Fork questions and general confusion, GS450 ET

[Nessism]

The fork oil level is not critical, I think some of you guys are over thinking this. As long as the damper rod is covered the damping will be there. The other thing the oil level controls is the amount of air trapped inside the forks. When the forks are compressing this air is compressed, which provides a little anti-bottoming assistance.

I'd fill the forks to 5.5" from the top with the springs removed and the forks compressed. This works or the larger GS's, and will work for the 450 too.

[apopleptic]

The fork oil level is not critical, I think some of you guys are over thinking this. As long as the damper rod is covered the damping will be there. The other thing the oil level controls is the amount of air trapped inside the forks. When the forks are compressing this air is compressed, which provides a little anti-bottoming assistance.

I'd fill the forks to 5.5" from the top with the springs removed and the forks compressed. This works or the larger GS's, and will work for the 450 too.

Is the info I have correct in stating that it's more important that the fork oil be level in both forks versus exactly how much there is?
I was told uneven level will make the fork compress unevenly making the front wheel kind of twist under hard braking.

[pete]

The fork oil level is not critical, I think some of you guys are over thinking this. As long as the damper rod is covered the damping will be there. The other thing the oil level controls is the amount of air trapped inside the forks. When the forks are compressing this air is compressed, which provides a little anti-bottoming assistance.

I'd fill the forks to 5.5" from the top with the springs removed and the forks compressed. This works or the larger GS's, and will work for the 450 too.

Makes sense Ed, and you should know by now I tend to over think things

Thanks for the tip, I'm just working the measuring technique out at the moment actually

Is the info I have correct in stating that it's more important that the fork oil be level in both forks versus exactly how much there is?
I was told uneven level will make the fork compress unevenly making the front wheel kind of twist under hard braking.

Yup, for sure.

While there are modern bikes that have rebound damping in one leg and compression damping in the other, the forks are designed for it.

In these old GS' I reckon you'd need one hell of a good fork brace to be able to cope with uneven oil levels...

[bccap]

The measuring is easy. Just take the pump off an old shampoo bottle, or even a windex bottle. Pump is better because you don't have to hold up a container to catch the spray. Cut the tube 5.5 inches from the bottom of the cap. Fill up the fork til it looks like four or five inches from the top. Stick the tube down the fork and pump out til your sucking air. Repeat on the other fork and you'll have perfectly level forks.

[Trevor76]

I did it today, got an unexpected bit of free time and ran to the garage. Basically I filled an empty (and rinsed out) shampoo bottle with 5oz of 10w-30 oil, and 5oz of ATF. Then I shook it up. I then measured (roughly) 4.9 oz of the mixture and poured it down each fork tube -spring out, fully compressed. I then used the spray bottle pump-thingy method, with the tube cut off to exactly 197mm. I must've done it right because it only took a few squirts in each tube to empty the pump. Re-assembled and ready to go back on the bike.

By the way, a pair of Honda cb350 fork gaiters work perfectly for the GS450, pics tonight if I have insomnia after work, or tommorow...

Speaking of work I gotta run, thanks again for all of the help and insight.

[pete]

Good stuff! Glad to hear it

[Jagir]

The measuring is easy. Just take the pump off an old shampoo bottle, or even a windex bottle. Pump is better because you don't have to hold up a container to catch the spray. Cut the tube 5.5 inches from the bottom of the cap. Fill up the fork til it looks like four or five inches from the top. Stick the tube down the fork and pump out til your sucking air. Repeat on the other fork and you'll have perfectly level forks.

Consider adding this to the "tips and tricks" forum, it's a good one.

[Matchless]

The measuring is easy. Just take the pump off an old shampoo bottle, or even a windex bottle. Pump is better because you don't have to hold up a container to catch the spray. Cut the tube 5.5 inches from the bottom of the cap. Fill up the fork til it looks like four or five inches from the top. Stick the tube down the fork and pump out til your sucking air. Repeat on the other fork and you'll have perfectly level forks.

Thanks for that tip! Where were you when I did mine?
I have added it to my tutorial and will send BassCliff an update for his library soon.

[Nessism]

Did you pump the forks a few times after you added the oil? You have to pump them to get all the air out of the damping passages before measuring the height.

[BassCliff]

Hi,

See: Fork Seal Replacement and Install Progressive Fork Springs (PDF files).






Thank you for your indulgence,

BassCliff