Repairing Pitted Fork Tubes

[YamadudeXS650C]

The frigid season is truly upon us here in Central New York State, so its time to get wrenching full time.

The first of the bikes to be wheeled into the warm winter workroom is my '73 Yamaha DT3 Enduro "backyard bike".

I replaced the seals in the lower fork tubes last winter, but one of them leaked badly, apparently due to the significant pitting of the upper tubes.

The rusting in the pits is pretty deep, so the usual methods might not be effective. I decided to fill the pits with some sort of compound. I have read that some folks fill them with bondo, but I decided upon my favorite, JB Weld.

Here is an example of what I'm dealing with:

First I used a sharp ice pick to dig out the rust down to clean metal.
Then I cleaned the pits with rubbing alcohol, followed by a burnishing with a small wire wheel dremel attachment.
Alcohol cleaning again.

Applied naval jelly, soaked for 30 minutes. Alcohol cleaning again.
Then I went outside for some fresh air.

After drying thoroughly, I used a razor blade to putty in the JB Weld:

12 hours later, I sanded the excess epoxy first with 800 Wet-or-dry sandpaper using WD 40 (so as to not introduce water), followed by 1200 grit.
It sanded down quickly and easily.

When I was done, with eyes closed I ran my fingers across the pits. The surface was completely smooth.

The shine of the chrome was slightly dulled, and the discoloration of the pits were evident, but heck, its just a backyard bike, and besides, I installed some gaiters to protect the tubes.

Truck gaiters by Daystar, as recommended by 5Twins.

I'll take them apart next winter to check the status of the repair, and I'll report back the results.

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[Jim]

Nice!!

 

[kshansen]

Now if this was a high mileage per year bike I might question it. But if only a playing around in the fields around the house I could see it, if not 100% stopping any leaks, at least keeping it to a minimum.

 

[gggGary]

Cool, hurry up summer!
Might be good to rub some WS2 into the area.
I coat my new fork seals with it.
Can't prove any difference but it makes me feel good.

 

[YamadudeXS650C]

But if only a playing around in the fields around the house I could see it,

I guess I'll just haveta provide a report after 10 years, Ken !

 

[Jim]

Just thinkin' out loud...
J B Weld is pretty durable. As long as all the rust came out and gave a good bond to the epoxy, I think it'll be a good repair even for a daily rider... enough for a season or two anyway.

 

[YamadudeXS650C]

Just thinkin' out loud...
J B Weld is pretty durable. As long as all the rust came out and gave a good bond to the epoxy, I think it'll be a good repair even for a daily rider... enough for a season or two anyway.

Zackly what I'm thinking.
And taking these forks apart is easy as cake.

 

[Jim]

Truck gaiters by Dayco

Gotta link to that particular size Jeff? I'm thinkin' those would look good on my DT.

 

[YamadudeXS650C]

Gotta link to that particular size Jeff? I'm thinkin' those would look good on my DT.

5T has offered us a link previously. I've had these for a year or two.
Lets see if he signs in and provides it again.

BTW, I snipped off three of the sections to make them fit this bike.

 

[YamadudeXS650C]

In regards to chemical resistance, I wanted to make a structural repair to the carb on this DT3 which had a warped surface back in 3/21.
I called the tech department at the JB Weld company, which was a nice gal who was honest with me; she said, "Frankly, we don't test all our products, but if you would like to test it, please give me a ring as to your results."

So, I did the repair,

...and I put a chunk of hardened JB Weld into gasoline, and have checked it regularly. It is still fully intact today.

And the carb doesnt leak.
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[Sparkyduc]

Cool, hurry up summer!
Might be good to rub some WS2 into the area.
I coat my new fork seals with it.
Can't prove any difference but it makes me feel good.

WS2? What are you referring to Gary.

 

[YamadudeXS650C]

.. and a chunk of JB Weld is going into a jar of ATF, which is what I put into these fork. I had a gallon sitting around on my shelf.

 

[SEd27]

It should be fine. I did a similar fix on the XS fork tubes about 10 years ago.

Never had any issues.

 

[DogBunny]

FWIW:
I tried the same JB Weld repair on a pitted '77 and later brake caliper piston. I think they are similar materials with similar finish? I think I did a pretty good prep job, although not as thorough as you did. Anyways, it was a complete failure, so much so that I never even installed it.

 

[Jim]

FWIW:
I tried the same JB Weld repair on a pitted '77 and later brake caliper piston. I think they are similar materials with similar finish? I think I did a pretty good prep job, although not as thorough as you did. Anyways, it was a complete failure, so much so that I never even installed it.

Was it exposed to brake fluid after the repair?

 

[Mailman]

Nice repair Jeff! That sure ought to work very well, a great way to save old forks especially if you can cover the repair with gators, as you did!

 

[5twins]

The fork boots I use are the Daystar brand .....

Here's the part number for the black ones .....

Google "Daystar KU20002" and you'll get lots of hits. I've had some of these installed for over 20 years and never had one go bad or wear out yet.

 

[gggGary]

WS2? What are you referring to Gary.

Short for Tungsten disulfide, it's a lubrication powder.
A thread on it here; https://www.xs650.com/threads/tungsten-disulfide-lubricant-anyone-mess-with-it.51149/

 

[kshansen]

Not sure of ATF and JB Weld but I have used JB Weld to reattach the magnets for the alternator in my 1988 Sportster. These run in the transmission oil and have been in there since 2009 and last I knew they were still holding!

 

[5twins]

I used it to repair a leaking petcock on my '78 probably a good 10 years ago and it's still holding up fine. I'd have to say the stuff is definitely fuel resistant.