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Discussion Starter #1
So I was riding on I-94 a couple days ago and traffic was running a little fast between 75-80 mph. So I was cruising along at about 78 when I came up to a semi. I personally don't like semis when I'm on the bike because of the limited visibility and 16 tires ready to blow. But anyways, as I'm passing this semi at about 85 mph I could feel my bike (2005 Honda CBR 600 f4i) beginning to shake and feel like every 5 ft there is a little divot in the road causing me to bounce. I checked the tires and they are at correct psi (32 front 36 back), so do other's bikes also have this situation occur when you're going 80+ mph or do I have to work with my suspension?
 

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Never happens to me and I go way faster than 80 mph :) Chain adjusted properly? Rear wheel alignment correct? What have you done recently to the bike, did the problem just start? More info is needed....
 

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Discussion Starter #3
1. I do need to check chain because I can assume the previous owner didn't.
2. Rear wheel should be aligned it's only been replaced once and that was by a mechanic.
3. Noticed it the first time I hit 90 on a county road haha. Which was the second day after I bought it!
 

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Every time I pass a semi on the highway the draft and turbulance it creats in the air causes me to kinda shake. its because the semi is displacing a large amount of air going down the highway at 65. the wind is being pushed around the front and outward twards your lane. thats what I think describes it, now i am no scientist though lol
 

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Discussion Starter #6
It's not just when I pass semis but when I pass any car or when I'm on the freeway and going 80+ mph. Idk I'm going to check it out and see if it's the chain otherwise I may have to take a day and fix her up.
 

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Adjust speed slowly. Transition from 75-76-78-79-80-ect. See if it is at an exact speed that it occurs. Sounds like a balance issue, if not perhaps Steering Damper, or front forks out of adjustment. Ive seen this before, but usually with peps doing wheelies. causes play in the steering neck bearings, and it will shimmy, and bounce. Good luck with it.
 

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Discussion Starter #8
At exactly 80 mph it begins to shake. Then at 79 it's smooth as glass. So I don't know what's really wrong... I'm gonna work on the chain soon here but otherwise I may have to take her in and get checked out :( unless someone possibly has suggestions. I know my way around bikes with tools but I don't want to try something that'll screw her up for good when I can pay a professional and be riding again next week.
 

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Discussion Starter #10
No I have not, but I'm not exactly a experienced motor head. I can do the basic maintenance but otherwise I just know how to check fork seals and stuff like that. If someone could possibly describe what actions I should take to check the alignment or bearings or whatever may be the issue that'd be great. I have relatives who are mechanics, but none are very close by. But thanks for all the help so far guys. I've also noticed that it bounces at about 40 mph also when I'm at low rpm in 5th/6th gear.
 

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Discussion Starter #11
Alright, so my issue hasn't been resolved yet, in fact it has become worse. This year when I took it out for the first time I realized that at 77 mph the front tire begins to shake. It shakes so hard that the windshield slightly rattles. I think it may be linked to unclean brakes that are grabbing the disc, because after riding if I feel the braking discs they are hot even though I didn't use them. Has this happened to anyone else before? Any other suggestions?
 

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The brake disks heating up are normal. The pads stay in contact with the rotors slightly even when the brakes aren't being used.

I still think the steering head bearings are the most likely suspect.

If the brake rotor is warped, it could cause some shaking. You can check it by lifting the front end and spinning the wheel. Check for the wheel itself and/or the rotor being out of true.

You can check to see if there is any play in the steering head at the same time. Any sloppiness in the bearings is a bad sign. Do a fall-off test to be sure the bearing tightness is withing spec according to the manual.

The wheel bearings can be inspected at the same time as well.

The only other thing I can think of is the tire being out of balance. If it threw the wheel weight, that would be a clue as to if it's the problem.

You can build a rig to get a fairly accurate gauge of the wheel balance, but it won't come close to the accuracy that a shop with a proper wheel balancer can get.
 

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Could be a number of things, either individually or even in concert
Worn front tire
Out of balance front tire
Worn/loose steering stem bearings
One or both forks low on oil (due to leaking seals) causing improper damping, especially if it's one and not the other
Wheel alignment
Play in the rear swingarm

Start with the easy stuff and work your way up
 

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well since he hasnt posted since June, I think its safe to assume one of two things happened. hopefully he got it fixed and hasnt had time to respond as to the problem...
 

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Do you have a steering damper? My 04 ZX-10R would have front end vibrations at certian speeds. After I installed one never happened again.
 
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