cb650 fork seals – 10 step tutorial

Do your forks leak oil? Mine did. This is about the same on all old 70 honda cb cycles.

* For a complete, exact step-by-step tutorial, consult a real manual. I’m just gonna give the basic steps.

Step 1 – Find a 17mm bolt.
You have to loose the bolt on the top of the fork. It’s a 17mm allen key. Of course no one has 17mm allen keys, so if you can find any 17mm bolt (like the oil drain bolt). You dont wanna use the oil drain bolt because you dont wanna strip it out, so find any other 17mm bolt and grip it up with vice grips as a “make-shift” wrench. Loosen the top two bolts.

Step 2 – Take front wheel off / Loosen the triple tree
This is pretty easy. Take wheel off… Support cycle on milk crate. Once the triple tree bolts are loosened, slide the forks down and off the cycle. You’ll need 2 people for this shit. One person holds the cycle up, while the other person slides 2 milk crates under the head tube. So the cycle is now supported on the center stand, and milk crates.

Step 3 – Forks are off… Now take them apart
This is super easy, just label everything and stay organized as to how the parts come off in sequence. Top comes apart first, then bottom.

Step 4 – Get the fuckin old seals out
This part sucks really bad. The only way Adam and I were able to get the seals out was to grab his torch, and heat up the fork tubes in the spots where the seals sit. Don’t over heat it… Just get it pretty fuckin warm, so the aluminum will expand and you can “pop” the seals out. I used a box wrench wedged under it, and hit it with a hammer until they popped out. Like I said. This part sucked really bad but we eventually got it.

Step 5 – Clean every part of the fork with brake cleaner
Again, this is super easy, just make sure to get all the old oil and gunk off everything. Once every part is clean, lay the parts out on a clean sheet.

Step 6 – Oil everything
I went to the Triumph dealer in manayunk and bought 15W fork oil. The manual called for 10W, but I read online that thicker oil is better for older cycles to help stiffen it up. Anyway, as all the parts are laid out on the clean sheet, with your finger, dip it into the quart of oil and oil every piece.

Step 7 – Reassemble
This is exactly the same as disassembly, but reverse.

Step 8 – Put new seals in
Once the forks are mostly together, slide the new seal over the top tube and down to where they sit in. I used an allen key to gradually push the seal into the area until it finally popped in.

Step 9 – Fill forks with new oil from the top bolt
On my cycle, according to the manual, each fork leg took 5.7oz of new oil. Once each is full, tighten the top bolt up.

Step 10 – Put forks back on the cycle and tighten everything up to spec
This is exactly the same as disassembly, but reverse.

After it’s all said and done my forks feel a little stiffer, plus no more oil leaks out. Pretty cool. Oh, and it took us roughly 5 hours. Not too bad for first time doing it for both of us.

2 responses to “cb650 fork seals – 10 step tutorial”

  1. Alain Goulet says:

    Thanks a lot for publishing this info. I will give it a try on mu ’82 CB 650.

    ps. Do you have anywhere you would reccomend to get a 4 in 1 exaust?



  2. Terry says:

    Hey, Did you only replace the oil seals or did you replace a few other gaskets as well? Mine is also leaking from the top end, left side specifically, and it’s getting oil all over the place. I should probably stop riding it.

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