Fork jump

[rangerguy302]

Tell me about it....I've never had it happen before. I'm going to tear into it and see if I can find the problem. It only seems to do it at speed, I'm wondering if one of the rotors I put on it is out of "flat" on one side. Haven't ridden it much since the install a few months ago. Does anyone know where to get a rebuild for the forks? When I can swing it I'd just soon do it when it's apart, I hate taking stuff apart and putting the old crap back in. It's on the shelf for the season anyway. Can't chance it failing on me at ANY speed.

[txtriathlete]

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.

My thoughts go like this - if something struck the front wheel it could create the deflection you mention. If the front wheel or brake somehow "stuck" (seized) it would do the same. If you have a bolt that somehow interfered with the wheel spin it would do that.

In my mind this is basically like a stick stuck through the spokes - wheel stops spinning (momentarily), friction of tire on road (like slamming on brakes) would push the fork back. If you do this on a bicycle it would flip you over the handlebars. MC is heavier so would lead to a highside or "stoppie" (wheelie in reverse) instead of flipping.

I think I would look carefully at that front wheel and brake. I had a brake come off my oldwing while riding due to loose hardware - that was intense.

[skids]

I think the drilling of the rotors have thrown off the balance of the wheel+tire.

[skids]

I think the drilling of the rotors have thrown off the balance of the wheel+tire.

Oops! Where did I get that you drilled the rotors? Please disregard my previous post.

[Rickrod3]

For me it was a bad caliper

I had an issue with the front forks that would shimmy when going over 75 MPH. It turned out to be one of the front brake calipers was hanging up. I believe it happened gradually. Once the caliper hung up became noticeable, I fixed the caliper and the shimmy problem went away. I install new stainless steel pistons.

[rangerguy302]

😂😂😂Hey skids I thought about doing g that, and came to the conclusion that if they fail....I'm F-ed. I saw some on eBay like that, look them up man they are good for a laugh!!😂😂

[DiverRay]

If the rotors ARE a little out of balance, you should NOT notice it IF the wheel has been balanced. I've drilled the rotors on ALL of my XS11's, for a VERY good reason. When I was riding my first one in '78, in the rain, I went right through a stop sign with both brakes on as hard as I could apply! After that, I took the rotors to a local machine shop and had them drilled so the water could escape. Never had a problem in the rain after that, so I've done it to all my bikes with solid rotors.
The thing to remember is the rotors are HARDENED, and you need a cobalt drill and plenty of oil when drilling them. The machine shop complained that they went through six bits trying to drill the rotors back in '78.