Amal de-warping jig

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acadian

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Found this tool posted on the BB forum while searching for info on my A65, I believe the bike has the original carbs (no drain plug in the float bowl), and they are in OK shape aside from the stuck slides, so I fabbed this up and it does the trick. I warmed the carb bodies up a bit, and used some shims under the stud flanges... cranked it down and voila! No more sticking slide

Amal de-warping jig
Amal de-warping jig
 
Flattening the flanges keeps the slides from sticking? I'm dense.
 
Yes, but the bore must also be re-aligned to the flanges, that's what the tool acomplishes

http://www.britbike.com/forums/ubbt...oncentrics-is-there-really-no-cure#Post664246

Just lightly warmed with a heat gun

Hi acadian ( from another Nova Scotia acadian)
Good show ...what's old is new again...lol
You might see this warpage more on BSA's?
Folks that use the thick crappy paper/cardboard gaskets right on the carbs are notorious for warping them. This is big NO NO for me. I refuse to use ANY gasket on oringed carbs on nortons. However mid 50's and older carbs were flat faced/ no o-ring.
I have a drawing in my carb files of this almost exact same thing. Having mostly Nortons, I did not have as big a need. Never finished making one.
Sold all my A65's decades ago...
Now only A-10 (3)
I had been able to tweek mine a bit with big channel locks around the top of the slide bore to stop the sticking. However I no longer would flatten by sanding the flange. As we know it does not really fix the problem.
 
Hi acadian ( from another Nova Scotia acadian)
Good show ...what's old is new again...lol
You might see this warpage more on BSA's?
Folks that use the thick crappy paper/cardboard gaskets right on the carbs are notorious for warping them. This is big NO NO for me. I refuse to use ANY gasket on oringed carbs on nortons. However mid 50's and older carbs were flat faced/ no o-ring.
I have a drawing in my carb files of this almost exact same thing. Having mostly Nortons, I did not have as big a need. Never finished making one.
Sold all my A65's decades ago...
Now only A-10 (3)
I had been able to tweek mine a bit with big channel locks around the top of the slide bore to stop the sticking. However I no longer would flatten by sanding the flange. As we know it does not really fix the problem.

Hi Dave, you're of course correct, more likely to show up on Triumphs and BSAs, the excerpt posted by Healy notes that its' less likely a problem on nortons whose carbs bolt directly to the manifold. Sure enough, both my Triumph and A65 have the tufnol spacers between the carb and manifolds (even described as such in the manual).

Amal de-warping jig


This was more of a social distancing/time-wasting project than anything else, as I'll most likely replace the A65 carbs with premieres and keep the originals on my wall... ;)
 
The pix shows kinda what I expected. Gasket at the head and insulator next to the carb. JH and I talked a little about this thick paper/cardboard at the carb. He knows the hard G-10 style insulator was superior but that tri/BSA guys were to cheap to buy the good ones and settled for the fiber ones and later paid the price with bent flanges.
This same pix on nortons up to around 1960+/- has the insulators at the head.
 
This de warping seems to only address flange and bore distortion, not wear between bore and throttle slide. The resleeving route should still be a good alternative as it addresses both wear and warpage (at least in the bore).
 
On the other hand, I like the red phenolic heat insulating spacers.

A cooler carb seems a good idea
I had a slide jam in fully open position after a fuel stop. Had not started engine yet, just gave throttle grip a quick turn and it did not return to closed. Found the single amal carb body on the bike atthe time too hot to touch. It had soaked up the engine heat in the few minutes it took to fuel up. This distorted the carb enough to jam the slide. Maybe the two into one manifold helped transfer heat compared to two singles due to surface area differences. Once it had cooled enough to be touchable again, throttle closed normally.
Now I run the thicker type of insulators (there are two thicknesses available) and im on dual carbs with standard two single manifolds.
 
And, cooler charge air and cooler fuel in bowl are nothing but good when the engine is at standard operating temperature
 
This de warping seems to only address flange and bore distortion, not wear between bore and throttle slide. The resleeving route should still be a good alternative as it addresses both wear and warpage (at least in the bore).

Re-sleeving may still be necessary, true, but based on the information I found the sleeving/boring process is only undertaken after the warpage has been eliminated
 
Found this tool posted on the BB forum while searching for info on my A65, I believe the bike has the original carbs (no drain plug in the float bowl), and they are in OK shape aside from the stuck slides, so I fabbed this up and it does the trick. I warmed the carb bodies up a bit, and used some shims under the stud flanges... cranked it down and voila! No more sticking slide

View attachment 15069 View attachment 15070
What diameter do you recommend for the tool, My 928 is 35 milimeters roughly. Has anyone got the diameter of a new slide?
 
I learned about sticking slides the hard way! Caused me to miss my first dirt track race, and never ended up on a dirt track with a race bike. Must mean I would have been killed, or worse...
 
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