Repairing hard-to-find front fork inner tubes with re-plating

The late 1970s to the 1980s saw various models released by every motorcycle manufacturer. It was truly the height of the "motorcycle boom"!! Because of this, it is known that a wide variety of models were released one after another. Conversely, this means that repair parts for many of these models are now difficult to obtain. Here, we disassemble and repair the front fork of the Honda XL250S, an off-road bike iconic for its "23-inch front wheel." Since the inner tubes are hard to find, we decided to repair them by finishing them with recycled hard chrome plating.

The Honda XL250S with its 23-inch front wheel, which captured the hearts of off-road fans with its stable ride

The maintenance vehicle is an early model of the Honda XL250S, which debuted as a 1978 model. The design of the resin meter was somewhat reminiscent of a keyhole-shaped burial mound. The handling of the 23-inch front wheel was stability-oriented, and it boasted overwhelming popularity among touring riders who were fans of off-road bikes.

"Recycled hard chrome plating" finish that shines brighter than new parts

A precision control sheet comparing the condition at the time of the request (order) and the finished state (before delivery) is also attached, providing peace of mind. After the tube's straightness is inspected and corrected, it is cylindrically ground until the rust is gone, and then recycled plating is applied.

Immediately after recycled hard chrome plating, it finishes in a matte silver, but it is precision polished within the plating film thickness to shine brilliantly. The edges are also thoroughly polished, leaving no burrs at all. This finish is wonderful!!

Cooperation/Toyo Koka www.toyokoka.com

The structure is simple, and we solved the lack of tools with an idea

The inner tubes were in a condition that could have been used even with hand polishing. However, there were several pinhole rust spots around the stem clamp area, and the plating layer was thin and lacked luster, so we decided to revive them with recycled hard chrome plating.

The front fork top bolt was a 17mm hexagon socket type. I didn't have the tool on hand to loosen it, but an M10 long nut I bought at a home improvement store looked like it could be used as a wrench!?

The M10 long nut I bought at the home improvement store's bolt section worked. Since the width across flats is 17mm, if I use this with a reverse way of thinking, I can loosen the top nut. I used the long nut as an adapter.

There was no oil leakage, so the inner tubes contained almost the specified amount of fork damper oil. I removed the spacer washer and spring, and drained the fork oil. It had the unpleasant smell of degraded oil.

I pushed the inner tube to full bottom, pressed a long T-wrench against the top of the inner part's seat pipe, and loosened the bottom bolt while holding the damper pipe so it wouldn't rotate. If it spins together, use an impact wrench.

Once the bottom bolt is loosened, turn the fork body upside down and pull the seat damper pipe out from inside the inner tube. In the case of high-mileage vehicles, the resin piston ring may be worn, so you should replace it in such cases.

Use a dedicated SST to remove the bottom case oil seal

Use a dedicated puller to remove the oil seal driven into the bottom case. In this model, the oil seal was deep and difficult to remove. Be careful not to scratch the seal press-fit seat (inner wall of the bottom case).

I was glad I could purchase genuine new parts during the work, but if parts supply had ended, I would have dealt with it using aftermarket parts. Oil seals with matching dimensions should be available from multiple oil seal manufacturers.

I worked carefully to avoid scratches, but scratches from previous maintenance remained. I used a rotary tool to remove the burrs from the scratches. If you assemble it with the scratches and unevenness as they are, it will cause oil leaks and seepage.

Sunday mechanics should own various oil seal pullers

Various tools used to disassemble the front fork. The 17mm long nut is useful in various situations, not just for front forks. A long T-wrench is convenient when the damper seat pipe spins together.

The finish by a polishing professional is completely different; the "mellow finish" is beautiful

I ordered the genuine-style mellow finish from Negishi Kenma, a professional buffing shop. It's not a part that I couldn't polish myself, but uneven shine is likely the work of an amateur. As expected, the professional finish is wonderful!!

Cooperation/Negishi Kenma www.neken.co.jp

The motorcycle I was entrusted with, with the note "Please repair it if you can...", was the Honda XL250S, known for its 23-inch front wheel. When I first received the vehicle, the inner tubes looked to be in good condition, so I was optimistic, thinking, "Maybe I can get by with just polishing?" However, when I removed the front wheel and the front fender, I discovered several pinhole rust spots around the steering stem (under bracket) and top bridge tightening areas. It looked like it would be surprisingly noticeable after repair. It may be that the rust is in a place that is not functionally problematic, but having the plating on the inner tubes shine deeply makes the bike look beautiful, and that was the owner's request for the finish. If that's the case, I have no choice but to request recycled hard chrome plating.

While the manufacturer's genuine hard chrome plating gives the impression of being thin due to cost-cutting (especially for models from the late 70s to the 80s), recycled hard chrome plating has a high-quality texture and can be finished to a mirror-like shine with surprising brilliance and luster.

I requested the recycled hard chrome plating from Toyo Koka in Kurume City, Fukuoka Prefecture. The finish is simply outstanding!! Unlike decorative plating, recycled hard chrome plating, which is finished under precise dimensional control (in 1/1000 mm units), is a beauty that surprises everyone who sees the delivered parts. Before starting the recycling work, the inner tubes are reliably inspected and corrected for straightness, so you can request it with peace of mind. As mentioned above, unlike manufacturer genuine inner tubes that prioritize cost, it has the characteristic of being less prone to rust after recycling because the plating film thickness is secured.

At the same time as the front fork disassembly, I requested buffing for the bottom cases, which had advanced aluminum corrosion, from Negishi Kenma. In the past, shiny mirror finishes were popular, but they are not currently, and a "mellow finish" similar to the manufacturer's genuine finish is popular, so I requested that mellow finish. Now that the inner tubes and bottom cases are finished, I am looking forward to the assembly work ahead.