ConRod Babit bearing failure

[Swann]

Updates :
@Racer x,

Yes, he very experienced with race engines, it's all he builds.

After the first breakdown, I changed the oil to a well known brand, but the same problem repeated itself.

The oil channels were cleaned and cleared, the pump works fine.



@bruce71198,

Originally, I was using 95 octane and did numerous rides, track days and races. It was stable. The change started when we installed new pistons, but didn't change the jetting. Later on, the mechanic noticed the inside of the exhaust was a bit grey.

He rejetted the carbs, I also switched to 100 octane(ron) fuel, I am considering using an octane booster and I'm breaking in a new set of pistons. I just did a track day and limited my rev limit to 10,000 and used the stock cdi for insurance.

The dyno I normally work with broke and they're taking forever to repair or replace it. So I'm looking for a new one.

cuong-nutz,

Who's Harry?

[Racer x]

What pistons are you using?
After the first break down. What did you do about the crank and did you replace the rod bolts?

[Swann]

JE and Yes. I replaced the conrod and the rod bolts too.

[Swann]

I found the little bastard giving me all the headaches for the past 7 months!!!

For the record, it was "Oil Starvation", exactly what we thought and the CULPRIT was the Magnetic Drain Plug!

I have magnetic drain plugs installed in my bike, which is effective, but had an unexpected side effect. Unfortunately the drain plug is made of an aluminum alloy, which expands when heated, allowing the force fitted magnet to come loose.

The magnet made it up all the way to a steel lined inlet just before the oil pump and partially blocked it. The oil was still able to flow, but not efficiently at high engine speeds.

Which explained why the engine ran properly at low RPMs and started going nutty every time I rode the bike above 11,000 rpm.

MYSTERY SOLVED!

PS. it took too long to figure it out and cost Conrods, a crankshaft, an exhaust valve, 3 sets of gaskets and Babit bearings to do it.

[micoulisninja]

Originally Posted by Swann

I found the little bastard giving me all the headaches for the past 7 months!!!

For the record, it was "Oil Starvation", exactly what we thought and the CULPRIT was the Magnetic Drain Plug!

I have magnetic drain plugs installed in my bike, which is effective, but had an unexpected side effect. Unfortunately the drain plug is made of an aluminum alloy, which expands when heated, allowing the force fitted magnet to come loose.

The magnet made it up all the way to a steel lined inlet just before the oil pump and partially blocked it. The oil was still able to flow, but not efficiently at high engine speeds.

Which explained why the engine ran properly at low RPMs and started going nutty every time I rode the bike above 11,000 rpm.

MYSTERY SOLVED!

PS. it took too long to figure it out and cost Conrods, a crankshaft, an exhaust valve, 3 sets of gaskets and Babit bearings to do it.

such huge damage by such a tiny part... at least you know what caused it and that it will not happen again -at least not because of that...
how did you find it ? must have taken every single thing apart...

[Somchai]

Hi Swann good to see you solved the problem

[Racer x]

That is just messed up. I hate to see things like this. It's like being injured by a safety device.

[Alex]

Good find.

[Swann]

Thanks guys, I feel rejuvenated that my bike is back to normal and I'm picking it up today.

I hope to ride it this Sunday.

[dcj13]

Originally Posted by Swann

...the CULPRIT was the Magnetic Drain Plug!

...magnetic drain plugs installed in my bike...Unfortunately the drain plug is made of an aluminum alloy, which expands when heated, allowing the force fitted magnet to come loose.

The magnet made it up all the way to a steel lined inlet just before the oil pump and partially blocked it...

Wow! Up to now, I've been a fan of magnets for capturing debris in the oil. The irony of it all...

Really appreciate you sharing this saga! I'm gonna remember this lesson: one best learned vicariously.

[Racer x]

The oil under pressure should lift the metal parts away from each other. There should not be metal stuff floating around that a magnet will catch. The filter will catch anything if there was some break in metal. changing the oil is the best bet. Bearings are made of non magnetic metals. So are Pistons. But after seeing this. At least check that the magnet is tight in the drain plug.

[Swann]

What I found strange, was there is a BYPASS inlet to the oil filter. The only thing that made sense was its was a guarantee that there would always be some oil flow regardless if the filter was clogged.


RacerX,

Aren't Babit bearings ferrous and magnetic?

You'll see in the attached picture, there are metal fragments attached to the magnet.

[Swann]

dcj13,

I was in despair about the breakdowns, fellow racers and buddies were saying I should replace the bike instead of struggling with it. They say it was cursed.

It came to the point I was already thinking about getting a 2015 250.

But I don't believe in evil spirits or get the heebeegeebies. I had to know WHY?

There is a reason to why it was happening and the main reason for the repeat failures, was we (me and the mechanic) were lazy.

We should have properly torn the engine apart after the first time and not just casually shrug, while replacing the bearings. That would have prevented all additional expenses and the complete waste 7 months and 2 races.

Modified engines and LAZY do not mix.

[Racer x]

The bearing shells are steel. The abbot is a this coat of lead like metal on top of copper. If you got through to the steel it's to late