1966 Atlas: Amal 689 Monoblock right side leaks fuel from float chamber cover

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pierodn

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Hi All.
I need your suggestions.
My 1966 Atlas right side Amal 689 Monoblock leaks a lot of fuel from the float chamber cover.
The gasket is new and the float and the viton too.
The three screws of the float chamber cover are well thighten.
Note that now is the first time that the carbs are received fuel after overhaul.
The left 389 doesnt leak.
Thank you.
Piero
 
Last edited:
Float chamber/carb body is warped, cover is warped, or both. You can try using a different cover, lapping the surfaces for a better fit, or maybe a thicker gasket.
 
Yes, if the gap isn’t too large. I’ve used a type of sealant specifically for gas on the gasket that goes in the monobloc for the jet block.
 
Hi All.
solved the fuel leak with two gaskets!.
But now i have another problem.
When i tight the main jet holders the throttle slides stuck that is they are no longer very free.
What i must check now?.
Thank you.
Piero
 
That's a puzzler. Are you tightening the jet holders while the carbs are on the bike? Maybe you are torquing the jet holder so much that you are twisting the carb bodies and distorting them?
 
Try loosening the jet hold until it no longer binds. Maybe it is too tight? With good fiber washers it doesn’t take a lot to tighten everything and I find after a couple heat cycle and gas exposure things seal better.

Do you have the set screw in the carb body located correctly against the jet block?
 
Hi, on my atlas, the sealing surface of the float chamber cover was no longer flat and I did it as shown in the movie. worked. - Best Jörg/Germany.
 

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