Thanks for your informative and detailed analysis, it was very helpful and greatly appreciated.

My Air mixture screws was corroded into the Zinc alloy. took 3 hours to get out each with thin oil, heat and re-cutting the screw slot - thread in the housing was completely flattened and had to be re-cut with a tab. I only had the gasket kit so had to be careful with all the parts - also 30 years ago now.. Got it driving ok.. leaked from one carburettor when on the side-stand so had to close for the fuel even for a few minutes break. It was also burning sparkplugs.. but when the spark adjuster plates was freshly adjusted, weather was cold and moist it was really driving nicely. - though a CB500T (1975) so it also had the de-acceleration diaphragms that I also had to replace as the rubber was falling apart. Before the renovation it was crazy.. fire out the exhaust, running slow and uneven until it sometime kicked in and burned allot of fuel and did not react to the throttle but just accelerated - still with fire out the exhaust.. fun bike. Ended up quite ok after some years of convincing it to behave.

Those are not phillips head screws, you can tell by the little dot. They're JIS and you'll mangle them if you keep using a phillips driver in them.

I tried myself for my K1 (before they offered this video) and ended up sending the carbs to Common-Motors and they came back fine in only a few weeks and only charged me $60 for labor for the two carbs. So now that I am having a surging problem on one carb on my K5 and have already spent hours messing around I am again going to send the carb to these experts. It costs a bit more than DIY but saves hours and they have all the parts so is a very good deal.

Very well done.. Thanks for sharing 😊

Great video which I used to successfully fix my float needle/fuel leaking problem. One thing I don't get though is how it was that whilst your discharge nozzle needed punching out, it went back in so easily. I needed to punch mine back in which made a tiny sliver of swarf. I think I'll leave it in when I rebuild the other carb.

5:14 I've been told to leave the discharge nozzle alone for the most part. On my CB750 I think they're called needle jet holders. They're usually stuck in the carb body and tapping them out can break or distort them. They don't usually need replacing. The first time I cleaned my carbs I broke a couple of those nozzles taking them out. The replacements I bought weren't the exact same size as the original parts. I try not replace any of the brass parts that are in decent shape, just clean them up and re-use them. The needle valve springs can lose their springiness over the years, so I tend to replace those. I love the 70's Honda CB's, they're really easy to learn to work on and there's lots of parts and videos (like this one) available to help you if you're a newbie like me.

Thank you for this

That “aluminum plug” at the bottom of the carb. What is it called? As I was putting my carbs back together with the Common Motor rebuild kit, I just found out that one carb that I was having some trouble with was missing that plug all along. Would this be a cause of the RPMs spiking sporadically?

great video but can you make a video more angles of setting this type of carb float height?

I have been unsuccessful finding Allen Head Screws for the Slide Cover. JIS M5 x 0.9 Honda Socket Cap Screws are unavailable on the market. M5 x 0.8 is the closet that I could find. Do you have M5 x 0.9 for sale ? Thanks, Larry

great video, I need mine rebuild, I live in California do you rebuild carbs ?

Do you not need to replace the needle jet as well? Normally they are worn oval and cause low speed/idle issues?

The jets and the tubes, will the punching them out damage them?

Should have checked the small o ring and washer inside idle mix screw. Reasons why some can't idle if left inside.

Do you guys have a video about how to remove the carburetor?

I have the same cb450k3 carb and it has no bowl overflow nozzle...I bought the gas line for it just to realize there's no nozzle, what in the world? Has mine been modified?

17:25 - What is the purpose of the top plastic top? Why not all metal? What is the engineering answer behind the design of those? Always have been curious. Nice video, btw. My overflow tube was leaking gas pretty heavy. Looked at the float and it was about half full of fuel and about as heavy as a fishing sinker! Poor ole thing was probably original in my 69 CL450. Keep up the great videos!

1973 Honda CB450......gasoline leaks out onto the floor when I set it to reserve tank....it does not leak when I have fuel set to on or off. Any suggestions for a fix?

great

I rebuilt my CB450K7 carbs and now they’re flooding out every time i open the fuel valve. Is that a float height problem?

My 500T has air by pass valve that has a diaprahm. do you have this on stock, the diaprahm?

Am confused with the float height and fuel level terms? The offical Honda workshop service book says fuel level is 20mm and set but setting the float height "H". The book goes on to say setting mark "H" is 14? So is the float height set to 14 from the top of the carb fuel bowl to give 20mm of fuel from the bottom when filled?

What if the dome is missing the plastic cap? Just epoxy it back up? Or would hot glue hold?

IV done it all perfectly like video. But if I forgot to switch off my petrol it's stlll dripping. If I leave the bike for a week. The gas goes in the engine. Messy !!!! So I have to switch off gas all the time I live the bike Is anyone know why it's still dripping

How would you go about adjusting the slide needle?

What year is this for?

What size main jet is recommended for operation at 5000-10000 ft altitude?

Don't CB450s normally run a 145 main jet?

Have you put out a tuning video?

great