My carb fell off. Oof.

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With one screw falling out, the remaining would be placing more bending load on the bowl flange. Best to remove bowls and place on a known flat surface (a flat sheet of glass is good or stone counter tops etc). Check in all directions for any wobble against the sealing surface and flat surface. Some also try shining light from far side while looking directly along the sealing surface to see any light passing 'tween.

If needed, put some 200 or finer wet/dry sandpaper, WD40 or similar oil on paper and move the bowl around in a figure 8 to make it dead flat again.
 
Nortorious said:
Thank you! Yes, I fixed the needle groove and float bowl already and that stopped the gas leak. I'll be interested to see how it improves after some new gaskets. Ordering now..


The carbs are L36 932 and R36 932
Click to expand...

When you get your new gaskets make sure they do not encroach on the floats
 
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Alright just ordered Amal part 622/208 which is a gasket set for both carbs. I have a feeling they will need more love after this.

I've read Bushman's tuning secrets 100 times and I still don't quite get it. It's printed out and the official bookmark of my shop manual. I must have a carb learning disability. One day it'll click..
 
Nortorious said:
I've read Bushman's tuning secrets 100 times and I still don't quite get it.
Click to expand...

The screw plug modification makes it easier to access the pilot jets for cleaning as the jets often become blocked if fuel is left in the float bowls for any length of time.

Nortorious said:
This is intriguing.. what's a Mk2 doing on my 1973. Is this a common upgrade?
Click to expand...

Is your "1973" model's serial number earlier or later than 307311 as later would make it a Mk2?

There's really no difference in specification between between 850 Mk1 and 850 Mk2 model carbs (not to be confused with Amal Mk2 carbs) so not exactly an upgrade even if it is a Mk1.
 
L.A.B. said:
Is your "1973" model's serial number earlier or later than 307311 as later would make it a Mk2?

There's really no difference in specification between between 850 Mk1 and 850 Mk2 model carbs (not to be confused with Amal Mk2 carbs) so not exactly an upgrade even if it is a Mk1.
Click to expand...

I did some digging and the previous owner did note that he added a "New Amal Premeire 932 anodized slide, adj float"

Can't wait for my gaskets..
 
EstuaryBoy said:
TBH that's why I wouldn't go down the allen screw route for these. Only room for a small screwdriver which helps negate the possibility of over tightening :-)
IMHO...
Click to expand...
Actually the allen heads make for easy top or bowl removal while on bike, tank in place. No worry on over torque it not using the long arm or just holding it near the screw head.
 
Tornado said:
Actually the allen heads make for easy top or bowl removal while on bike, tank in place. No worry on over torque it not using the long arm or just holding it near the screw head.
Click to expand...
Having done this chore today, I will say that one of the bolts is tricky to get at with a straight screwdriver and an allen key would have made it a bit easier I imagine.

That said, I usually go for the original bits unless they are flawed.
 
Nortorious said:
Having done this chore today, I will say that one of the bolts is tricky to get at with a straight screwdriver and an allen key would have made it a bit easier I imagine.

That said, I usually go for the original bits unless they are flawed.
Click to expand...
My original screw were a bit knackered from previous owners using standard cross point/Philips drivers. To help the new cross point type screw heads from damage, be sure to use proper JIS driver bits or screw drivers. These just fit so much better.
 
Tornado said:
My original screw were a bit knackered from previous owners using standard cross point/Philips drivers. To help the new cross point type screw heads from damage, be sure to use proper JIS driver bits or screw drivers. These just fit so much better.
Click to expand...
Guilty. Fortunately I bought a 4 pack so was able to replace my roadside hack job with a new bolt driven properly.
 
Tornado said:
My original screw were a bit knackered from previous owners using standard cross point/Philips drivers. To help the new cross point type screw heads from damage, be sure to use proper JIS driver bits or screw drivers. These just fit so much better.
Click to expand...

Are the Amal carb float bowl screws JIS or Pozidriv? I can't get consensus from a search and they have markings that make me think Pozi but I'm not sure..
 

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  • My carb fell off. Oof.
    622-086-01-NORTON-BSA-TRIUMPH-ETC-GENUINE-AMAL-CONCENTRIC-CARB-SCREWS__25092.1588372782.1280....webp
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I have had float bowl screws come loose after riding hard up a mountain. Since then I drill and lock-wire the screws and the nuts, etc holding the carbs and manifolds on. I do the lock-wire procedure after everything's sorted out. Sitting by the side of the road hunting for screws in the gravel is a drag, and a bummer. At one time someone (don't remember who) sold 2BA thumb screws with locwire holes already in them. I still have 4 though I don't use them.
 
Thomasa said:
I have had float bowl screws come loose after riding hard up a mountain. Since then I drill and lock-wire the screws and the nuts, etc holding the carbs and manifolds on. I do the lock-wire procedure after everything's sorted out. Sitting by the side of the road hunting for screws in the gravel is a drag, and a bummer. At one time someone (don't remember who) sold 2BA thumb screws with locwire holes already in them. I still have 4 though I don't use them.
Click to expand...
I came across those today in my search:

"Amal float bowl screw w safety wire 376/151 622/086 576/079 Concentric monoblock"
steadfastcycles.com

Amal float bowl screw w safety wire 376/151 622/086 576/079 Concentric monoblock

Amal float bowl screw w safety wire 376/151 622/086 576/079 Concentric monoblock
steadfastcycles.com
 
Nortorious said:
Are the Amal carb float bowl screws JIS or Pozidriv? I can't get consensus from a search and they have markings that make me think Pozi but I'm not sure..
Click to expand...
I have a Vessel JIS impact screw driver set that fits the amal screw nicely.
This image is from an article ifound describing differences of philips, jis and pozi:
My carb fell off. Oof.


bike.bikegremlin.com

Phillips, JIS, and Pozidriv screwdrivers explained | BikeGremlin US

There are cross-head (Phillips) screwdrivers that don’t slip when unscrewing a tight screw. How to tell those, what are the differences? What are JIS screws?
bike.bikegremlin.com bike.bikegremlin.com
 
Tornado said:
I have a Vessel JIS impact screw driver set that fits the amal screw nicely.
This image is from an article ifound describing differences of philips, jis and pozi:
View attachment 97023

bike.bikegremlin.com

Phillips, JIS, and Pozidriv screwdrivers explained | BikeGremlin US

There are cross-head (Phillips) screwdrivers that don’t slip when unscrewing a tight screw. How to tell those, what are the differences? What are JIS screws?
bike.bikegremlin.com bike.bikegremlin.com
Click to expand...
posidrive always have the 45 degree markers on the flat face.. easiest way to spot... learnt from many years noting mixed fasteners supplied with different parts of DIY products!
 
Nortorious said:
did some digging and the previous owner did note that he added a "New Amal Premeire 932 anodized slide, adj float"
Click to expand...

Edit:
Just the slide and float (and alloy float needle?) and only one set, as those parts aren't exclusively Premier items? :confused:
If it was a L/H Premier carb then the screw I thought was the Bushman's modification should be the Premier pilot jet.

Nortorious said:
Are the Amal carb float bowl screws JIS or Pozidriv? I can't get consensus from a search and they have markings that make me think Pozi but I'm not sure..
Click to expand...

Cross head screws on British bikes are normally Pozidriv.
 
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Odd that a previous owner would go to the trouble and expense of installing Premier parts (stay-up float, Viton tipped needle, anodized slides etc.) and then not fit gaskets to the bowl(s?).
 
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