I'm thinking this can't be good...

Please allow me to preface this post by saying that I planned on doing something with the motor in my '70 C'do this winter anyway.

This afternoon, I decide to take the Commando out for a little ride to go get coffee and stop by the local Honda dealer to get paint codes for something I'm working on. Anyway, I checked the oil, tire pressure, etc like I do every time I ride the C'do and all was fine. Oil flowed well to the tank and everything.

I go get myself some coffee and head for the Honda dealer. All goes fine at the dealer and I'm headed home. On the way, the bike hiccups and dies at a stoplight. No big deal, right? So I push it off the road and kick it a couple times. Everything seemed ok until it lit. When it lit, all hell broke loose; literally. You would swear the Marines were landing at Iwo Jima judging by the smoke coming out of the left exhaust and what sounded like a metal trash can full of ball bearings being shaken coming from the top end of the motor. I didn't let this go on long, obviously. I called the lovely wife to bring the truck and ramps so I can at least get home. Thankfully, she was off this afternoon and I was only about a mile from home so she wasn't really pissed.

I get the bike home.... Now the fun part...

I try to slowly and gently push the kicker through by hand to see if I felt anything. I have never been able to effortlessly do so, but this time was different... There is next to no compression. I then decide to drain the sump and see if there is anything there. Well, there was. From the sump, I got about 7 pieces of magnetic metal about the size of a .177 pellet. At least nothing from inside the motor found its way outside the motor in search of greener pastures and daylight.

Just thought I would share my joy of today.

I've been there, my condolances. Mine happened about a mile from home and I said screw it. When I arrived home it was still running, no smoke, but not sounding well. After I turned it off and tried to turn it over, it would only move a little then lock up. The bits of piston skirt were floating around while it was running, but lodged in after it stopped.
All tolled, pistons, rings, and a crank needed to be replaced among other small things. Not a good day.

I ended up buying a basket case with good parts and combined the good from both. Worked out well for me. I hope your's isn't as bad as mine.

Thanks for the condolences.

My next letter will begin:

Dear Santa...

Cam/lifter bits? Ring Matter? If you are lucky....I guess.

Sorry for your loss.
We'll be watching.

Peter

Sounds to me like a ball main bearing came apart. Jim

FUDGE .

Id be having a thick newspaper out , and whipping it down over that .Hopefully its not all bad .

Whip the rocker cover and see if its a jumped pushrod / rockers engaged , for starters .

All told,yes that motor has to come completely apart and inspected and oil tank /lines flushed clean etc. Sounds like winter came a tad early for you. Photos ?

Oh Ugh, hope no out of the blue minding your own business blow ups ever happens to mine. As engine still turns implies bottom end spared and valve might of stuck which holed piston and busted the lifter bores. Guessing of course w/o the pain of really finding out myself. Be super suspicious of every oil passage and port leaving the sump and pump. Someone I know said they knew someone that found the loosely inhaled swarf became locked deeply in place once coolly contracted around. Crank run out check up too. Have you been a good boy for Santa's list? Not if you have to steal stuff, like more time away from life's little naggers.

cha-ching $$$

look at the bright side - afterwards you'll have a motor that you know you can count on!

TURNIG IT isnt going to achive Anything Good . NOT Adviseable . Sounds like someting metalic/ steel is broken .Maybe a valve guide and/or rocker, amongst other things , unfortunately .

Pity about the restart . Live and Learn .We might get some intresting pictures out of it , anyway . Dont automatically assume the worst . Maye be confined to valve gear . ? :mrgreen:

I'll guess the top of your left piston came then collision with valves.
Hard to imagine valves breaking into tiny pieces though.
Pulling valve covers and turning motor slowly sounds like a good place to start.
Head off next will probably tell you a lot.
Maybe a days work.
Good luck. Just be glad it didn't ruin your summer riding. :?
Bob

Steel, cast iron or aluminum "bits"? During prtotype testing we had a final drive chain break while doing about 105 mph on the track. When we tore the engine down, it looked like the massive over-revving (the tach needle was bent back at the end) when the drive was disconnected with the throttle wide open had allowed the valves to float. Onece they weren't following the cam profile, they got clouted by the piston. That cracked the piston all the way down through the wrist-pin bearing to the bottom of the skirt.

This caused the piston to jam in the cylinder, so the con rod and wristpin tore down through the piston and out the bottom. When the rod got all the way to bdc, there was enough room for it to fall sideways and punch a hole in the crankcase. That motor made a good boat anchor!

Luckily, it was the catalyst for getting the top brass to finally recognise that we needed a huskier chain than 1/4". The Atlas had a 3/8" chain for ever. Why they thought 1/4" would be good enough, I still can't figure.

Let us know how you make out, sorry for your problems, I'm waiting for the hammer to drop on mine.

Dave
69S

Come to think of it if you have little bits stuck to magnetic sump plug it is just too late to fix anything really. Just tear apart the whole motor cleaning and inspecting for source of grief ,naturally. Should only take you one winter and a strong credit- cardy thing.New oil, filter, clean out oil tank sludge and split crank to clean out sludgetrap too .Oil pump inspection too. Buy a case of beer and a box of Kleenex (oops - product placement).

Anyone suggesting ' turn it ' should stick a finger in it , whilst doing so .

Come to think of it if you have little bits stuck to magnetic sump plug it is just too late to fix anything really.

Click to expand...

Not even from the magnetic sump. Chunks came out with the oil. I held a magnet to the pieces to see if it was aluminum or steel. It was magnetic...

chapmanmd said:

...(blow-up)...

Click to expand...

So many bikes and projects going on around here, did your bike have a recent history of overhaul or modification?

Just curious; post-mortems can be very educational.

I'll put money on the stelite tip on a cam follower (tappet) has come off. I had a similar pile of small bits in the sump on a Commando I bought last year. The tappets, cam, one piston and one rod were toast. Luckily it didn't mess up the cases or the barrels... although one bit lodged itself into the cam gallery. Oddly enough it was running okay but another five minutes and it probably would have imploded. Good luck !
Mick

moorejm said:

I'll put money on the stelite tip on a cam follower (tappet) has come off.

Click to expand...

I'd guess that's the best bet to put money on...

Thanks for the replies.

The PO of the bike claimed "recent rebuild". How much of that if any is true remains a mystery.

I didn't have a chance to pull anything apart over the weekend. I am a complete nOOb to Norton's, but somehow, I'll get through it.

Now I just need to make the decision as to whether I just say, "damned the torpedoes", dig into and learn as I go or just crate up the motor and send it to someone who can say this ain't their first rodeo and will do it right the first time. Don't get me wrong, I've rebuilt plenty of motors, but I've never been inside a Norton. I know that there is the personal satisfaction of having done it myself, but I can also make the argument that I would like to have the bike back on the road someday.

Look for yet another build thread coming to a theatre near you soon.

Thanks again all for the condolences and input. You guys, as always are the best.

Mark