Oh my, this happened

The Trimetallic shells are typically overlay plated with a few microns of Lead/Indium or Lead/Tin that will disappear at the first sign of trouble. Below that is Leaded Bronze overlay over steel, as soon as that appears the shell needs to be renewed. There are no shell bearings anywhere that use copper alone as a layer, its typically alloyed with Tin or Aluminium plus other metals, leaded bronze being copper/tin and lead. There are now lead free versions due to environmental car end of life. This does not apply to aftermarket so Norton Trimetallic shells are leaded bronze.

I am sure Lucas know how to make oil but conditions can vary and one oil will cavitate under conditions that others don't.

I'm screwed then. Have to find a good crank person (Marine Crankshafts most likely) and get the crank resized or polished if possible. I'm way past the time I should have torn the engine apart given the look of the oil, which looked similar last time I changed oil and filter about 400 miles ago. Crank will have to be ground -.010 most likely. Oh well. That's what I get for using an oil gauge with a skinny 1/8" line.

And yes I know everyone else with an oil gauge that uses 1/8" lines has never had a problem.

Pulling the engine is an opportunity to do the engine plates to support the TTi gearbox using the short P11 primary as two one sheet plates instead of how I prototyped it. Might also make a set for a racey longer primary so I can move the gearbox back. Big maybe however.

A crank journal on std size should still have any hardness process from new in place so you may be lucky and only the shells have been affected. Not sure if any hardness process was applied by the factory but aftermarket nitriding of the journals will typically double journal life.

kommando said:

A crank journal on std size should still have any hardness process from new in place so you may be lucky and only the shells have been affected. Not sure if any hardness process was applied by the factory but aftermarket nitriding of the journals will typically double journal life.

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That would be the perfect fantasy scenario. Journals on the Molnar crank I bought were not nitrided.

There is one more reason too embarrassing to mention as to why the big end shells are toast. Not bubbles related. High stupidity was in play on the very first start of the engine after I put it together. I should have torn it down the very next day. That is how stupid it was. I thought maybe I'd get lucky and kept on running it. Didn't work out since there's really no such thing as luck to correct mistakes with machinery.

Other thought: The bubbles could be partially related to turning the oil junction block over with the tubes pointing down so I could get the feed and return hoses under the TTi gearbox. There was not room between the timing chest and gearbox to go over the top. Considering how far from stock the P11 is now I should have cut the primary and made it 1/2" longer. Then I could have moved the gearbox back and run the oil hoses over the top. I may do that if I can make it work. Bike is going in the corner for a while. I have other fish to fry.

The wife is rolling her eyes and saying you should get rid of that thing. She's probably right, but a man has to have his enthusiasms.

As this has happened over a short period running wise then the softer bearing material should been the one affected over the journal. The wearing out of the harder material in a journal/bearing is when the softer material has absorbed all the hard particles it can. These hard particles then stick to the bearing surface like sand to sandpaper and wear out the journal. In bearing speak the ability to absorb particles/debris is called embedability and leaded bronze is good in that respect. If you fit a filter then you can go for harder bearing materials with less embedability such as Aluminium/Tin.

Schwany said:

There is one more reason too embarrassing to mention as to why the big end shells are toast. Not bubbles related. High stupidity was in play on the very first start of the engine after I put it together. I should have torn it down the very next day. That is how stupid it was. I thought maybe I'd get lucky and kept on running it. Didn't work out since there's really no such thing as luck to correct mistakes with machinery.


The wife is rolling her eyes and saying you should get rid of that thing. She's probably right, but a man has to have his enthusiasms.

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Most people don't know better and they do the wrong thing without knowing they are just taking a chance. At least you know better, and took that chance. I did the same thing on my last rebuild. I'm not going to be surprised if my cam and followers don't last very long.

Edited to add: I also keep an eye on my oil when I change it for metallic content, because like you I knew better...

My Italian grandma was a wise lady who couldn't read or write, except to sign her name. She spoke broken english, sometimes in half sentences, but she always said enough that you knew what she meant. One of her favorite sayings was: "If Columbus never took a chance...."

As far as your wife telling you to give up, you can see from my quote below my post, I've been dealing with that attitude my entire life... Thankfully I never gave in and gave up!

kommando said:

As this has happened over a short period running wise then the softer bearing material should been the one affected over the journal. The wearing out of the harder material in a journal/bearing is when the softer material has absorbed all the hard particles it can. These hard particles then stick to the bearing surface like sand to sandpaper and wear out the journal. In bearing speak the ability to absorb particles/debris is called embedability and leaded bronze is good in that respect. If you fit a filter then you can go for harder bearing materials with less embedability such as Aluminium/Tin.

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My spin-on filter lets the powdery bronze through, so it is relatively small. Still abrasive though I would imagine. I do not have a clue of course whether or not the remaining material on the bearings has metal chunks in it. I think probably not, but that could be overly optimistic.

MAP does not include bearing composition information in the product description unfortunately. I'd have to send an email or call. All they say is finest materials available made in the USA.

o0norton0o said:

Most people don't know better and they do the wrong thing without knowing they are just taking a chance. At least you know better, and took that chance. I did the same thing on my last rebuild. I'm not going to be surprised if my cam and followers don't last very long.

Edited to add: I also keep an eye on my oil when I change it for metallic content, because like you I knew better...

My Italian grandma was a wise lady who couldn't read or write, except to sign her name. She spoke broken english, sometimes in half sentences, but she always said enough that you knew what she meant. One of her favorite sayings was: "If Columbus never took a chance...."

As far as your wife telling you to give up, you can see from my quote below my post, I've been dealing with that attitude my entire life... Thankfully I never gave in and gave up!

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Assembly was all clean and as good as I ever get not being excessively anal. I tend to trust the people I buy parts from know what they are doing, which may or may not be all that smart. Lubrication first start after the rebuild is a different story. Big dumb move due to my childish excitement of wanting to start the engine.

Schwany said:

All they say is finest materials available made in the USA.

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That will be Clevite 77 then, the base material is made in McConnelsville Ohio and then machined and plated in Atlantic Iowa. Could be plated with a lead/tin or lead/indium, too long ago to be sure.

The short-stroke engine in my 500cc Triton used to rev above 10,000 RPM and was always losing oil pressure. I had the crank reground then took it to the Ordnance factory where I worked and had the journals hard chromium plated. I then went to a friendly supplier of car bearings. The guy there did some research and found that Mini-Cooper fit the Triumph 650 rods, but with a thou extra crush - they are made of hard grade of copper-lead. After I had the chromium ground and fitted those bearings -after racing, the pressure indicator button used to stay out for a very long time. I have never worried about oil pressure with my Commando motor - it only revs to 7000 RPM and was not raced very often. I sometimes wonder about the gear-type oil pump. I think a plunger pump is better.
Matt Spencer has claimed the top part of the Triumph 650 oil indicator and pressure relief valve fits the bottom part of the Commando pressure relief valve - same thread.

Schwany said:

I'm screwed then. Have to find a good crank person (Marine Crankshafts most likely) and get the crank resized or polished if possible. I'm way past the time I should have torn the engine apart given the look of the oil, which looked similar last time I changed oil and filter about 400 miles ago. Crank will have to be ground -.010 most likely. Oh well. That's what I get for using an oil gauge with a skinny 1/8" line.

And yes I know everyone else with an oil gauge that uses 1/8" lines has never had a problem.

Pulling the engine is an opportunity to do the engine plates to support the TTi gearbox using the short P11 primary as two one sheet plates instead of how I prototyped it. Might also make a set for a racey longer primary so I can move the gearbox back. Big maybe however.

Click to expand...

I had mine done at Marine, and they did a nice job. It was .010. Lucky for me they are only a 20 minute drive, so no shipping. It was during the pandemic and took ages, as did the head that I had done up the road at Q&E.

gpzkat said:

I had mine done at Marine, and they did a nice job. It was .010. Lucky for me they are only a 20 minute drive, so no shipping. It was during the pandemic and took ages, as did the head that I had done up the road at Q&E.

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Damage might not be bad. Engine is only noisy at idle, but it's the wrong kind of noise and I did wait a long time to do anything about it.

Yeah the shipping part does not thrill me much. Things can happen during shipping, and even a lighter crank is a clunky heavy item.

Q&E prices look too reasonable. Must be an old price list. My head could use new guides. I could get it done locally, but it would be two months before I see the head again. Even longer if I sent it to Mr C. I have a spare Commando head, but it's stock. Not that sure I want to use it. I'd be in for a lot of tuning and testing. First world problems.

Lots to think about. I have not started yet. House and garage painting is a priority while the sun is shinning, cuz it does not shine long up here.

Schwany said:

Journals on the Molnar crank I bought were not nitrided.

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Really? Crankshaft journals are typically nitrided, tuftrided, or induction hardened. The chosen method depends on choice of steel. I find it hard to believe Molnar did not provide some sort of surface hardening.

- Knut

Schwany said:

My head could use new guides. I could get it done locally, but it would be two months before I see the head again. Even longer if I sent it to Mr C.

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Make sure you order oversize valve guides. Most valve guides marketed are for first time replacement only. Subsequent replacements require broaching and use of oversize guides. Reason is, the replacement process inevitably removes some of the soft aluminum despite heating, which leads to a poor thermal fit (guides may drop) and also poorer thermal heat flow when using standard size guides. I was reminded of this fact by Seager Engineering this spring. He makes all valve guides in-house to ensure a proper fit. AN offers oversize guides for their bronze guides only (see section "Go Faster Stuff").

- Knut

mdt-son said:

Really? Crankshaft journals are typically nitrided, tuftrided, or induction hardened. The chosen method depends on choice of steel. I find it hard to believe Molnar did not provide some sort of surface hardening.

- Knut

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He probably did harden the journals, but how isn't in the description. Rather than respond with my uneducated babble, I should stick to just handing out thumbs up when comments show up in threads I start.

Schwany said:

I was running the timed breather and a breather off the back of the timing case on my altered P11 engine. Tried to hit 100MPH on a previous ride which shouldn't be an issue and ran into a wall at 93MPH. Engine went limp like the cam went flat at 93MPH. That is not what happened, so don't dwell on it. I removed the plumbing and plugged the time breather port, and now the JS2 cam and engine comes to life like it used to. Unfortunately, on my test run I forgot that Hwy 5 was closed Northbound into Seattle. I hit 70 in 3rd (5 speed TTi box) the engine exhaust note started singing and farts wouldn't you know it I came up on a long assed line of stop and go traffic 4 lanes wide Northbound. Was trapped in it for half an hour. Will try again Wednesday but in the other direction. lol

There is a point in there and it is running both a standard timed breather and a reed valve breather on the back of the timing case does not work well at high RPM on "my" engine. I know who is going to say but I never have a problem with that set up. If that is true, have you done 100 MPH and beyond with both breathers attached? My goal is 120MPH by the way. Should be exciting to see if it stays stable. Yeehaw.

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120 on a P11 sounds impossible without some SERIOUS engine work, and re-gearing the final drive ratio.

grandpaul said:

120 on a P11 sounds impossible without some SERIOUS engine work, and re-gearing the final drive ratio.

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It's a long way from stock. Higher gearing in the primary and the final drive along with engine work has been done. 108 with stock gearing and less engine work in the 90's. 120 is possible, but of course without a video it'll be really difficult to prove it happened if it does ever happen. I might have to get a little action camera.

I'm tearing the engine down to find out where the bronze in the oil is coming from, so my fantasy speed test is not going to happen anytime soon.

Schwany said:

It's a long way from stock. Higher gearing in the primary and the final drive along with engine work has been done. 108 with stock gearing and less engine work in the 90's. 120 is possible, but of course without a video it'll be really difficult to prove it happened if it does ever happen. I might have to get a little action camera.

I'm tearing the engine down to find out where the bronze in the oil is coming from, so my fantasy speed test is not going to happen anytime soon.

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I'd say 120 would be easily possible with your setup
I can't see anything on your build that's lacking
Fingers crossed that the damage isn't too bad
Maybe even a clean up and new shells

I thought I saw bronze lifter guides you had posted a while back...

concours said:

I thought I saw bronze lifter guides you had posted a while back...

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Would that be the mod that uses BSA lifters and beehive springs, etc?