My NC35 just died! High detail pictures. Help me out

[andreasmkr]

I noticed some abnormal sounds coming for the engine yesturday, so I decided to take it out to have a closer look and this is what I found!

Ony one of them has noticable marks on the inside of the shells, the others has "scuff" marks on the outside of the shells and on the conrods itself?




















Any ideas??? Do I need a new crankshaft & conrods?

[cajun]

I'd check both for spec. But it looks like you may have spun that bearing. Are the lines in them "feelable"? Like can you scratch them with your fingernail? If so you probably need new rods. But also check the crank.

The best way to tell is check them with Plastic guage. But yeah..... It doesn't look good. How are the faces of the valves?

And did it just stop running on you or make terrible sounds and all the sudden lost of power?

[riktrik79]

Hmmm doesn't look good.
I've seen lots of this on marine engines.
Bearing failure either from poor lubrication or particles in lube oil

Particles will cause scoring leading to the white metal becoming stripped preventing any type of oil wedge between the bearing shell and crankpin. this can cuase over heating, melting the rest of the white metal of the steel backing of shell. this shell could of spun in bottom end bearing shells.

What was your oil level like?
Have you done any engine work recently?
Is there any scorch marks on bottom ends?
Any signs of damage to cylinder liners?

at the least you'll need new bearing shells and con rod arrangement
If the crank shaft has scoring too, could need knew one of them too, i'm not sure on tolerances on crank pins on these tiny engines. on large engines its possible to grind and polish out problems while retaining shape, and then use oversized bearing shells.

I'd get on ebay for a secondhand engine, probably work out cheaper

[andreasmkr]

I'd check both for spec. But it looks like you may have spun that bearing. Are the lines in them "feelable"? Like can you scratch them with your fingernail? If so you probably need new rods. But also check the crank.

The best way to tell is check them with Plastic guage. But yeah..... It doesn't look good. How are the faces of the valves?

And did it just stop running on you or make terrible sounds and all the sudden lost of power?

The lines on the outside of the shells is not feelable and that includes the marks on the con-rods.
But the one with the deep scars is very feelable. I found t he scrapings from that bearing in the oil pump filter.

Valves looks good. No damage to them.

The sound cabe gradually and got worse and worse the longer i drove, same with the power.
I had to get it towed back not to ruin the whole engine.

The Crank is out of limits (checked with a micro-meter) One place where the con-rods connect to the crank is oval.... This is also whre I found the most damaged shell bearing ( damage on the inside of the shell ) Pic. 6.

[andreasmkr]

Hmmm doesn't look good.
I've seen lots of this on marine engines.
Bearing failure either from poor lubrication or particles in lube oil

Particles will cause scoring leading to the white metal becoming stripped preventing any type of oil wedge between the bearing shell and crankpin. this can cuase over heating, melting the rest of the white metal of the steel backing of shell. this shell could of spun in bottom end bearing shells.

What was your oil level like?
Have you done any engine work recently?
Is there any scorch marks on bottom ends?
Any signs of damage to cylinder liners?

at the least you'll need new bearing shells and con rod arrangement
If the crank shaft has scoring too, could need knew one of them too, i'm not sure on tolerances on crank pins on these tiny engines. on large engines its possible to grind and polish out problems while retaining shape, and then use oversized bearing shells.

I'd get on ebay for a secondhand engine, probably work out cheaper

The oil level where spot on. I recently did a service on the engine. New crank bearings, con-rod bearing, piston rings, oil, oil filter etc.. Wrong sized shell bearings maybe...?

And there is luckily no damage to the cylinder liners, they all look fine.

Probably ending up with a secound hand engine from Ebay, but the shipping is like 250£ to Norway + the the engine price.

[Neosophist]

The oil level where spot on. I recently did a service on the engine. New crank bearings, con-rod bearing, piston rings, oil, oil filter etc.. Wrong sized shell bearings maybe...?

Was the engine already worn or did you just replace them? Seems a pretty intense service. (most VFR engines will reliably go upto 70-80k km without needing rings or bearings providing they've had oil in them.

Interesting failure there.

How did you determine what bearing shells to order? (plastigauge?) and did you check them after-installing them... i've ordered bearing shells before only to find after installation that the ones supplied were infact wrong! (good job I double checked)

If they were correct perhaps there was a blockage in one of the oil passageways or oil filter, or even some particle contamination.

Did you flush out the engine before working on it? I've sometimes found with worn bearings to have metal contaminate in the engine, a good parrafin gun on a high pressure airline to blow through the entire block helps to remove any traces of material... you only need a few metal fragments to hit one of the jornals to cause wear.. this then creates more metal and you get a chain-reaction that eats up your internals.

Was the oil used new / clean and the correct grade?

Terrible shame but i'd get a good known running engine.

Have you tried speaking with Drew (Moriwaki Man) He lives out in Japan and can get you a decent known running engine if there arn't any easily available where you live

[Lane]

It normally takes catastrophic abuse to damage the cylinder walls on any engine that has Nikasil coated bores.

[cajun]

Hmmm doesn't look good.
I've seen lots of this on marine engines.
Bearing failure either from poor lubrication or particles in lube oil

Particles will cause scoring leading to the white metal becoming stripped preventing any type of oil wedge between the bearing shell and crankpin. this can cuase over heating, melting the rest of the white metal of the steel backing of shell. this shell could of spun in bottom end bearing shells.

What was your oil level like?
Have you done any engine work recently?
Is there any scorch marks on bottom ends?
Any signs of damage to cylinder liners?

at the least you'll need new bearing shells and con rod arrangement
If the crank shaft has scoring too, could need knew one of them too, i'm not sure on tolerances on crank pins on these tiny engines. on large engines its possible to grind and polish out problems while retaining shape, and then use oversized bearing shells.

I'd get on ebay for a secondhand engine, probably work out cheaper

The oil level where spot on. I recently did a service on the engine. New crank bearings, con-rod bearing, piston rings, oil, oil filter etc.. Wrong sized shell bearings maybe...?

And there is luckily no damage to the cylinder liners, they all look fine.

Probably ending up with a secound hand engine from Ebay, but the shipping is like 250£ to Norway + the the engine price.

Did You do the service or did you have someone do it for you? And I'm with Neo. Did you just order by the color codes by the crank and case? Every engine when rebuilt should be put together twice. Especially if it is a servicing of an engine. Take it all apart, clean it, put the current bearings back in, take a measurement with a Micrometer then recheck using plasiq guage then order the appropiate bearing. Then check it again when the correct bearings arrive by using the plasiq guage again. Ask me how I know all this.... hahahah

But (in a unrelated incident I swear) It actually looks like a 29 engine that I had let go on me and spun a bearing. The reason was, when the engine was refreshed, the rods and pistons were pulled out and numbered and placed on the side. Well they were numbered but the caps were not marked by these numbers, so a C1 cap went onto a C2 rod.... Lasted 5 races like that then ruined a crank.

[andreasmkr]

The oil level where spot on. I recently did a service on the engine. New crank bearings, con-rod bearing, piston rings, oil, oil filter etc.. Wrong sized shell bearings maybe...?

Was the engine already worn or did you just replace them? Seems a pretty intense service. (most VFR engines will reliably go upto 70-80k km without needing rings or bearings providing they've had oil in them.

Interesting failure there.

How did you determine what bearing shells to order? (plastigauge?) and did you check them after-installing them... i've ordered bearing shells before only to find after installation that the ones supplied were infact wrong! (good job I double checked)

If they were correct perhaps there was a blockage in one of the oil passageways or oil filter, or even some particle contamination.

Did you flush out the engine before working on it? I've sometimes found with worn bearings to have metal contaminate in the engine, a good parrafin gun on a high pressure airline to blow through the entire block helps to remove any traces of material... you only need a few metal fragments to hit one of the jornals to cause wear.. this then creates more metal and you get a chain-reaction that eats up your internals.

Was the oil used new / clean and the correct grade?

Terrible shame but i'd get a good known running engine.

Have you tried speaking with Drew (Moriwaki Man) He lives out in Japan and can get you a decent known running engine if there arn't any easily available where you live

I just replaced them to get a freshly serviced engine while I where restoring my bike. (stupid choice)

I determined the bearings with the crank &piston numbers. I where not thinking of measuring them with plastigauge at all :/ That's probably why the failure took place...

[andreasmkr]

Hmmm doesn't look good.
I've seen lots of this on marine engines.
Bearing failure either from poor lubrication or particles in lube oil

Particles will cause scoring leading to the white metal becoming stripped preventing any type of oil wedge between the bearing shell and crankpin. this can cuase over heating, melting the rest of the white metal of the steel backing of shell. this shell could of spun in bottom end bearing shells.

What was your oil level like?
Have you done any engine work recently?
Is there any scorch marks on bottom ends?
Any signs of damage to cylinder liners?

at the least you'll need new bearing shells and con rod arrangement
If the crank shaft has scoring too, could need knew one of them too, i'm not sure on tolerances on crank pins on these tiny engines. on large engines its possible to grind and polish out problems while retaining shape, and then use oversized bearing shells.

I'd get on ebay for a secondhand engine, probably work out cheaper

The oil level where spot on. I recently did a service on the engine. New crank bearings, con-rod bearing, piston rings, oil, oil filter etc.. Wrong sized shell bearings maybe...?

And there is luckily no damage to the cylinder liners, they all look fine.

Probably ending up with a secound hand engine from Ebay, but the shipping is like 250£ to Norway + the the engine price.

Did You do the service or did you have someone do it for you? And I'm with Neo. Did you just order by the color codes by the crank and case? Every engine when rebuilt should be put together twice. Especially if it is a servicing of an engine. Take it all apart, clean it, put the current bearings back in, take a measurement with a Micrometer then recheck using plasiq guage then order the appropiate bearing. Then check it again when the correct bearings arrive by using the plasiq guage again. Ask me how I know all this.... hahahah

But (in a unrelated incident I swear) It actually looks like a 29 engine that I had let go on me and spun a bearing. The reason was, when the engine was refreshed, the rods and pistons were pulled out and numbered and placed on the side. Well they were numbered but the caps were not marked by these numbers, so a C1 cap went onto a C2 rod.... Lasted 5 races like that then ruined a crank.

I did the service myself together with my father. (Oldtime mechanic)

About the caps... That's probably what happened to me aswel.. I did not think to match up all the caps with the con-rods. Lesson learned!