Setting up the Headset

Well, I think it’s been 3 months since I sent the headset off to the painter. I got it back the other day and it looks really good. The problem is that my scooter is almost 40 years old and it has years of patina on it. I’m not sure what to do about that but get the ol’scoot out on the road and get the headset covered in road grime.

Of course, there’s still a little bit of work to do before I can ride so let’s get down to it, shall we?

Like I said, the painter did a great job. On the old headset, the dimple that indicates the gear selected has had the paint chipped out and the new one is white. Anyone know if it should match?

I’m working on a “do things as it needs to be done” basis so there isn’t always a method to my madness. The new headset look like it had been stored outside for a long time and had a bit of corrosion on it. The threads on the underside, where the mirrors or (gasp) windshield might go were pretty rough. Then they got painted.

Step one was to chase them with a tap to get ‘em back in shape. ThisĀ is step one, since step two requires them. More after the photo.

If you’ve taken the time to read through the thread then you know that the throttle tubes were so stuck that I had to cut them out. Well a couple of screws were also so corroded that I couldn’t get them out. I don’t ordinarily have some of the shop tools around that would be useful to extract such things, so they didn’t get taken care of before going to the painter. Now that I have a nice finish, I need to tackle some stuff that isn’t necessarily good for a new paint job. Let’s see if I can get this done without scratching anything.

I fabricated a crude but very effective jig to get the headset under the drill press that I borrowed from one of my friends. You can’t really tell in this picture, but there’s stacks of washers under the wood to get it to the proper alignment under the drill. The nice thing about the soft wood was that I could torque the screws a bit more or less to fine tune it once it was clamped down.

Then, I pulled out a very very small drill bit and went right. down. the. center. of the stuck screw. You are looking at the M3 .5 pitch screw that holds the right switchgear to the headset (with a hole in it.)

The stress level in the garage was high. There was coffee, there was beer, and there was soothing music.

So this one is kind of a no-win. I want to get the screw out without damaging the hole. But I don’t have a mill and the accuracy that comes with it. All I’ve got is this borrowed bench-top drill press which has just enough run out to make the effort of drilling the screw and salvaging the threads in the hole an exercise in futility. Besides, I only have an M3 .7 pitch tap, so I can’t chase it, or re-tap it once the screw is out.

Here’s where reality checks in. How much perfection am I willing to sacrifice to get this scooter back on the road? Well, the going thought is that I’m trying to keep it as close to original but still be rideable. That’s it really, I want to ride this thing.

So I bust out the #30 drill bit, drill out the old screw and overbore the hole in one pull. Then I tapped the hole for an M4 .7 pitch screw.

Checking the threads with a dummy screw. I’ll find a proper machine screw for it later.

Carbureting!

Today I got into the carburetor.

Got a few out-o-focus pics here, sorry.

Carb:

Oiler:

Lucky for me, the gasket came off with the oiler. I was afraid that it would tear and I’d have to make a new one by tracing it onto a piece of generic gasket material. While I wouldn’t ordinarily put an old gasket back onto anything, this time I’m making an exception. I can’t find a new one anywhere!

Notice the etched “h”? I have no idea what that means.

Empty box:

Side note:

I’ve never been into a 2-smoke engine before and the finer details make me very curious. I’ve got the theory down, but I like to see stuff for myself. The rotary valve intake? Here it is!

Closed:

Open:

The nice thing about the rotary valve, is that you can use the kick starter to close it and prevent yourself from dropping any parts into that case. I put a rag in there anyway.

So once the carburetor box was off and the area was cleaned of debris, I used a pick to catch the inside edge of the brass sleeve holding the auto-oiler’s shaft in place. I tried lifting it with a magnetic parts grabber, but it wasn’t strong enough.

It pulled right out:

The oiler is ingenious. I spent a good 15 minutes inspecting it and figuring out how it works. Brilliant! The throttle position moves a ring inside the housing, and then another little ring and piston pump the oil. As the throttle moves, the ring moves making the little pump move more oil. Clearly, as RPM’s increase, so also does the oil flow. To keep a constant 2%, it compensates for both engine speed and throttle position.

I. Love. It.

Then, I used the assorted parts that came in the gasket kit to rebuild the carb. After 36 years, it was still clean inside. Seriously, there’s nothing to report. No varnish, no grime. Perfectly clean. I dosed it all with carb cleaner anyway and then put it back together with new the new float, needle, and gaskets.

Once I find an o-ring to fit between the oiler sleeve and case, I’ll put it all back together.