How to Convert Out-of-Bulb Trash Headlights to “Bulb Replacement”?

Rca01.jpg How to

A sealed beam is, as the name suggests, a component in which the entire headlight housing is integrated with the bulb, and its main feature is that the bulb is not replaceable even if it is damaged. In other words, it is a common knowledge that when the filament is broken, the whole headlight body should be replaced. However, some of the derived models have the same shaped body and replaceable bulbs. If so, isn't it possible to modify it? Please take a look at the whole story of how this was done. This is not a customization that is possible for all sealed beam headlights, but isn't it fun to use such scrap?

If the same body shape is applied, could it work?


In the 1970s, many big motorcycles, especially those developed mainly for export to the US, were equipped with sealed beams as standard equipment. The same was true for the Kawasaki Z1, Mach and Honda CB 400 Four. I had a sealed beam that had run out of bulbs and was no longer usable, so I compared the body shape with the bulb replaceable type and found that they were exactly the same? So it's worth a try, isn't it?

High wattage bulbs can also be used!


A replaceable bulb socket unit that was used in many Japanese models from the late 60s to early 70s and earlier. All manufacturers have this type, and now manufacturers specializing in high performance bulbs are releasing products that support high wattage. I thought, if I can just get this to work and get the optical axis...

Based on the headlight that cannot be used due to cracked lenses.


I had to cut-out the bulb assembly point of the light body whose glass lens was broken by a flying rock, and I was wondering if it would be possible to replicate this cutting technique on the sealed beam body. Don't rush to start cutting out the lens, but first clarify the part that will be the top of the lens, or you may lose the optical axis. Apparently, this body is TOP marked by a small cut-out.

Referring to the bulb hole in the cut-out body


The glass lens was broken by a flying rock, and the bulb socket holder part of the light body was cut out and used as a jig. Can this bring new life to the trashed sealed beam body? Marked the lens rim of the sealed beam body to be processed so that the "TOP" position would not be mistaken. Set the cut-out socket holder part on the bulb part of the sealed beam, and center it while checking the dimensions with a metal tape measure. Adhere the cut-out body for the replacement bulb using double-sided tape for paper with low adhesive strength.

Machining the bulb socket holes as per the markings.


Marking on the sealed beam body to mimic the shape of the notch in the bulb socket area, and reconfirming that the scribble line at the TOP position matches the small notch in a straight line. After marking, I fixed the bulb part of the sealed beam (using a vise) and used a metal saw to gouge off near the base of the bulb. Don't let the body roll away on a cushion or folded blanket and drill the inside of the marking on the bulb socket to make a bumpy hole. Be careful not to proceed with this work too carefully, or the finish will be different later on. If you don't use a sharp drill bit, the hole will slip and the workability will be poor. In this case, I used a new cut Φ2.0mm. I cut off the unnecessary parts with nippers and proceeded to finish filing the bars.

Sealed glass bulb-out of bulb, shatter out.


There are two main types of sealed beams. One is the fully sealed version, in which the gas is sealed in the entire glass body, and the other types in which a thin glass ball covers the filament. Since this sealed beam is the latter, I broke the glass ball that fell into the body with a stick file and took it out. I repeatedly poked it with a stick and broke the glass ball, but be careful not to damage the inside of the lens. The shape of the bulb socket holder was finished by following the marking lines with a small rheuter and a half round bar file. There are also angular concave scrapers, so I need a variety of shapes for my stick files.

The bulb sockets are a perfect match!


If the marking line disappears in the middle of the process, reapply the cut-out sample and rewrite the marking line. If you cut it too much, the fit with the socket will become loose, so process carefully. Check the fit several times before proceeding with the process. By aligning the bulb socket perfectly with the body and turning it quickly, I can see that it is now firmly fixed. To prevent scratches on the glass headlight lens, you may proceed with the work while attaching cloth gummed tape to the front of the lens to protect it.

Use of waste materials with a nice finishing!


I tested the lighting of the headlights. The bulb of this type matched the "PH8 bulb" as represented by the number made by M&H Matsushima. Bright at high wattage, the brightness is unmatched by OEM sealed beams. I installed this modified headlight on the motorycle and brought it to the tester shop for vehicle inspection, and the optical axis and brightness were OK! After that, I was able to pass the vehicle inspection.

  • Point 1. Unnecessary items that are just before being thrown into the trash can sometimes acquire a new life.
  • Point 2. Please understand that this is a work in progress at your own risk.
  • Point 3. If you work well, you can get the perfect optical axis and light intensity. This is exactly how to use waste materials.


When I challenged the user inspection with the sealed beam in place, I couldn't pass due to lack of light intensity. I'm sure there are many Sunday mechanics who have had this experience. There are many reasons why headlights are dim, but one of the most common in older motorcycles is deterioration of the sealed beam bulb. Replacing the headlight with a new sealed beam or a headlight body that can incorporate a high wattage bulb would be a great improvement. However, if it is difficult to obtain new parts for a sealed beam that cannot be bulb replaced, the headlight light intensity can be brightened by installing a booster kit for the headlight.

But couldn't it be simpler to make the bulb brighter? But there are numerous opinions about this, because they don't want to destroy the atmosphere of the motorcycle as an old motorcycle. I have seen a pile of sealed beams that cannot be replaced with bulbs" in a corner of the maintenance area of a store specializing in old motorcycle, and there are many fans who want to be particular about the design and lens cut of the OEM headlights. Indeed, headlights from companies like CIBIE and MARSHALL are stylish, bright and attractive products. However, there are many users who want to brighten up their headlights while still sticking to the standard. In such a situation, I took on the challenge of customizing the headlights by reusing scrap headlights as shown here.

I'm sure there are a lot of mechanics out there who have tried to do a user inspection, but were unable to do due to headlight-related "not allowed" issues. Not just for lower models, but also some relatively older models have recently failed to pass the inspection due to insufficient light intensity.

By having the optical axis and light intensity tested in advance at a preliminary vehicle inspection site (i.e., a "tester shop"), it is possible to ascertain in advance whether or not the motorcycle will pass inspection. In light of the safety standards in Japan, the first step is to install a body with a "lens cut for right side traffic". If a vehicle enters the inspection line with a left-hand traffic headlight body installed, such as the American version, it will not pass the inspection because it will "not produce an optical axis" even if the light quantity is sufficient.

On the other hand, there are cases where the optical axis is well outlined but the light intensity is insufficient. There is a technique to light up the headlights by revving the engine while the headlights are being inspected, but if possible, you want to keep a cool head and pass the test with ease.

There are many cases where a higher wattage bulb is incorporated as a simple way to "increase light output" (e.g., replacing a 50W/50W bulb with a 65W/60W bulb). If the light output still does not increase, suspect that the headlight harness has deteriorated, and install a headlight relay kit (booster kit) that supplies power directly from the battery. There are many examples of harnesses that are more degraded than imagined, and the light intensity is attenuated.

What we are practicing here is a unique example of using waste materials to gain light intensity from the headlights while aiming for a OEM design in terms of appearance. This is not a customization that is applicable to all models, but if you want to brighten up the headlights while sticking to the normal form, you should know that there are examples of such modifications.

Copied title and URL