At the end of the day you likely have more experience then me with bearings coming apart like this...as one of the bearings in question did actually come from you ... ...... not pointing fingers at you, just saying

I will happily admit this is not something I have really seen before, or at least not like this.....all the others I have seen have shown severe signs of the bearing piling up and peeling away at the race surfaces.....this one has cracked apart quite cleanly and was truly not subjected to any out of the ordinary abuse......

you can kill a bearing by skidding the balls......rapidly spiking the engine RPM before everything is fully warmed up can cause the balls to skid on the race and start tearing up the bearing surface..... Usually if this happens you will see pitting and scarring on the race like in the picture Monty posted.........

Also to add..I have seen similar damage from the bearings not being properly broken in properly.... new bearing, cold engine, rapid RPM spike..snap !

Sigh

I have seen a total of 12 different brngs (2 of which came from engines purchased through me) that have had this happen
Every one of them had alot of seizing going on , race stopped spinning or slowed in comparison to speed of rotation of the crank , superheated metal gets brittle , its like overhardening which is measured in rockwells , apply pressure to that metal and it snaps ..


Im not saying its not that the races havent been slightly overtempered when they were made but the heating/cooling / expansion/contraction that the metals see inside of these cute little micromotors takes the hardening process even farther


In my opinion

you can see that the bearing in the pic you posted had been seizing , likely due to harmonics or bad/lack of lubrication , see how the inside of the race where it meets the crank is discolored

In regards to The pics i posted , the pitting on the races is aftermath of the chunks coming out of the inner race

+1

+2+3+4 Tune and Maintenance some mills will have issues new most will show up early on or if someone doesn't know or hear these tail tail signs expect trouble - Kaboom

Also in regards to the pics posted...... My wife has sold bearings and analyzed them for 30+ years. I showed her the pics and she said, " lack of lubrication" without hesitating.....

Which in our case is caused by overlean conditions and also alot of the new wave fuels have very lil lube which is mostly synthetic

The thing is there are other areas of the engine that would usually show signs of lubrication issues before the bearing would explode....the crankpin and rod bushing would be showing signs of heat and wear...yet on the engine I took that bearing out of there is no signs of heat or lubrication issues...the crank pin is pristine and the bushing shows no heat damage.....the engine looks like brand new inside.......well other then the damage created by the bearing..........Usually if a guy runs a engine lean and hard the rod bushing will take damage that is usually very easy to spot......the crankpins will also show heat scarring and smear marks from the rod busing...and on this particular engine there are none of those signs...................

In the end I personally do not think this bearing exploded due to user error and because of that I am going to replace the entire engine since the bearing was purchased and installed by me.............the engine shows zero signs of running lean , and IMO if it was indeed run lean enough to explode the bearing there would be substantial scarring and wear on both the rod bushing and crankpin.............

Very interesting...I have had a Fire 11 for a bit with no problems and internals were always in mint condition but a fellow racer is on his 3rd one.
His first one lost a ball from the rear bearing destroying it...replaced by RB and his second did nearly the same..there was evidence of lake of lubrication on the second engine aswell but he had only performed 12 tanks on break in.
Both bearing failures were on the starter box..
I have a new BXR and really hope there isnt a issue with the nova bearings, I always remove the back plate and head and oil the engine before break in maybe thats the tip?
PS. Will Neal do a modded BXR as my clocked P5 is perfect

send me that BXR and I will put the magic to it...I have been making RB's sing like sirens for years !

Hey guys and girls, can I get a comment on these pics. It's my Roma and would like comments on condition. I'm using nitro x 30% and had a c7 plag in as temps were around 32dec cel.

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