Topic: CB750K4 Carbs Cleaning

[myhondas]

So like I stated in another thread, My bike was in storage for 22 months, and needless to say, it was a mess when I pulled it out. I have cleaned out the tank and have that back in shape, but my problem now is the carbs. Slides were frozen and bowls were full of crap. I have gotten the slides working again and now need to get the bowls, jets, and orifices clean.  I know, I know....I should not have left anything in them...but I wasn't planning on letting it sit for that period of time (Covid 19 was the cause). Looking for suggestions on what will be the fastest and best method of getting these back into clean working order. I need to be able to ride this by Sept 18.

[markreimer]

That’s not really that bad. I’ve had carbs way worse. It’s a one or two day job at most.

I’d start by removing all the brass bits. All the keys, needle jet/jet needle, mixture screws etc. leave those to soak in Berrymans or some equivalent carb cleaner for a few hours.

For the carb bodies, I leave them in an ultrasonic cleaner for an hour, using Power Kleen or whatever strong cleaner of choice. Once finished I blast all the passages with carb cleaner and compressed air.

That’s usually all it takes. Reassemble, lightly lube the slides and linkage, slap em back on


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[pjlogue]

Be sure to keep the fuel float needles with their respective seats.  I.E. don't mix parts between carbs.  A really good investment is getting a cheap ultrasonic cleaner.  Short of that, I would run some carb cleaner through the slow and primary jets, through the internal passages (with idle air needles removed) and use the carb cleaner on the bowls and bodies.  They are in good shape already from the pics.

They should clean up well.

-P.

[markreimer]

Ah yes, knew I forgot something - I'l second Pjilogue's note about keeping the float needles matched. Been there...

[HondaMan]

Those aren't bad! If you can go to NAPA Auto Parts and get their 1-gallon can of carb cleaning solvent (with the little basket in it) you'll be able to do all 4 over a weekend. The bodies, bowls, jets and needles can all fit into the basket, let them soak at least 4 hours and then spray them clean with some Brake Cleaner spray (wear gloves...) for the fastest fix-up. I do a more complete job then that when I clean someone's set for them, but those are the 2 main solvents I use (plus lacquer thinner) to loosen the crud.

[ekpent]

 As mentioned those look good compared to some I have done. Agree with Hondaman and by some Gunk or other brand carb dunk that used to be in gallon cans but like ice cream has been reduced in size for the same price    If you want to do it right you will need to separate the carb bodies off from the rack and get the slides and needle out and each body can fit in the can.. Replace the o-rings (2x8mm I think) on the 2 fuel tees while its apart and might as well replace the 4 orings for the drain screw also. Think I use 3/32 but would need to double check. When I use the gunk brand I rinse in clean water and blow out everything with compressed air.
   The good thing are these roundtop carbs are the easiest around to do.   Don't forget to take out the air screw and the little springs also first and they are set at a one turn out baseline.

[Mark K]

While I haven't tackled the disassembly and cleaning of my carbs ('73K3), I've been searching for the best method to do it. Came across this video last evening. The guy demonstrates soda blasting versus the berrymans Chem dip, as well as using an ultrasonic cleaner. Video is about 17 minutes long.

Might be of help?

[HondaMan]

While I haven't tackled the disassembly and cleaning of my carbs ('73K3), I've been searching for the best method to do it. Came across this video last evening. The guy demonstrates soda blasting versus the berrymans Chem dip, as well as using an ultrasonic cleaner. Video is about 17 minutes long.

Might be of help?

It took me a week, every evening, to clean out the soda from the tiny passages in a set of carbs someone did with this method. If you do it, tape off the main passage thru the carbs (or put a small rubber ball in each end) because the soda should NOT be allowed to blast into the tiny passages!

[Mark K]

Hondaman, was it wet or dry soda? I'm only asking, as the guy in the video said that you do not want to use dry soda. And if you use wet soda, you have to rinse/soak in water to make sure all soda is removed.

As I don't have any way to blast with ANY type of media without a large amount of cash layout for a blasting cabinet and all the required accoutrement, I'm left with using Berrymans.

[markreimer]

How would you blast wet soda? It turns to sludge and then dissolves?


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[Mark K]

I don't know 🤷🏼‍♂️, just relating what I thought I saw in the video. Maybe I didn't understand it correctly.

[markreimer]

I don't know , just relating what I thought I saw in the video. Maybe I didn't understand it correctly.

Just looked it up. It’s a supersaturated solution of soda in water. That’s pretty cool actually!


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[newday777]

I don't know , just relating what I thought I saw in the video. Maybe I didn't understand it correctly.

Just looked it up. It’s a supersaturated solution of soda in water. That’s pretty cool actually!


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Known as Vapor Blasting

[markreimer]

I don't know , just relating what I thought I saw in the video. Maybe I didn't understand it correctly.

Just looked it up. It’s a supersaturated solution of soda in water. That’s pretty cool actually!


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Known as Vapor Blasting

I always assumed vapor blasting was glass beads in water. Learned something new today


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[Kevnz]

My 500 carbs were totally seized, slides gummed up. Tried liberal amounts of CRC, no dice, but acetone cleared the varnish off completely in seconds. Ditto the crap in the float chambers.