Check This Out

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phillyskip

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Sep 15, 2013
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So I'm out riding my Commando up in Sussex County NJ with my pals. My bike is running great. With about a 1/4 mile to go before getting back to the garage my bike starts back firing,popping and making scary noises before she stops. We get the bike back to the shop and after removing the valve covers I discover I've got a "stuck valve". I trailer the bike back to Philly and take the head off. I use a single Mikuni.The manifold has 4 fasteners two on the outside ,two inside. One of the inside cap screws came loose and found a home stuck in valve seat. I bent the valve and the push rod. There was no other damage.Check This Out:....

http://i136.photobucket.com/albums/q166 ... 29597c.jpg
 
CanukNortonNut said:
you should have been running Amals...Mk1's
get your Loctite out.
not the first time.
Thomas
CNN
Click to expand...
Now I realize this is going to open up a whole can of worms :twisted:
 
Been there done that, mine stayed on top of the valve and rattled around the valve guide.
Ran as lean as due to the threaded hole where the screw was letting in lots of air.
Mine didn't bend the valve but that was sheer luck.

When you put the internal screws back in don't use any washers and prime thread (or not) and use locktite.

Your are not the first nor the last one to have this happen.

Cheers
Peter R
 
Loctite and I've already drilled the cap screws for safety wire! Regarding Amals ....Not for me....:)
 
Where did you drill the holes for the safety wire?
I hope you don't have a path to the outside atmosphere from the inside of the manifold by drilling the holes.
The cap screws are fairly recessed into the manifold to keep them out of the air/fuel stream to prevent any turbulence.
Locktite should do the trick (well it did for me)

Picture perhaps of what you have done?

Cheers
Peter
 
Blue locktite is the ticket for the two center bolts on a single carb manifold. Without something to retain them they will always fall out. jim
 
hobot caught Peel's Miki manifold bolts in time. I soon found out I hate resistance of loctite in such close quarters so another place that Nortons taught me to ignore torque wrench, as they scare ya too much. I anti seize mine but don't recommend anyone else does. If ya do trust t-wrenches instead of lockite I'd use a dab of your favorite color & smell RTV. Only spring pressure rattling on the bolt so maybe only have to get another bolt or dual carbs manifolds like Norton intended.
 
comnoz said:
Blue locktite is the ticket for the two center bolts on a single carb manifold. Without something to retain them they will always fall out. jim
Click to expand...

When I was reading about fitting single mik last year it came up a few times in this forum about the dangers of not loctiting the two center cap screws in place.

J
 
phillyskip said:
So I'm out riding my Commando up in Sussex County NJ with my pals. My bike is running great. With about a 1/4 mile to go before getting back to the garage my bike starts back firing,popping and making scary noises before she stops. We get the bike back to the shop and after removing the valve covers I discover I've got a "stuck valve". I trailer the bike back to Philly and take the head off. I use a single Mikuni.The manifold has 4 fasteners two on the outside ,two inside. One of the inside cap screws came loose and found a home stuck in valve seat. I bent the valve and the push rod. There was no other damage.Check This Out:....

http://i136.photobucket.com/albums/q166 ... 29597c.jpg
Click to expand...
Known pattern failure.
 
I drilled the holes for the safety wire in the top of the cap screws so no worry about air leakage. I will use the blue locktite as well. Funny ,I had two manifolds to choose from one with only two outer screws holding the manifold ,and the one with four. Thinking four was better, I choose it. BTW when I was taking the head of I discovered that all of my head steady screws were loose as well.....Skip
 
Check valve guide real well for a crack where it protrudes into the intake port also.

Russ
 
Interesting. I just pulled my manifold off the other day and while I was doing it the thought crossed my mind that it would be real interesting if these screws fell out. This is the first I have heard about this happening but I use blue loctite on all my fasteners anyway.
 
Yup, happened to me too. Didn't do any damage though. Locktite works.
 
surprised you didn't notice a change in how the bike ran from manifold leaks developing as they let loose - unless they let loose in one catastrophic minute - bummer regardless, but at least you get a fresh top end
 
I'm glad it wasn't worse either! I'm waiting on one new valve and a new flame ring head gasket. I'll have her back together in no time.
 
To "All" I must have missed the posts about these center manifold bolts loosening and not using blue locktite. Thanks to all for the reminder.
To Hobot,( my Norton Brother) Had I built my bike the way Norton intended I'd still have the horn under the battery carrier,points would be in the timing chest,the front forks would be "clunking away" over curbs,and I'd have two (not one) gas leaking Amals driving my wife nuts with fumes coming up from the shop. Furthermore my bike would still be positive "earthed".
It's pretty clear I'm no "purist" and just want to ride my Norton with a minimal amount of fuss.....Peace,PhillySkip
 
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