CB450 Carb rebuild help

[Doc.]

Hey guys,

I'm about to tackle my carb rebuild part of the project, and honestly I have no clue what I need to be doing to "clean" them up. I've read that boiling them in pure lemon juice helps, but is that for getting all the gunk and stuff out of the passages? Also, should I pull everything off of the carb (butterflies, etc.) before the boil, or leave them in there? Is there a how to for a complete clean and rebuild of the carbs?

Thanks.

 

[lingo]

don't pull the butterflies. When I did mine I pulled the the top cap and slide out. then pulled the the bowl, float, jets and idle screw. Then I boiled the carbs. all of the brass pieces where soaking in carb cleaner while the bodies were boiling and I cleaned the the other pieces with degreaser and a stiff brush. after the carb bodies dried, I soda blasted then and reassembled.

 

[Doc.]

Thanks lingo. I actually cleaned one, and pulled everything apart, but did boil all the parts but the jets, the air/fuel mix screw, and the cap and piston slide.

I do have alot of corrosion in the slide and the cap, any tips on how I should clean them?

 

[lingo]

honestly, I would try to replace them. And do it in matched pairs (slide and cap pairs). The machine tolerances in those things is extremely tight and you want them to move freely. vacuum has to be able to pull that aluminum slide up into the cap.

 

[Doc.]

Can they still be purchased through Honda?

 

[Doc.]

Welp, Honda has discontinued the vacuum piston set. I couldn't find them online either. Looks like I'm going to have to figure out a way to clean them. The piston still creates vacuum pressure pretty well. I just need to clean the inside walls of the cap so they ride smoother. Any tips? I was thinking just a light sandpaper.

I'm also toying with the idea of getting some Mikuni VM30s. You can get them from amazon for $78 a piece. Do you have to buy the intake boot as well, or do they bolt up to the factory 450s?

 

[Doc.]

Here's a pic for reference. I think only one of them is this bad.

 

[crazypj]

Use a brass wire brush to get corrosion off then some 600 grit with WD 40 to polish periphery of piston and inside vacuum chamber.
They will work

 

[Doc.]

The actual piston and chamber is really clean, it's just the outsides of the cover and stuff. Should I use any chemicals with the brush? What about using the sand paper on the surface where the corrosion is?

 

[crazypj]

Chamber doesn't look too clean to me?
It needs to be smooth and polished inside the 'cup' part
The center is more of a guide tube.
Piston should drop slowly if you fit it into vacuum chamber without damper spring, 90%+ of air should come through the lift holes and not around piston

 

[Doc.]

It's just the lighting I think. I'll take better pics in the daylight. It still holds suction pretty well and the air comes out of those little holes when the piston is pressed in.

 

[lingo]

PJ, just a side note. the cb450 carbs don't take a damper spring. I don't want Doc looking for them because he won't have them

 

[crazypj]

I haven't worked on them for such a long time I had forgotten they use just the slide/piston weight : .
Thanks for reminding me ;D

 

[lingo]

No sweat, You are much better with carbs than I am. From what I have seen the 450 carbs are quite different than any of the others that Honda used. Kind of like the rest of the engine.