Blew a gasket looks like

speirmoor · Mar 20, 2012

Zipping along only about a mile from home it happened.At first I thought a Harley with open pipes had caught up to me and after glancing around the BQE looking for the offender i realized it was my machine that was making the Helicopter noise.Ok I thought exhaust leak probably but no when I hit a hill I noticed the drop in power.Limped home from the few last traffic lights with that one cylinder feeling.

[video]http://www.youtube.com/watch?v=xTkKphJP0Mg[/video]

Hobot · Mar 20, 2012

Ah man spierman you lucked out it was a wide section failure not more focused through the oil drain weak spot, in which case instead of mostly contained flames it jets straight out past and eventaully through the fuel hose right there. Next time pull over and make sure, I almost didn't in time, by the skin of my chinny chin chin thinned softened hose.

speirmoor · Mar 21, 2012

Didnt think of that Hobot I guess it couldve been worse.
Now my question is what caused this?
Never heard of it before last night.Almost 10K mi and the motor has never been opened.

L.A.B. · Mar 21, 2012

speirmoor said:
Now my question is what caused this?
Never heard of it before last night.Almost 10K mi and the motor has never been opened.

When was the last time you checked the head nut/bolt torque?

speirmoor · Mar 21, 2012

I must admit I've never done it LAB.I thought that was only for rebuilds only.Lesson learned the hard way will pay more attention after this repair.

john robert bould · Mar 22, 2012

It's a balance, Bolting a lump of alloy to a lump of cast iron,then heating it [un-evenly] will put strain on the bolts.
Depending upon how tight in the cold state,will give a cold clamping force,without over straining the assembly when hot.
The head gasket will compress a bit,causing the bolts to "loose" there grip on the gasket,period re-torque ensure the pressure on the gasket remains tight enough to keep in those gase's. hot and cold ..but avoid over tightening as the bolts will pass their elastic limits.
It's the invention of water cooling that cured all this. :lol:

YING · Mar 22, 2012

I have never seen anything on checking head bolt torque as something that should be checked.I understand that it should be
done after initial break-in,but was unaware that I should be checking it after that.Any guidence would be appreciated.
Thanks,
YING

comnoz · Mar 22, 2012

YING said:
I have never seen anything on checking head bolt torque as something that should be checked.I understand that it should be
done after initial break-in,but was unaware that I should be checking it after that.Any guidence would be appreciated.
Thanks,
YING

I tell my customers 6 times when new starting after the first heat cycle and increasing intervals when using a flame ring gasket. After that they should be re-torqued anytime the valves are adjusted or a minimum of once a year.

About the only time Commandos blow head gaskets is if the bolts come loose or a stud pulls. I normally re-tap the three stud holes for a 3/8 inch coarse threat helicoil insert. Then I install studs from ARP which are coarse on one end and fine on the other. Then I can use an ARP 12 point nut which only uses a 7/16 wrench on the rear stud. No more clearance issues. I install 3/8 inch fine thread helicoil inserts in the long nuts for the two front studs.

I do this before I use any head- even a brand new Fullauto.

The coarse thread helicoils hold much better in the aluminum head than fine thread. If British helicoils are used to repair the stud holes they will eventually fail again. The 3/8 coarse helicoils will hold very well as long as the head has not been overheated by welding. Jim

cjandme · Mar 22, 2012

speirmoor sorry for your problems, but that is a cool video, thanks for posting it. Cj

speirmoor · Mar 22, 2012

True the Bike wasnt ridden more than 1500mi last year but It was probably the most it was ridden in any one of its 36 years since it has less than 10Kmi on it.Sold 2 bikes this summer so this has been my go to bike more and more . I'm glad this happened now than on the road to Vermont later this year.
Good news is I got it started yesterday with some loud popping and mild explosions but pulled the sparkplug lead off and took off to the Bike shop.Meandered my way there though the back streets of Queens I made it on one cylinder.Puzzled guys at the shop when pulling in but it seems it happens and they all had similar tales of gasket failure.

Hobot · Mar 22, 2012

speirmoor glad to hear you collecting the trials and tribulations of Commandos to let you know they are not mere road appliances. I've had to put on some miles of a Cdo as a thumber plus my ole P!! too. They don't do too bad that way do they : )
Hehe any one notice the rust in the fins of the oil tight head shown. I admit though a mere dust mote on a clever made and tight ship. Are you going to take it back to the shop to re-torque after the first few heat cycles then at a few 100 miles etc?

Oh yeah, hope you didn't ride so far with ignited flame it jet cutted into the head. I bought a std head that way that turned out to be the key to Peels past spunk - I 'fixed' it temporary for a few seasons with just JBWeld razor'd-filed flush. Make sure shop knows to check for this.

batrider · Mar 27, 2012

What's happening with this? Is it gonna live?

pete.v · Mar 27, 2012

hobot said:
Hehe any one notice the rust in the fins of the oil tight head shown.

That's an interesting point. Non runners seem to be sooo rusty, where as a runner..........well, not so.

It also begs the question, was this head tight or just a non runner?

Hobot · Mar 27, 2012

Excuse me dear sir but these are Norton Commando's, so they can and do develop rust across the scope of conditions, stored still too long or run too long oil tight so nil protective weeps and mist any more. Ms Peel rusted on the barrel treads showing beyond her bright SS nuts. I've taken to cleaning around fasteners and sprizing with clear wheel paint. Any factory fasteners I've wire brushed bright tend to rust all the faster. I can't avoid condensation, water crossing or tall wet grass.

pete.v · Mar 27, 2012

hobot said:
Excuse me dear sir but these are Norton Commando's, so they can and do develop rust across the scope of conditions, stored still too long or run too long oil tight so nil protective weeps and mist any more. Ms Peel rusted on the barrel treads showing beyond her bright SS nuts. I've taken to cleaning around fasteners and sprizing with clear wheel paint. Any factory fasteners I've wire brushed bright tend to rust all the faster. I can't avoid condensation, water crossing or tall wet grass.

You are exceptional....or at least an exception. Maybe both....you choose.

Hobot · Mar 27, 2012

We are all an exception to the rules, w/o exception! There is some old fart peace in being mostly ordinary normal most the time even for me.

I'd heard prior funny stories of rusting fasteners once oil tight then saw it myself to get point of their humor too. Ugh, my buddy Wesley faces even worse wet and grime and muddy ruts and grass than I do. He trimmed his rear fender back last season and last time I saw him he mentioned it leaving a real cafe racers' mud stripe up his back side. Too vain to put on mud flaps but I sure ain't even on my 'exceptional' Peel.

Back on subject I'll try the steel foil type flamering Fair Spares an Anover vendor sent me and torque and torque until it or I blow out again, then will try no gasket for a time, then back to copper and re-doing it time to time. My main decision now it to place it dry or use metalic paint or copper coat or Hyolmar and cotton or silk thread.

speirmoor · Mar 29, 2012

batrider said:
What's happening with this? Is it gonna live?

When I dropped off the bike for repair I told my mechanic that there was more oil on the garage floor than usual and to check it out.He calls me up yesterday and says the oil tank has a a crack in it and thats the source of the extra oil.Luckily I scored an oiltank on fleabay last year so I dropped it off and hes going to throw it in.My garage buddy is a welder so he can repair the old one at his convenience as he loves projects of this nature.
The good news is that the gasket has been replaced with a copper one.All internals looks great he says.
Even better news is that the Boyer is coming out (tired of the kickback) and we're going back to regular ignition.He says he has one on hand so try it out.I was contemplating TriSpark but going to see how the original setup works.

cjandme · Mar 29, 2012

Hey speirmoor glad your motor is healthy again. Isn't kickback one of the problems with the original points/coil set up??----------"the Boyer is coming out (tired of the kickback)"-----I'm looking at the Oldbritts package deal 'cause it says that it also fires the plugs 3 times during startup and low RPM, and it comes with everything. I gotta protect that darn sprag clutch on my MKIII right?? Cj

DogT · Mar 29, 2012

Hey Spier,

If you want to use your old AAU, I'd suggest you get it bushed between the cam and the shaft like this.

Some European guy sent this pic a while ago and says he has been using his AAU ever since. Mine wore out so bad I could not get a consistent strobe within about 5 degrees in only 13K miles. If I could find someone to bush mine, I would, but the machinists around here are so expensive. I know hobot was interested in getting a bunch of them converted, but no one would send him all their worn AAUs. I think he even changed the cam profile too.

Dave
69S

bwolfie · Mar 29, 2012

If you are having your old tank repaired make sure to do the CNW reinforcement mod to it. I did mine myself while I had it out. It's not that much extra to do and saves a future headache. It's mostly strengthening the two upper attach points at the tank and reinforcment on the bottom.

Blew a gasket looks like

speirmoor

Hobot

speirmoor

L.A.B.

Moderator

speirmoor

john robert bould

YING

Pittsboro,NC

comnoz

cjandme

speirmoor

Hobot

batrider

pete.v

Hobot

pete.v

Hobot

speirmoor

cjandme

DogT

bwolfie

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