Honda Keihin Carburetor Adjustment

[Michael Gray]

First, thank you Erick The Car Guy for your basic carburetor rebuild and adjustment videos!

That said, I have an 80 Honda Civic with a Keihin 3bbl carburetor. I’ve rebuilt it a couple of times, but I’ve never been able to adjust it myself. My shop manual wants tools I don’t have, and can’t find. I’ve looked all over the internet for info on these things with no luck. Even folks on the old Honda forums don’t seem to know how to tune these things.

If anyone can share with me a video or website, or book – anything – I’d sure appreciate it. Thanks! 🙂

Topic

[college man]

see if this helps you.

http://www.keihincarbs.com/tips/gate.html

http://www.keihincarbs.com/home.html#

[Michael Gray]

Thanks for the links!

The video by Honda Roots is good, but its part 1, and the fellow never got around to making more. He later posted a video on how to replace your Keihin with a Webber. So I don’t think he’ll be making any more Keihin vids. 🙁

I have managed to find a few videos and websites explaining how to adjust other brands of carburetors. They all seem to have about the same technique, so I think I may be able to do the same on mine. In my experience, the Keihin is very reliable as long as you make sure its getting clean fuel. So its worth learning how to fix it up and keep it working. If things work out, I may make my own video to share. Since there seems to be a distinct lack of info on these carbs out there.

I have a re-manufactured carb on my car now, so I’m working on the original without any pressure to get it done quickly. Here’s a few pics I’ve taken so far:
I found the primary mixture screw on the throttle body.

Here’s the aux. mixture screw on the main body.

Here’s the original reason for needing a replacement carburetor. I broke the float pin holder last time I tried to rebuild it.

A reference pic for where jets and things go.

Here’s a part I can’t find on any diagrams. Some kind of vacuum controlled check valve under one of the float bowls. Seems to work ok though. Anyone know what it is?

Here it is all apart and ready to be cleaned up and repaired. I separated out all the parts into bags so it will be easier to tell later which parts go where.

[Michael Gray]

I’ve read that the valve on the bottom of my carb is called a power valve. It has something to do with sending fuel to the rest of the carburetor, and is almost always in the open position. As far as I can tell, mine seems to work ok.

The three big parts of the carb got their initial cleaning.

I use a very hot solution of water and Pine-Sol. It makes a good de-greaser that is safe for metals like aluminum and brass. It also won’t melt plastic parts, but I’d still keep rubber bits like o-rings and diaphragms out of it.
Its also not near as noxious or toxic as regular de-greasers either. I hadn’t expected to get this much gunk off the carb. When I was done, the water was black, and the bottom of the pot was covered in sludge.

A lot of my screws are getting worn. Some are bent, and they’re all Phillips (or the Japanese equivalent), and the heads are getting rounded off. I’ve decided to replace them with new Allen/hex key screws.

They all fit except for the four bracket screws. They need to be shortened just a little.

[college man]

Organization you gotta love it. Keep us posted on your progress. 🙂

[Michael Gray]

Well, since my new floats came with pins, I no longer need the three feet of metal rod I bought to make new ones.
Too bad. The diameter is perfect.

I’ve finally cleaned up all the small parts that came off the body. Found a couple than deeded replacing. I’ve got some brass tube on order that should be the right diameter to make new alignment pins for assembling the top back on the main body. For now though, gotta show off my clean parts a little:

[college man]

Looks nice. 🙂 All you used was pine sol?

[Michael Gray]

Pine Sol, water, heat, and time. Some of the more stubborn parts had to “cook” for an hour or more to loosen up the crud.
I used one pot full for the body parts, and a fresh solution for the peripherals. The most effective cleaning tools I found were an old tooth brush, and a little “pipe cleaner” bottle brush. The rubber and plastic parts can also be cleaned up with the solution, but I didn’t let them soak. Just a quick dip and some brushing.
I still plan to use a carb cleaner spray can, and compressed air, to make sure all the channels are clear.

I’ve had pretty good results with this method in the past. I mostly do small engine stuff. Like 50cc moped engines. Sometimes I’ll have to go back with a stronger chemical, but by then, most of the grease and grime is gone, and I’m only working with a few problem spots.

Now that the linkage is all clean, I wonder, what is the best lubrication for it.?

[college man]

[quote=”rebelrider.mike” post=152804]Pine Sol, water, heat, and time. Some of the more stubborn parts had to “cook” for an hour or more to loosen up the crud.
I used one pot full for the body parts, and a fresh solution for the peripherals. The most effective cleaning tools I found were an old tooth brush, and a little “pipe cleaner” bottle brush. The rubber and plastic parts can also be cleaned up with the solution, but I didn’t let them soak. Just a quick dip and some brushing.
I still plan to use a carb cleaner spray can, and compressed air, to make sure all the channels are clear.

I’ve had pretty good results with this method in the past. I mostly do small engine stuff. Like 50cc moped engines. Sometimes I’ll have to go back with a stronger chemical, but by then, most of the grease and grime is gone, and I’m only working with a few problem spots.

Now that the linkage is all clean, I wonder, what is the best lubrication for it.?[/quote]

I would not use any lubricant. It should be fine dry.

[Michael Gray]

I made a replacement for the alignment pin that was missing. Found a tube with the proper outer diameter, and did some reaming, cutting, and filing. Its a bit shorter that the original, but it will do the job.

I’ve been looking for a good product for reattaching the bit that broke off the float pin arm. I tried Seal-All, as its gas resistant, but after a couple tries, its just too rubbery, and lets go too easily. Right now I’m trying a gas resistant epoxy. Its hardened up nice in the last couple hours. Tomorrow I’ll see how it actually stands up to gasoline. I hope it works.

[Michael Gray]

Well, I’m no Eric, but here’s a video of the carb being assembled:

[Michael Gray]

Here’s a video of a similar carb being removed from an 81 Civic Wagon:

Here’s the 81 next to the 80:

[Andrew Button]

Jb weld dissolves in Gas. What you want to use is Marine Tex. I had a similar problem and consulted a famous carb Guru on this. Marine Tex is made to patch plastic gas tanks in boats, therefor gasoline proof. Jb Weld is not.

[Michael Gray]

Thanks andrewbutton442,
I didn’t use JB weld. I have also heard that it will dissolve in gas over time. I used a gasoline resistant epoxy made by Permatex for bonding metals.
It will be interesting to see how it holds up.

[Michael Gray]

Here is an 81 Keihin disassembly part 1:

[Michael Gray]

Part 2:

[Author]

Replies