Serious fork tube repairs - long story

Being a new rider and not wanting to get over my head financially with the purchase of a newer motorcycle I decided to buy an "experienced" 1986 XR 250 R. I'd heard that these bikes were bullet proof and parts seemed easy to find.

After purchasing the bike, I immedately began to make minor repairs such as new wheel bearings, thorough cleaning, and I knew that one of the forks had lost all of it's fluid so I presumed that they needed new seals.

I removed the forks from the bike and took one apart. I had researched some of the videos on the web about fork seal repair and thought I had a fairly good idea about how to do it.

I cleaned the first fork and replaced the seals, and it went as expected. I even made a tool from a piece of all thread and a 20 mm nut welded on the end to remove the dampining system.

My buddy suggested that I clean and prep. the other fork before I completly assembled the first one. This is where the fun began.

After disassembly one of the bushings (lower) was totally destroyed. It was in 6-10 pieces. Well no wonder the seal leaked. After a thorough cleaning and insection I discovered a sizeable dent on the inside of the fork tube about 1/16th of an inch. :ride: It's hard to see but it's at the bottom of the tube. It shows up as a dark dot.


I was sick. I checked with the local motorcycle shop and he immediately said "you need a new fork tube" I knew from some of my research that a new fork tube was expensive. And I didn't really want to spend 1/3 of the purchase price of the bike on one part. So I checked into getting it machined. Nobody could machine the part since the dent was so far inside the tube aproximately in the middle of the tube.

One of the machinists said "why don't you just sand it down" since it is aluminum I thought why not give it a try.

So I went to the hardware store and bought several grits of sand paper. Starting with 60 grit, then 100 grit, then 150, then 200 and finally 400. The 200 & 400 grit paper actually came from a local auto paint store. They gave me several sheets that were from an open packand had been wrinkled.

After attaching the sand paper to a broom handle with contact cement and sanding from most corse to finest grit paper I had it fairly well smoothed out.


I almost forgot. Initially I had the outside dent welded to fill in the hole. The heat pulled the dent out about half of the way making the sanding job a bit easier.


Finally I polished the inside of the tube with two different grades of steel wool to remove any rough places that I may have missed.


After all of my efforts (6-8 hours total) the new bushing were a touch "sticky" at the place where the damage was. But after receiving some words of encouragement from the local MX shop owner I put on new seals, dust covers and fluid in the tube and it seems to be good as new.

After I work out a few more much more minor issues I'll take it for a ride and let you know how it turned out. I have a suspission that I'll need to put new bushings inside the damaged tube much sooner than with a perfect tube but I'm hoping that it will wear in and be just fine for quite some time.

Nice write up. Just goes to show, in these tough economic times, with a little hard work and ingenuity we can all keep riding without spending a ton of money. Nice job!

I'm impressed because being frugal (fancy word for cheap) I perform these kinds of engineering feats more often than I care to admit.

Good job.

How much to buy used fork tube? A for effort and creativity, D for time invested?

How much to buy used fork tube? A for effort and creativity, D for time invested?

Yep, there may be time invested.....BUT every time someone invests a bit of time on problems like this, they learn how to sort them out and gain knowledge that will be applicable to other problems further down the road. You can get a good return on that investment.

How much to buy used fork tube? A for effort and creativity, D for time invested?

D for time invested. Ouch! I thought I was doing fairly good seeing how I needed to manufacture my own tool to take them apart. A new fork tube was $250. I could have purchased a used set, which would have needed seals at a minium for around $100. Basically including the cost of the bushings, seals, dust covers and fork oil, I'm into the fork rebuild about $75.

Good job I like to hear about someone working around a problem and not just throwing money at it.

You did a good job. See how it does when you ride. If it doesn't work out just keep an eye on Ebay. Some thing you need will come up. If you need to rebuild a new set it will go a lot quicker. And thats what makes it a hobby.

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