I think I got the goody out of that one.

comnoz · Oct 19, 2013

So the teardown begins

I think I got the goody out of that one.

So far so good, no smashed plugs

That piston looks a little strange

The left intake valve is seriously bent and the right is slightly bent.

I think that piston is pretty well used up

Cam looks great

The lifters look good but sleeves will be needed

Really looks pretty good considering I rode it 35 miles after the piston broke. Jim

1up3down · Oct 19, 2013

Gruesome

what could have caused this to happen Jim?

Powereng03 · Oct 19, 2013

So what are the benefits of running the domed piston on 1 side and not both??? Nasty looking.

comnoz · Oct 19, 2013

1up3down said:
Gruesome

what could have caused this to happen Jim?

I got some low octane fuel from a premium pump in Northern Texas on the way to the LOP rally. It was a hot day and I was riding with my visor open and earplugs so I didn't hear the engine pinging until the left side piston seized. It happened as I topped the second hill from the gas station. I pulled the clutch immediately and coasted down the other side and restarted the motor before I came to a stop. It ran fine but had a tapping noise at idle from the piston damage.
As soon as I applied any load the engine pinged heavily like it was running on regular fuel. I babied it into the next town and got some octane booster which cured the pinging but there was obviously damage to the piston. I rode it over 3000 miles after the seizure - on to LOP and Barbers. The rapping at idle got a little louder for the next 1000 miles and then after that it didn't change any more. At road speed the engine ran fine and no noise was audible. The oil consumption increased from 1 pint per 1000 miles to 1 quart per 1000 miles. Power was normal.

Then 180 miles from home the piston broke. The noise got very loud and I lost all compression on the left and most of the compression on the right. I limped 35 miles back into the nearest town at it's maximum speed of 30 MPH on one cylinder. The noise was getting louder all the way and when I reached town it stopped running for good. Jim

Hobot · Oct 19, 2013

Disgustingly impressive Jim, so your nerve wracking riding images all those miles were right on, ugh. I assume the piston finally beat itself up to rock so much the intake valve struck it to bend? Did ya have an oil pump protective screen installed? Will the rod with the beater on top still be usable as is or needs exam now? Would the crank bearings expect to be beaten to replace by this? [besides just plain long mileage] All from undetected till too late detonation eh, hmm.

BitchinBeezer · Oct 19, 2013

comnoz said:
So the teardown begins

Are those injectors I see on the intake manifold?

swooshdave · Oct 19, 2013

comnoz said:
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Any chance you'd be willing to donate that piston to make a trophy for the rally next year, assuming it doesn't go on your shelf? :mrgreen:

CanukNortonNut · Oct 19, 2013

Wow Jim,
That is one seriously pooched piston. :shock: Maybe you should have hitched a ride with CNW back home with the trailer.
I bet the bike told you it was hurtin near the end. Nothing you can't fix.
I would check your oil filter and pump for bits just for S%#!s and Giggles. BTW what pistons were you using with the steel rods?
Regards,
Thomas
CNN

cjandme · Oct 19, 2013

comnoz said:
I think that piston is pretty well used up,
. Jim

but maybe like swoosh says , it could be used as a trophy, that way you could get some more miles out of it. thanks for the photos, it is quite remarkable that you were able to take it as far as you did.

Big_Jim59 · Oct 19, 2013

Judging by the pictures of the bottom-end your robust crank and rod assemble contributed mightily to your "good fortune" scenario. That piston is just nasty but that rods are amazing.

comnoz · Oct 19, 2013

Yeah the rods looked good but after carefully removing the piston I noticed the oil hole in the bushing was not lined up. I pushed the bushing out with my finger. It will be going back to Carrillo for a refresh. Jim

motorson · Oct 19, 2013

Awe. That little piston just wanted to turn around and come down the same way it went up! You should send photos to the gas station where you got the fuel. I bet you still have the receipt and everything.

comsteg · Oct 19, 2013

Oh come on Bro! You have way more piston left than I did on my second attempt to get past Borger, Texas!

comnoz · Oct 19, 2013

comsteg said:
Oh come on Bro! You have way more piston left than I did on my second attempt to get past Borger, Texas!

Heh, Makes me glad I had forged pistons. I could have been going home on a trailer early like you did.
Better get ready for next year. Then Alaska in May 2016!

comnoz · Oct 19, 2013

BitchinBeezer said:
comnoz said:

So the teardown begins

Click to expand...

Are those injectors I see on the intake manifold?

Yes

comsteg · Oct 19, 2013

This is what happens when you schedule a nice long vacation and attempt to chase your big brother across Texas to LOP and on to Barber. This is the first attempt, seriously doubt it had anything to do with the bad gas. This half the case had taken a nice broken rod hit over 10 years ago.

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Got the bike back home, installed a second engine I had on the shelf and headed out again. Made it 3 miles from the first attempt and the engine started to rattle. Turned around and made it almost 300 miles before it gave its last. The rest of the piston was mostly fine crumbles in the bottom of the case, except for a big piece that prevented the crank from doing its job.

[/URL][/img]

comnoz · Oct 20, 2013

CanukNortonNut said:
Wow Jim,
That is one seriously pooched piston. :shock: Maybe you should have hitched a ride with CNW back home with the trailer.
I bet the bike told you it was hurtin near the end. Nothing you can't fix.
I would check your oil filter and pump for bits just for S%#!s and Giggles. BTW what pistons were you using with the steel rods?
Regards,
Thomas
CNN

Actually the bike ran great right up till the piston broke.
It was pretty noisy at idle especially when cold after the seizure. I was actually kind of surprised it ran as long as it did.

They were forged Venolia's I got from TC back in the 80's. Heavy but tough. Jim

acotrel · Oct 20, 2013

Same question - is the motor fuel injected ? Why didn't the EMS detect the pinging and adjust for it ?

BitchinBeezer · Oct 20, 2013

comnoz said:
BitchinBeezer said:

comnoz said:

So the teardown begins

Click to expand...

Are those injectors I see on the intake manifold?

Click to expand...

Yes

What seems strange to me, if it was a purely octane related failure, is that the other piston shows no signs of detonation whatsoever. Of course running the engine after the initial failure would have masked any evidence but I would still suspect that something was amiss only in the cylinder that failed.

I would suspect that A/F ratio might have been the culprit. A lean A/F ratio in that particular cylinder would have exacerbated an already marginal octane situation.

Have you checked the injectors for fuel delivery?

swooshdave · Oct 20, 2013

acotrel said:
Same question - is the motor fuel injected ? Why didn't the EMS detect the pinging and adjust for it ?

From what Jim said you can't put a knock sensor on a Norton. Too much noise at normal operation.

I think I got the goody out of that one.

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