76 KZ750 B1 Twin

Thanks again Doc. Where did you get the rotors with the purdy drill pattern? I checked the FSM and spec for runout is under 0.1mm and the service limit is 0.3mm. Those things really want to be flat it seems.

They can drill what ever pattern you like when you get them ground. I had him copy the hole pattern in my ISR disks

Been pondering my front braking issue some more and I want to present a set of facts to the KZR Detective Squad. As usual thanks for any advice.

1. The PO did hit a deer while riding it at fairly low speed on a gravel road. He dropped it but aside from a dent on the fender and one on the tank and a bent foot peg it was rideable.

2. I rode it for 7-8 years and never had to panic stop it but grabbing a handful I never noticed the bars shaking.

3. I mounted non-stock dual rotors and swapped the forks left to right so I could mount the calipers behind the forks.

4. Putting it back together after swapping the forks I needed a buddy to help slide the fork tubes back into the triple tree. Not a pry bar or anything just a decent amount of muscle to slide the second one up through the top clamp.

5. Now when I grab a good handful (hard braking, not locking it up) the bars shake quite a bit. Not a tank slapper but something I don't have the arm strength to dampen by any means.

Yes, a dozen variables changed and I'm bumfuzzled as to where to even begin

Are the forks bent, sounds like it.
Steve

When I got the forks rebuilt the shop noted that they were bent and that they straightened them. Guess I should have put that important thing in my list of facts. Triple tree bent?

bent forks might make the bike wobble just riding but the fact it is pronounced under braking still makes me think it is a warped rotor

I would never straighten forks. :dry: Trees might be bent. How about your steering head bearings?
Steve

I didn't know you could straighten forks? Who would think of this?

You mentioned earlier about issues with bleeding the calipers due to bleed nipples being inverted now... Were you able to resolve this? Did you get a successful bleed on both sides?
Is it possible that one (presumably the "new" one) of the front calipers is semi-seized and perhaps not putting equal force on the rotor.
I have to agree with the good Doctor here if it's only happening during braking....
Is the front fender acting as a brace for the forks?

I experienced front end speed wobbles while racing an RD350 across the 401 eastbound late at night. :ohmy:
Now that's a super pucker moment.
Think I sucked part of my saddle in and compressed my knees into the tank about 1/2" on both sides.
Ease off, Don't panic. Smooth. Get under 80. Breath. :whistle:

Straightening forks is not uncommon and works fine as long as they are not too bent. Most old-school shops will now how to do it. dealers typically wont do it because the want to sell you new parts.

framestraightsystem.com/Motorcycle%20Fork%20%20Repair.htm

Thanks for all your responses, you guys are the best.

At this point though I'm pretty sure I'm past the limit of my tools and skills so I'm going to take it to the pros and have them go overt the whole front end from axle to handlebars and everything in between. The local dealership (Ottawa Goodtime Centre) has a good service department and instead of getting all hinky about working on a 40 year old bike they love it. The parts manager is a bit of a local legend when it comes to Kawasaki parts, a regular walking Google he is.

ETA: Also, Bruce, the parts manager has one of the new H2's, jeebus.

wrenchmonkey wrote:
I experienced front end speed wobbles while racing an RD350 across the 401 eastbound late at night.

Brave or crazy? I vote both

Hey! I resemble that remark! :laugh:

In truth, I think it was more ignorance than anything. I was barely 20-something at the time. Had no idea that the RD in RD350 was an acronym for "Ridiculously Damn (fast)". That night we were just cruising home from the night shift at work together. He was heading further east toward Pickering and I dropped out in West Hill, old Kingston Road. None too soon either. I'm frankly amazed I lived through my twenties.
But, I did learn what "speed wobble" means. Never want to learn that again! :blink: