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Discussion Starter · #1 ·
Hi Folks,
I have finally taken the carbs off the 1981 CM 400 A and broke them down, Cleaned them in ultrasonic with 50/50 hotwater and Krud Kutter. Worked great.

Before:
Antique Metal Carburetor

After Ultrasonic Cleaning:
Auto part Engine Carburetor

I have a couple of questions:

1.) I didn't notice what jet went were. Do'h.. So how do I know what the large jet vs the small jet and where which one goes where.
2.) I didn't notice white spacers with o-ring cant figure out where they go now. I had taken pics of the whole carb but not during disassembly and had to do a few errands then brain cramp..

Any help would be great.
Bill
 

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Discussion Starter · #3 ·
Thanks for the article it's exactly what I needed.

The white spacer is in this pic right at the top of his knuckle/
Hand Metal
 

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Thats the needle stop you put it on after installing the needles. There should be two new ones in the carb repair kit. Im rebuilding the carbs on my CB 400A. I used the NAPA carb cleaner on the body and CLR on the brass bits.It also did a great job.


Bill H
 

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Suggestion. If its been awhile since those carbs have been down take a good look at your air cutoff valves.They dont cost that much and nows the time to change them out. You could save yourself a lot of problems in the long run . When they fail they cause a vacuum leak inside the carb .

Just a thought.

Bill H
 

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Discussion Starter · #6 ·
Hi Bill H. I lucked out, I bought a 1980 cb 750 k and the previous owner gave me 4 set of carbs and 8 sets for carb rebuild kits. The air cutoff valves are identical to my CM 400a used them. Sweet.

One more thing where do these two small o-rings go? See picture with the o-rings in the red circle.

Auto part
 

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Those look like the air cut valve cover O-rings to seal the cover to the body. Other location for small O-rings is the mixture screws.
 

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Discussion Starter · #8 ·
Carbs cleaned and back togther

Finished up assembly of the carbs. Installing new carb boots and carbs this week then doing the tires.. thanks for all your help.
 
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