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So I finally got off my lazy arse and carefully engineered a carb ballancer out of some clear tubing and 40w oil. Tried it out on my R75/2 convertion and it works great. Got it real nice and smooth in about two minutes.

I was so excited, I rolled my 72 R75/5 into the shop and went to hook it up and there where no vacume ports. Both bikes have 9/10 carbs on them, but I never noticed that one set is "sans de ports".

So now I have to make some. My plan is to take a couple of short lengths of 3/16 steel brake line and tap the inside to take a 6/32 screw to block off when not in use. Then I need to drill the carbs to take the tubing. I have a ported set of carbs to uses as a sample for the drilling.

Now for the hard part, how do I fasten the steel tubes into the carb bodies?
I can think of three options:

1; Press fit by heating the carb body and freezing the tube.

2: Thread the outside of the tube and tapp the carb body and use a little dab of Loctite.

3: Good old JB Weld.

What do you'all think.

I think, brace yourself Garnet. Duane's going to come across your post and ask why you're trying to do something that can be done better and faster by ear.

He would be right. I've seen him do it. But lest I sound holier-than-thou I'll cowboy up and admit that I have used the gauges myself.


But aside from the Duane warning, how about buying another set of carbs from a later model? I've heard (probably from Duane) that the early /5 carbs were problematic and that later carbs are better.



Ken

I've been doing it by ear forever and eventually get it right. The two or three times I've borrowed a mamometer I"ve got them REAL close in just a minuet or two, so I invested over $7 on this project.

I knew the very first CVs had isues but I thoght that by the time the 9/10s came along those problems where delt with. Besides I'm sure you want me to take a pair of functional carbs over to the drill press and then throw them in the oven.

What could possibly go wrong.

Airbear should be along soon as he uses tubing and oil to balance himself too.

There's actually two different "standard" metric motorcycle vacuum fitting threads: 5mm and 6mm.

If you're going to go to the trouble of drilling and tapping, might as well go ahead and tap it to take one of those two standard fittings.

my /6 has 9/10 carbs it came with ports from the factory

The correct part exists - they are a small hose barb with a coarse self tapping thread .

There was one in the fitting kit for my vacuum operated " Scottoiler " to enable a vacuum connection to the manifold if the bike didn't have one.

One day I will fit it to the bottom of the paralever with a bit of clear tube running up to the top of the paralever , so I have an early warning if the paralever starts to fill with oil.

Bing sells or did sell a kit with the spigots that have a washer and blank off screw. The instructions provide the drill size required.

Tim