Carburetor cleaning

[asmith411]

I am thinking of taking apart my VHB 26B D Dellorto carburetor for cleaning. It has 30 year old stale gas in it. The choke and accelerator cables are still attached. I've loosened the top where they enter but there is resistance, so I did not force either cable.
Is there a specific procedure for dismantling the carburetor? I'm assuming there is a way to release the choke and accelerator cables. Is there any other surprises when taking it apart that I should be aware of? Your help is appreciated.

Art

[tobydmv]

I am thinking of taking apart my VHB 26B D Dellorto carburetor for cleaning. It has 30 year old stale gas in it. The choke and accelerator cables are still attached. I've loosened the top where they enter but there is resistance, so I did not force either cable.
Is there a specific procedure for dismantling the carburetor? I'm assuming there is a way to release the choke and accelerator cables. Is there any other surprises when taking it apart that I should be aware of? Your help is appreciated.

Art

Yes the cables have balls or knarps in the end that slip into a relief in the slide. They wont come out unless you remove the slide itself. Are you loosening the cable adjuster? That will tighten the tension on the cable. You want to remove the top cap of the carb by removing the 2 retaining screws. Then the slide should come out with the cables. If the bore is stuck then we have a lot of typing to do.

[asmith411]

Does anyone have anything to add regarding carb dis-assembly? Any issues with the float and valve adjustments, etc..

Thanks,
Art

[double diamond]

Art,
The slides in VHB carbs are not a tight fit. If you have tried blowing out with compressed air and dousing with WD40 to no avail, I suspect the needle may be stuck in the needle jet from corrosion or varnish. Your attempts to remove the throttle cable are being frustrated by the throttle return spring preventing the cable from sliding into position such that you can remove it. See attached pic of a VHB 30, assuming it’s similar. All VHB’s I’ve seen had an enrichening circuit on the side of the carb body, rather than a choke in the venture as you seem to indicate with your VHB26 BD (details of which I’m not familiar with). If you can lift the spring off the slide and push down on the throttle cable to lift it out of the hole the cable end is retained in, you might get the throttle cable out. Then you can remove the cap. Try to remove the clip that retains the needle. You don’t have to remove the clip from the slide which might not be possible with the slide still in the carb body. Just push the clip out far enough that it disengages the grooves in the needle. You might then be able to remove the slide. Matt

[asmith411]

I was able to remove the throttle cable at the carburetor. I had to disassemble the cable at the handle to get enough play. I removed the 2 needle valves and cleaned them.

The slide is definitely stuck. I will try to slide the retainer away from the pin to release the slide. Should I try to remove the carb base to see how much gunk is in the bowl or will the removal of the slide plate expose the bowl and float. There was still some rancid gas in the carburetor.

Thanks,
Art

[double diamond]

Art,
If your carb was left for 30 years with gas in it, you should completely disassemble the carb and clean it. The float bowl on the VHB is removed by simply unscrewing the 14mm main jet holder on the bottom of the bowl. The bowl should then be loose and detach from the carb body, although I recently encountered one that was very difficult to remove because the bowl o-ring had bonded to the bowl and body, cementing the two together. This is a very simple carburetor and is pretty easy to disassemble and clean. The two needle valves you have already removed are the throttle stop and the idle circuit fuel adjustment screw. The fuel screw should have had a spring, washer and o-ring in the hole you removed the needle valve from. Careful not to lose these parts. The slides on these carbs rarely get stuck in the body but it is possible. If you are able to release the needle clip on the top of the slide and still cannot lift the slide out of the body, soak with lacquer thinner or carb cleaner and work it loose. The slide will eventually free up so you can remove it as long as there is no damage to the carb body that is preventing it from sliding out. Matt

[asmith411]

Thanks Matt,
I disassembled the whole carburetor. There was a lot old gas varnish in the bowl and everywhere. I cleaned and scraped away the crud. Cleaned all the valves and lubed the seats with wd40. I was able to free the slide and extract the main needle that is through the slide. I pulled the pin holding the floats and cleaned them. Are the floats plastic, it didn't appear to be metal?
Are there preset settings for the external needle valves? I would like to have the carburetor set and ready to go when I'm ready to fire up the engine.

Thanks again,
Art

[Nick]

As above, soak ALL metal parts in lacquer thinner for about 30 min. then blast out with compressed air.

[double diamond]

Art,
If there was a lot of varnish build-up inside the float bowl, just cleaning the external surfaces isn’t going to provide the result you hope for. You need to remove the various fuel metering jets and verify that all the drillings are clear. Lacquer thinner may accomplish this but to be absolutely certain all the varnish has been removed you may want to clear the drillings with appropriate size number drills. Also, the internal air/fuel passages in the carb body should be addressed as well. I’ve used aerosol lacquer thinner for this. The Honda brand contact cleaner seems to be basically aerosol lacquer thinner and is useful for this purpose. As far as pre-sets for the needle valves, the idle screw is turned in until you attain the idle speed you desire. This is the screw that protrudes through the slide bore; the slide will rest on this screw when it is at the bottom of its travel. The idle mixture screw can be initially set at 1 ½ turns out from fully closed (do not tighten this screw when turned fully in; you can damage the screw and carb body). Then start the engine, warm to operating temperature and adjust the idle mixture by turning the screw in or out to attain the highest possible idle RPM. When making this adjustment, idle speed should be around 800-1000 RPM. With this adjustment made, set the idle speed where you want it. The VHB floats are plastic; do not soak in carb cleaner or lacquer thinner. Matt

[asmith411]

The carburetor is finished. I cleaned all the valve openings. The idler valve opening was really small, but I was able to get a thin wire through the opening to clean it. Unfortunately, I did soak the float in lacquer thinner. It seems to be ok, the color has changed a bit. I dipped the float in mineral spirits to lubricate it.

The carburetor is back together, ready to install.

Thanks again, I still have the engine to reassemble, so it will be awhile before I test it out.

Art