Fork seal leak

[Guth_imp]

I've heard that Aprilia's parent company Piaggio is an unbelievable pain when it come to dealer support, especially parts supply. (I was informed of this by my local Aprilia dealer.)

[Jim21680_imp]

Regarding fork seal failures...what exactly happens when this occurs? Does the fork lose compression and gradually lower the front end? Or does it just lose all it's damping ability, etc?

I'm only curious about the consequences: If you're out on a ride, far from home, can you continue to ride the bike?

[the Ferret]

Jim, a bikes front end is held up by the springs, so it won't collapse. Loss of oil changes the damping on the bike, and a leaking fork seal generally makes a mess of the right fork leg. When the front end is compressed the oil is forced thru tiny holes in the damper rod, as the fork decompresses the oil is drained back thru the holes in the damper rod. I believe I am explaining that right. The spring and air inside the tube controls the compression and the amount of oil, the weight of the oil, and the size and number of holes in the damper rod control the damping.

I'm sure someone much smarter and an engineering background will be along to correct me shortly lol.

Here ya go, found this which may explain everything better than I did

http://racetech.com/HTML_FILES/DampingRodForks.HTML

[shdwghst457_imp]

The bigger concern for me was that it was leaking right onto the brake disc, which would have effectively cut my braking power in half (fortunately this is a dual-disc bike, my Shadow wouldn't have been so lucky...) Mostly I'm just glad I took the bike in to get that accessory removed, who knows when I would have noticed the leak. Very glad to have it back. It's scary to think that there are more powerful bikes out there than this one. 60 in 3.3 seconds is beyond enough for me!

[the Ferret]

Lol there are bikes out there so much more powerful than this it is almost inconceivable how someone can ride one not on a racetrack. Once they got over 125 horsepower they were effectively too powerful for me. There are some now approaching 200 horsepower. Street bikes. That is insane. Luckily they are all speed limited to only 186 mph

[Deanohh_imp]

Lol there are bikes out there so much more powerful than this it is almost inconceivable how someone can ride one not on a racetrack. Once they got over 125 horsepower they were effectively too powerful for me. There are some now approaching 200 horsepower. Street bikes. That is insane. Luckily they are all speed limited to only 186 mph

yeah, those old Busas that would go 192 were pure insanity. What a relief that it was brought down to 186.

[shdwghst457_imp]

According to this page the CB1100 is plenty fast
https://en.wikipedia.org/wiki/List_of_fa...celeration

Although our bike hasn't been added to this page yet. We're at 3.3 seconds to 60 and 11.79 in the quarter mile!

[flynrider]

Regarding fork seal failures...what exactly happens when this occurs? Does the fork lose compression and gradually lower the front end? Or does it just lose all it's damping ability, etc?

I'm only curious about the consequences: If you're out on a ride, far from home, can you continue to ride the bike?

In the vast majority of cases, seal leaks develop gradually. In those cases you can continue to ride, just make sure it's not leaking on the brake.

A few years ago I made a dumb mistake and installed some lower windshield supports too low on my cb750s fork legs. They were fine with just me on the bike, but when I loaded all my gear for a 3500 mile camping/road trip, the front suspension compressed way more than usual under heavy braking. About 500 mi. into the trip, the lower windshield clamps had punched right through the seals. Doh!

I finished the last 3K miles with leaking seals. Handling was still OK. When I finally got around to replacing the seals another thousand or so miles later, there was still 3/4 of the fork oil remaining.

The worst part about leaking seals is the mess.

Pipes covered with burnt fork oil


Lower fork covered with oil


I even had fork oil on the fuel tank


Here's what a pair of jeans looked like after a few days on the highway.

[the Ferret]

Yuk

All my jeans looked like that when I rode my BSA 750 triple

[Red Mist_imp]

Lol there are bikes out there so much more powerful than this it is almost inconceivable how someone can ride one not on a racetrack. Once they got over 125 horsepower they were effectively too powerful for me. There are some now approaching 200 horsepower. Street bikes. That is insane. Luckily they are all speed limited to only 186 mph

yeah, those old Busas that would go 192 were pure insanity. What a relief that it was brought down to 186.

yeah, those old Busas that would go 192 were pure insanity. What a relief that it was brought down to 186. Yes, we can all rest easy now.

Agree, 125 is about the limit for any sane street riding. Modern superbikes may claim more but the computer won't give it to you in the real world, except maybe in a straight line, to some limited degree.

These days you can buy far more motor than anyone can use, and the computer takes over when your skill runs out.

You hope.