damage within such minimum time only if crank had been lightened and not rebalanced or if something is totally warped...
one last question... I believe you are using high comp pistons... are they stock dimensions or oversize ?
I am asking this because if oversize then it means that you had the cyl block rectified... and while it might seem to be totally round when measuring at top middle and bottom and at same dimensions, it is not totaly sure that the cylinder is totally straight throughout the piston's travel... I hope you can understand what I mean...
I have seen "banana-shaped" cylinder blocks that when measured gave figures of total roundness and equal dimensions throughout the piston travel...
anyway I really wish you find out what is wrong there and give us your feedback...
I hope you will overcome that issue as soon as possible and enjoy your ride once again !

[jkv45]

Originally Posted by Swann

After replacing the damaged parts, it happened again, only worse this time.


Any ideas?

Whoa - what a mess! I would expect a blocked oil passage or inadequate oil flow or oil pressure.

[Ghostt]

Nicely done sir, I'm impressed, and I've destroyed a lot in my old drag racing days.

You did say you "eyeballed" it????? Seriously??? So no precise measurements........ Huh.

So the rod bearings are failing, installed improperly, did you check clearances? Crankshaft checked? Rods? Oil galleries?

It's had to tell from a picture, More pictures would be helpful, like the crankshaft, rods, etc...but I'd say start with the basics and work your up.

Is the engine stock? What modifications have been done, and by whom? How long did the engine run before the failure? How was it running before it happened? Etc..... This is a simple problem, but a long list of variables for sure.

Good luck

BTW you happen to install a Big Bore kit?

[fast1075]

This damage is known as a spun bearing. The bearing seized to the crank and "spun" inside the large end of the rod until it burned it up. Steel (the bearing shell) has to get VERY hot to turn blue like that.

Did you replace the damaged rod and crank when it failed the first time, or just install new bearings?

This time FOR SURE the crank and rods are toast. Do not try to reuse them. Find a crank with matching, assembled rods. OK, you can have the crank fixed, but it will cost far more than a good used one.

Logic: If the main bearings are in good condition, the rod did not fail from oil blockage unless the crankshaft passages are blocked because the rods are lubed by the same feed that lubes the crank bearings.

Post some pictures of the piston skirts and cylinders, and the main bearings, as well as the crankshaft.

I'm still betting on excessively tight piston/cylinder clearance. If that is in fact the case, the evidence will show on the pistons. Post up some clear pics.

[Ghostt]

Logic went bye-bye, when eyeballing entered the room.

[Swann]

Thanks for the inputs guys.

The bike has the following internals installed.

JE Pistons : 13.5:1 282cc pistons
Ported
Synthetic oil
Beet Cam
Flo oil filter (stainless steel)
Fuel is 100 ron
31mm Yoshimura Keihins
BRT Dual band CDI

When I had the JE 265cc 12.5:1 kit, everything was cherry. It ran great, both on and off track(4.1 kms.), giving power all the way to 14,500 rpm, which I cautiously reduced to 13,500 rpm.

There only difference is the cylinder kits.

But unlike the 265 kit, the 282 kit had considerable drop in power before reaching red line. There wasn't any follow through in the power delivery.

Parts were measured and oiled before installation, oil channels were cleaned and the oil pump works just fine.

I had dynoed the bike with the 265, it put out 37hp. After installing the 282 kit, I do some tests(800 kms. of testing) before slapping it on the Dyno. The engine failed before I could do that.

[Swann]

The term "eyeball" was only used because, I didn't personally see the damage and there were requests for pictures, which wouldn't happen till I get to "eyeball" the engine. The mechanic had "told" me what happened.

I'm not the mechanic.

Please go easy on the comments till you have the facts.

[cuong-nutz]

Wow, can't believe I missed this thread in it's entirety. I'm in agreement with Harry all the way on this one.

[Racer x]

It just looks like an oil problem. Let me read up on you other posts. It's difficult to know what is going on. Does the mechanic have experence with this sort of engine work?

[bruce71198]

Detonation can hammer a bearing out like that. Fuel delivery on that cylinder could be an issue....
800km of street riding won't uncover what a few hard dyno runs will.