The International CBX Owners Association

No worries, this is not an engine oil question

I am rebuilding my forks and was wondering what weight oil everyone is using. FSM says ATF oil, but I assume there are better things out there!

ATF is nominally equivalent to 10W fork oil. I am #230 and prefer 15W oil, at 140mm (EDITED) air gap - measured with the fork collapsed and the springs removed, 10w will be plusher, 15w better damped.

I think you meant 140 mm.

247 ml of fork oil will get you real close to 140 mm on a twin shock.

My method (works super in my 79 750F with 35 mm tubes, 81 900F and 82 CBX with 39 mm tubes) is 15 weight fork oil (I weigh 230 +/-) filled to 6 inches (150 mm) from the top of the tube, with the spring removed and the tube completely sacked (gently of course) into the leg. I overfill the tube, then use a suction device (turkey baster / miti-vac / .....) to suck out fluid down to 6 inch level.
Freddie Spencer I am not, but I love a spirited ride.

Steve

Thanks everyone. I didn't mention it (and just updated my signature) I have the 1980 model with the air forks. Will dig into that soon, but my charging system gave up on me today, so not sure where to start first....

Fixed my chanrging issues anf started digging into the forks. I had some issues getting the bottom bolt out of one fork leg, it was just spinning and the damper was turning. Blocked the bolt with a small screw driver and drilled it out, not what I had planned but it worked!

oroepke wrote: ↑

Tue Mar 28, 2023 12:56 pm

Fixed my chanrging issues anf started digging into the forks. I had some issues getting the bottom bolt out of one fork leg, it was just spinning and the damper was turning. Blocked the bolt with a small screw driver and drilled it out, not what I had planned but it worked!

Next time just invert the (assembled) fork assembly, with a plug in your air cap orifice, and bump the damper rod bolt with a cordless impact to loosen. Turn the bolt back in by hand just enough to prevent making a mess and then disassemble as normal.

N.

I'll add that once you get the damper bolts out, chase the bolt and damper threads so re-assembly goes smoothly, and future disassembly does as well.

Dave

Noblehops, I had first tried just with an Allen wrench and it started turning and only after that I used the impact driver. I think if I had started right away with the impact driver it may have worked. Lucklily, drilling it out was not too big of a problem.

Good advice, Dave.

The thing that has worked for me on a couple of stubborn ones that even an impact wouldn't loosen, is to clamp the assembled fork leg horizontally in a vice. You have spring pressure obviously, but now lean heavily on the fork lower to compress the spring as much as possible, then zap it with the impact. Worth a try before drilling.

Dave

daves79x wrote: ↑

Wed Mar 29, 2023 2:08 pm

The thing that has worked for me on a couple of stubborn ones that even an impact wouldn't loosen, is to clamp the assembled fork leg horizontally in a vice. You have spring pressure obviously, but now lean heavily on the fork lower to compress the spring as much as possible, then zap it with the impact. Worth a try before drilling.

Dave

I have tried that too, but my mistake was that I tried with an Allen wrench first and the damper had started spinning inside the forks already. I have the feeling that if it hadn't moved first, it could have worked. I left the other leg installed in the tripe tree and hit if from below with the impact, pushing up pretty hard. No problem, came out easily. Lesson learned I guess!