Fork jump

[rangerguy302]

Has anyone else had a set of forks jump front to rear at interstate speed? Scared the F out of me..... Any ideas on what it could be? I'm benching the battleship till I get it figured out.

[BA80]

Not sure what you mean by "jump front to rear".

[donebysunday]

What is front to rear fork jumping

[JeffH]

You mean like forks oscillating back & forth in the direction of travel?
We're handlebars shaking at all? Or just forks wobbling back and forth?

Tire look round or maybe something internal let go. Everything aok until reach 65-70 mph?

Front Brakes dragging at all? Seem to function ok?

Jeff

[rangerguy302]

It jumped really violently at 80, the forks bent back and forth not side to side. Didn't get a good look at what it was doing at the time.

[BA80]

Have you recently put a different tire on the front?

I had an Avon Venom I couldn't go over 80 with or it got to shaking violently. Put a cheap a$$ Shinko 712 back on and it was fine again.

[rangerguy302]

The only thing I've done to it is put slotted disks in the front and a badly needed break job. No obvious sign of warpage or uneven wear on them, machine stops smooth and is fine till 80mph. Think the wheel bearings might be bad? I know the forks are loose in the respect that they bottom out and clank on the up stroke. Mabe something broke in there. Again no obvious signs of that though. Got me stumped, it's getting colder here anyway. Maybe it's just time to shelf it and rip it apart to the bare frame and look at EVERYTHING.

[BA80]

Try a different tire first. Just for the hell of it. Be sure it's balanced properly too.

[rangerguy302]

Will do, it's about time for a new one. Didn't do it all summer or last with the tire that's on it. Better to be safe, thanks for the advice

[Radioguylogs]

the forks are loose in the respect that they bottom out and clank on the up stroke. Mabe something broke in there.

I wonder if the collar(s) that form the sliding surface inside the front forks is/are broken...or just slipped off and sitting below the inner tube.

[BA80]

Loose steering head bearings?

[rangerguy302]

Steering head is tight, I'm sure it could use a replacement. Far as I can tell they are ok, I greased them good a few months ago and they felt tight. Haven't tore into the forks yet other than an oil change. Is there an exploded view somewhere on the site or a how to? All I've got is my phone to look it up and it won't do the search bar.

[Radioguylogs]

http://www.xs11.com/forum/showthread.php?t=37399

[rangerguy302]

Lol....thanks Mike, not to figgured out how to do an update so I can see the pics😂😂

[donebysunday]

Did you put the bike on the center stand then get something under the engine or frame to lift the front wheel off the ground and spin that front tire/wheel. This is to see if you can duplicate what you had happen on the freeway at 80mph.. An electric drill with a rubber wheel on a chuck (or any thing that will grab the tire) pushed up against the tire might get it to spin fast enough to duplicate the problem (bigger the wheel faster the tire will spin) so you can see what's happening.
I had something like this on the back of a chain drive bike, stopped to check it out and did not see anything, rode another 75 miles and it did it again stopped again nothing seemed out of place. I got home without incident and checked it out real well, low and hold a shiny streak across one of the sprocket bolts. Well that bolt was loose (only one), it was working it's way out until it came in contact with the chain guard bolt. When it came in contact the chain guard bolt it was in just the right position to turn the bolt back in so it would clear for another X amount of miles. Tightened it up checking the others too and all was well.
I was lucky I guess and I'd say you have been really lucky too !
It's much more scary on the front thinking about what could happen if the front stopped turning !!!!!