Topic: Kehein roundtop carb slides!? How do I get these tiny screws out!!!

[Xkylescorex]

So I spent all day today rebuilding a set of kehein roundtop carbs. I believe these were on a 76  Anyway when I get to the main needle part of the rebuild I ended up stripping every screw. I actually didn't even try on the last carb. I ended up taking some super fine sandpaper and cleaning up the main needle but seriously, I cleaned them, soaked them in PB blaster and then hit it with a torch and I felt like I almost melted the slide. Doesn't look like anyone makes replacement parts. What should I do now?

In other news. I looked at my post history and my last post was when I bought this bike in 2016. I've been rolling it from storage to storage for almost 10 years loll. It still doesn't run. But I'm getting closer!

[Xkylescorex]

After 9 hours of straight carb scrubbing. I got them on and of course all the floats  overflow. I gotta reset all the floats. At least it sputters a little. Doesn't really run. Next step is check points I guess.

[CycleRanger]

Do you have set of JIS screwdrivers? If not you should get a set.
They make a huge difference, especially for the smaller screws.
These bikes use JIS screws, they look like Phillips but they're not.

[scottly]

all the floats  overflow. I gotta reset all the floats. At least it sputters a little. Doesn't really run. Next step is check points I guess.

Fix the overflowing floats before moving on to the ignition.

[newday777]

After 9 hours of straight carb scrubbing. I got them on and of course all the floats  overflow. I gotta reset all the floats. At least it sputters a little. Doesn't really run. Next step is check points I guess.

1st off, welcome aboard the forum seeing you haven't been yet.
2nd. JIS screwdrivers are a necessity for working on these carbs (and the rest of the bike) to get the screws off and save the screws as they grab the screw head far better without damaging the head. (Vessel makes a great set)
3rd. How exactly are you cleaning the carbs? Spray cleaner?

Are you putting 76 carbs on your K2?(you haven't given the full story, a lot of details missing)
Did you buy carb kits from 4into1.com like you bought the starter switch from?
Why the torch on the needle?

https://www.vesseltools.com/handtools/screwdrivers/megadora/9802sc-detail

BTW the original carbs came with Keihin brass which is manufactured far better than any aftermarket carb kits can give, you will have so many problems trying to use the brass from aftermarket kits

[newday777]

And if you bought points and condensers from 4into1.com, don't waste your time using them. The condensers fail almost immediately and the points are not acceptable either. Pure Chinese junk.
If you clean the original points up with a good, flexible points file they usually work. If you have to replace the points and condensers get them from Honda directly, get the whole points plate assembly (it's cheaper than buying the individual points and condensers separately).

https://www.southsoundhonda.com/--xpartsstream#/Honda_Powersports/CB750K2A_MOTORCYCLE%2c_JPN%2c_VIN%23_CB750-2000001/POINTS_%2b_SPARK_ADVANCER/78d6b920-62a4-40b9-b85b-e5ab2abab37c/431f2f9e-a95d-45b4-846f-990537e73c6a/y

[newday777]

How did the inside of the carbs look before you started cleaning them?
Pictures?

[Xkylescorex]

Thanks guys. I don't have a set of JIS screwdrivers but I guess I'm going to get a set asap. Rebuild kit looked cheap. I think I gotcit from 4into1 years ago. I didn't even remember having it. I actually have 2 projects, a 76 and a 72. I've been working on the 76 off and on since 2016 (moved and didn't have a garage, finally got a workspace)

The carbs were the worst I've ever seen, there was so much dirt and sludge in the bowls I had to start sandblasting the float bowls

I started the 76 carb rebuild first and finished it. To try and test them .I slapped em on the 72 as it would run on starter fluid kinda.I think once I fix the float bowls and check the points and plugs I can get her to run.
My goal is start a long haul restore of the 82 and maybe chop the 76 or turn it into a cafe. I also have a 73 cb360 scrambler. My add keeps me running in circles with all these projects

[newday777]

OK.
How did you clean your carbs specifically?

[newday777]

Do you have Hondaman's book on restoration of the 750?
He has a good cleaning explanation of the carbs and internal ports and cleaning the original brass.

http://forums.sohc4.net/index.php/topic,65293.0.html

[Xkylescorex]

Oh sorry.
I pulled them apart one by one. Used b12 chemtool and just scrubbed the crap out of them I replaced ai watched ll the jets and needles in the kit. I noticed in my rebuild kit the jet for what I think you hook up a vacuum meter to sync the carbs had a small hole in it. The jet on my carbs was a plug with no hole so I just reused those. Other than the slide with the tiny screws everything else was uneventful. I found a great YouTube channel called " Hack a day" and dude did a great walk through. I do have a Clymer manual but not the hondaman manual.

[Xkylescorex]

Here is a picture of my 1976 that the carbs came from. I got this at an estate sale as well. Looks like it has some aftermarket hotrod stuff on it but had stock airbox. My friend is all about the wheels for some reason. I've been rolling this one around for 6 years lol

[CycleRanger]

You can download PDF's of the Honda shop manual and parts lists from here:
https://www.honda4fun.com/materiale/documentazione-tecnica

They are much better than the Clymer manual. 

[Xkylescorex]

Carbs off the 72 are in better shape than the 76 carbs and are mikunis. Here's a pic. The 76 carbs I rebuilt literally looked like there was a teaspoon of sludge / mud in the bowls. Everything was wrecked. Also attached pics of my cb360. I'm fighting with getting vm34 mikunis jetted right and a Evo sportster I'm turning into a o0s street fighter. Evryone hates it.

[Xkylescorex]

Thanks cycleranger! I have a big zip of hundreds of manuals from back in the chopper underground days. I need to find it and see if the hondaman manual is there. The Hacka day guy says that's the best one to have.

[MauiK3]

+1 Hondaman's manual
Must have

[newday777]

Thanks cycleranger! I have a big zip of hundreds of manuals from back in the chopper underground days. I need to find it and see if the hondaman manual is there. The Hacka day guy says that's the best one to have.

Hondaman's book is different(is not downloadable)from the Honda Service Manual that you can downvideos.
Hondaman is a long time member here and still posts regularly.
Hackaweek had a good series of YouTube vids.

[newday777]

Here is a picture of my 1976 that the carbs came from. I got this at an estate sale as well. Looks like it has some aftermarket hotrod stuff on it but had stock airbox. My friend is all about the wheels for some reason. I've been rolling this one around for 6 years lol

Those wheels are Lester wheels. They were a common accessory wheel back in the 70s.
7 spoke, 2 ribs to the spoke as you have. You can run them tubeless if the beads are good.

[Stev-o]

Carbs off the 72 are in better shape than the 76 carbs and are mikunis. Here's a pic.

Those do not look like Mikunis. Wrong pic?

[newday777]

Carbs off the 72 are in better shape than the 76 carbs and are mikunis. Here's a pic.

Those do not look like Mikunis. Wrong pic?

Read the rest of that post. I thought the same until I read the rest of it

[seanbarney41]

Those little screws in the slides can be massively problematic.  You may need ...
1.long, thin shanked screwdriver that fits the JIS screws as perfectly as possible
2.  Penetrating oil and heat...note that the hole the screws thread into can be seen and accessed at the other side, I.e. holes go all the way through
3.  A small drop from a 2x4 with a hole drilled through for the needle will allow you to get very aggressive with the slide without damaging it.

[scottly]

Is it absolutely necessary to remove those screws? 

[newday777]

He was doing it to put the 4into1 needles in.

[Don R]

 If no one has said it yet don't use the 4-1 brass. The stock brass when properly cleaned is always better. If you have 4-1 brass and stock needles don't expect it to run right.

[seanbarney41]

Is it absolutely necessary to remove those screws? 

It is, if you need to change the clip position or need to be sure that the clip position has not been incorrectly installed.