harleyKmodel

I have a Linkert DC12 that has no end cap on the bottom of the idle tube. Does the bottom of the idle tube need to be sealed with the end cap? The carb was on a running bike which was put away back in 1979. There was nothing to suggest it wasn’t running. I noticed the lack of end cap when I dissembled the carb to clean it. The cap hadn’t fallen into the fitting around the spring . Plugging it wouldn’t be a problem but I was wondering if the end cap might have been removed for a reason.

Its been awhile since I looked and Others may know better, but I believe that the cap serves as a surface for the spring to push against. I don't have an open carburetor in front of me and my memory isn't what it used to be, but the cap might also act as a seal, thereby allowing the tube to draw form its top only, but without looking, I may be incorrect on that point.

I’m not sure if this might be performance mod or something. The bike was raced before it went into storage. I got it from the original owner and everything else seems to be what you’d expect on a 60 year old one owner.
I can’t seem to get in contact with Mike at Into The Wilderness, he’d know.
But as I see it , if it doesn’t need to be plugged, that’s fine, but if it does, not a big challenge. I figure a drop of solder would do it.

Talked to Mike at ITW. Yes- the idle tube has to be sealed at the bottom for an idle. According to him there aren’t any replacements in the known universe. But the fix was relatively easy. I took a very small brass brad, cut it down ( the pin hole in the lower part of the tube has to be clear), dressed the shaft to size and soldered it in. Dressed the solder and reinstalled it. Here’s hoping. For reference, the i.d. Of the tube is .058, o.d. Is .076 and the spring well in the fitting is .115. What happened to the end cap is still a mystery .

Looks like you properly solved the problem. I've seen them without the end cap as well. It sometimes comes off then you try to remove a tight fitting tube and flies away. Don't ask how I know this......
I actually fabricated an Idle tube for my '64 CH. It was time-consuming and now, after being completely restored 9 months, I still haven't started the bike (long story). SO I don't know how well it'll work (but I'm quite confident).
Probably a good market for someone willing to fabricate the tubes in a reasonable quantity!

The main thing was being sure the solder adhered. It’s a brass to brass joint so it should be solid. It shouldn’t be a big production to make up replacement tubes, the tubing must be a stock item somewhere.