VM Carb Choke Pickup Tube Replacement

[OldPainless]

Not sure if this was covered before but... here it goes.

Had 4x cracked choke pickup tubes on my 77 GS550 carbs. Was annoyed, because I had acquired a 500 mile bike and was hoping it'd be in better condition. I saw a modeling video on YT and thought - that's some really small brass tube. 5 minutes on Amazon found a pack of 3mm OD x 2.5mm ID tube and some 2.5mm OD brass rods. Tossed in a micro drill set and... a few bucks later... I was making my own VM replacement brass parts.

So, I cut the tube to length 32.5mm (I think) and soldered in a piece of the rod for a plug. Cut off the rod and bam - tube with a plug. 5 min with the micro drill and I had this.

I have to say - it's the same length and diameter as the original. The wall thickness is NOT the same but I didn't find any replacement bits, so I feel pretty good about my first go at homemade carb parts. I'll report back on how it works once I get everything put back together.

 

[OldPainless]

And a shot in the carb.

 

[Nessism]

Nice work. Your carbs have a chalky scale on them, but the choke tubes look nice!

 

[OldPainless]

Yeah - anything I can do about the chalkiness? One is really bad looking.

 

[Nessism]

did you soak the carbs in carb dip? That may help if you haven't. I use cheap wire brushes as sold by places like Amazon, in a dremel. That won't clean the interior passages, but at least you won't have the crud in the float bowls.

 

[OldPainless]

Awesome. I stopped using carb dip a while back in favor of using my sonic cleaner with aluminum safe simplegreen. I'll get some carb dip and wire brushes.

 

[chuck hahn]

All you need to do for cracked tubes or overflows is simply flux and solder the seams.

 

[Nessism]

All you need to do for cracked tubes or overflows is simply flux and solder the seams.

Sorry, chuck, but I disagree. Replacing them is far better.

 

[chuck hahn]

Soldering hurts nothing. Reseal the seam and be done with it forever

 

[OldPainless]

Except when you go to solder it and they crumble away...

Tried that first. Wouldn't be engineering a solution this elaborate if the obvious worked. Plus - it gives me something to do.

 

[chuck hahn]

Well yeah but i didnt gather that detail from the post. As for the chalky scale. Iwould try soaking one in 8 percent cleaning vinegar.That might eat it away. I also have used those wire brushes for y Dremel to scrub them..Sometimes even that doesnt get it all but it will get anything that could flake off gone for sure

 

[Nessism]

Keihin carb overflow tubes commonly split. I messed around with soldering, but wasn't happy with how it was turning out, so I taught myself how to replace the tubes. The biggest challenge was flaring the OD of the tube, so the press fit will seal. I took a drill bit of appropriate size, ground a taper into the butt end of the bit, and inserted it into the piece of brass tubing I found, using a drill motor. I also rolled over the end of the tube using the dimple in a threading die. This part didn't work out perfectly, though. At any rate, I've done at least a dozen bowls this way now with good results.

P1030567 by nessism, on Flickr

 

[chuck hahn]

I have replaced those without flairing the tubing. I put some tank sealer on the tube and spun it around to distribute the sauce. Dozens of ways to skin the cat.