R50/5 "Remove throttle slide"

[audiowize]

So, I'm getting everything loose on my carbs in preparation for a rebuild, and I can't for the life of me figure out how to remove the throttle slides (I have the early Bing slide carbs).

I have the knurled nut on the top of each carb popped off, and I've brought as much slack into the throttle cable as it will allow, and I guess I was expecting the relief of the spring pressure to be what allowed the slide to pop out.

Any advice?

[Duane Ausherman]

The slide is stuck in the carb body. Corrosion from humidity in the air jambs them up. You will see it as a white powder.

Try soaking some light oil around the top of the slide. WD 40 will work, but there are better ones out there. Then let it sit for a day or so. You might keep adding to the slide, just a drop or two at a time. Remove the carb air intake tubes and use something plastic, or wood to gently pry up on the slide. You might need to use a hair dryer to add a bit of heat.

[sterob]

What Duane said and 'gently, gently....':0)

[audiowize]

Thanks for the info guys! I did soak the slider down overnight with penetrating oil, and I'll go at it again over the weekend.

At worst, I suppose I can dip the whole carb into the ultrasonic tank and just zip tie the cable up and out of the way.

[Duane Ausherman]

Be very careful what chemical that you use to soak a carb, as some have come back to find almost nothing left. I never had an ultrasonic tank for this issue. It was never that badly stuck. Let us know what works out.

[Ken in Oklahoma]

Be very careful what chemical that you use to soak a carb, as some have come back to find almost nothing left. I never had an ultrasonic tank for this issue. It was never that badly stuck. Let us know what works out.

I too would be very cautious about soaking a carb, ultrasonic or not. One of my airheads had carbs that were soaked in something, and obviously left to soak for a long while. Those particular Bing carbs had a plate riveted onto the side and that plastic was badly deformed. I'm thinking it could have only been done "soaking" the carb.

Ultrasonic, or not, I would be very skeptical of any "agitated" fluid being able to successfully penetrate a tight crevice, such as the fit of a slide into a carb body. The slide gets stuck likely because of moisture enhancing the tendency of metals, such as carb bodies, to oxidize. And the oxidation expands and takes up space, which is what made things "stuck". Similarly I'm skeptical about agitated fluid being able to get into fine orifices with any agitation happening. It doesn't take much crud to gum up an orifice.

One time a "nameless" fellow came to a Boxerworks rally at my place. He drove the whole way with his bike performing badly at idle and off idle. He took a carb off of one of my project bikes and put it on his and his problem was gone--of course. Encouraged he went to work on his carb in my shop with me and Larry Fixit "supervising". One thing I wanted to make sure of is that all orifices were cleared, as evidenced by carb cleaner spray coming out where it should. (If you don't know where all those little drillings go you can figure it out by examining the carb itself, noting the casting lumbs and bumps which had to be drilled and plugs that were put into place after the drilling. Plus the Bing site used to (and probably still does) have a schematic drawing of the orifices in the carb.

Ken

[audiowize]

Yeah, my study of physics was limited enough that I don't have a feel for the necessary conditions for cavitation in a fluid. I did another squirt of penetrating oil this morning, and tomorrow morning I will go ahead and yank off the air tubes and try some prying.

I've also had good luck with heat working in situations like this in the past, and I have a decent heat gun and a propane torch at the ready, but I'd rather not risk melting anything.

[Duane Ausherman]

Add the heat very carefully and slowly. Never consider a propane torch on a carb. I wouldn't take it above boiling temp. Then add more oil and gently pry it again. That metal is very soft and easily bent, dented or broken.

Most things on a BMW require a soft touch. Rarely do we use a hammer. It isn't a HD.

[ME 109]

Rarely do we use a hammer

It's not the hammer, it's the swinger.

[Duane Ausherman]

ME 109 said, "It's not the hammer, it's the swinger."

I ain't no swinger, that is my sister.