Can’t find a visible air leak!
Discussion
Also a possibility that the float chambers are simply full of crap, and its being jogged into the jets when you go over bumps, partially blocking them.
So when you take the tops off to set the float heights, clean out the float chambers and take the jets out to give them a good blow through with a high-pressure air line, while you're at it.
So when you take the tops off to set the float heights, clean out the float chambers and take the jets out to give them a good blow through with a high-pressure air line, while you're at it.
I have the book, its not bad, my carbs are actually Dellorto DHLA 40's, but very similar to the Weber 40's/45's.
Never actually checked the float level, but found it fairly painless to change the seals (bowl seal and accelerator diaphragm mainly) and wash out the bowls. It was all actually quite clean but I had read horror stories and accelerator diaphragms failing and throwing petrol into engine bay.
The other thing to look might be the gaskets between the inlet manifold and carb, and the isolating washers under the stud nuts, which will be some sort of thick rubber affair such as misab gaskets. These in effect stop vibrations coming from the engine into the carb. If its only effects you after a bump it might not be that, but they go hard over time and a lot of people over tighten them and loose all the isolation. If you having the carbs off anyway I would likely replace them unless you know they are fairly new and in good condition.
Daniel
Never actually checked the float level, but found it fairly painless to change the seals (bowl seal and accelerator diaphragm mainly) and wash out the bowls. It was all actually quite clean but I had read horror stories and accelerator diaphragms failing and throwing petrol into engine bay.
The other thing to look might be the gaskets between the inlet manifold and carb, and the isolating washers under the stud nuts, which will be some sort of thick rubber affair such as misab gaskets. These in effect stop vibrations coming from the engine into the carb. If its only effects you after a bump it might not be that, but they go hard over time and a lot of people over tighten them and loose all the isolation. If you having the carbs off anyway I would likely replace them unless you know they are fairly new and in good condition.
Daniel
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