Carb flanges on my 850 are leaking. I have taken them off, flattened them on an engineers plate and checked them for flat with engineers blue. Everything was perfect. Replaced onto the bike, still no luck. Checked with carb cleaner spray etc.
Sealed them with Blue Hylomar, then Welseal, then locktite silicon sealant. And on all three occasions they failed, instantly.
Each time the faces were checked and new O rings were fitted. There are no problems with slides jamming and all nuts were lightly tightened up, not mullered!
Next, I may try a gasket to help seal them. Anyone had this trouble before. And if so, what seal did they use?
Surely if the carb flanges…
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After months of faffing with…
After months of faffing with the old carbs I found the manifold to head was leaking, but only by the time I had bought new premiers. Also the Allen bolts were bottoming out in the thread. These are an unbelievable pain in the backside to get started and do up anyway which had put me off investigating earlier. I used a diamond hone, for chisels, on the faces and shortened the bolts both easy jobs. This also led me to wondering if previous honing had led to the bolts becoming the wrong length?? I had found out there is no sealant here so bought new heat insulators which are shiny to match the honed faces. Finally, I get to enjoy the shiny new premiers!
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Surely if the carb flanges are dead flat but it still leaks, then it must be the thing it is bolted to not being flat.
I would ease the studs out of the manifolds, check for flatness and any raised portion around the stud area, countersink slightly if required.
All being flat, you should only need the insulator and O ring with maybe a slight smear of wellseal to be sure.