Fixing Leaky Carbs | Honda CB750 Carburettor Repair | Motorcycle Project | Part 12

Fixing Leaky Carbs | Honda CB750 Carburettor Repair | Motorcycle Project | Part 12

In this bitsa CB750 Restoration episode, I finally fix the leaking float bowls of my Honda CB750 K series project bike. Fixing the leaky carbs turned out to be more of a mission than I’d originally anticipated, but I think they’re now successfully repaired.

Here's what I used in this video:
Blow torch: https://ebay.us/Wstfop
Soldering Flux: https://ebay.us/QdHNtI
Fire extinguisher: https://ebay.us/Mks7nC
JIS Screwdrivers: http://ebay.us/R2brPs
Auxiliary fuel tank: https://ebay.us/otHb8C
Brake and Clutch Cleaner: https://ebay.us/ibW7Zu

After becoming very quick at removing and replacing the carbs, and setting the float levels I came to the realisation that it wasn’t the fuel valves causing the leak. I suspected either the drain plugs or the brass tubes used for the breather/vent pipe.

I took off the offending float bowls and the pipes didn’t look too clever. There weren't any obvious splits or holes, but they did have a lot of pitting and black marks that could have been hiding anything. I filled the float bowls with fuel to see if they leaked, and they did straight away.

I part emptied the float bowls so that only the drain plugs were covered by fuel, to check that it wasn’t them. It wasn’t!

Researching leaking breather/vent tubes it seemed the 3 options are, new float bowls, solder the splits, or remove the tubes and put in new. There aren’t any new ones that I could find, and second-hand ones might also have problems.

So I decided to try the solder route first. I have a little experience of putting water pipes together, but I expected trying to fix invisible holes in a tight space might be beyond me! :)

I had read that you needed to get the tube as clean as possible, then use flux to get the solder to run into the splits or holes. As I couldn’t see the splits or holes I tried to cover as much of the surface as I could with solder.

After my first attempt, one of the bowls still leaked. I realised that I had concentrated on the bottom end of the tube and that the issue might have been at the top of it. So I had another go.

Although my soldering wasn’t pretty, in fact it was horrible and lumpy, it did the job so I was quite pleased. I tidied it up with some abrasive paper so it didn’t look too bad.

This seems to be a fairly common problem, so I am pleased that I now have a technique in my armoury for when I come across it again.

For more helpful how-to guides and restoration project logs, visit our blog: https://www.spannerrash.com/

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Видео Fixing Leaky Carbs | Honda CB750 Carburettor Repair | Motorcycle Project | Part 12 канала SPANNER RASH