1999 CBR600F4
19k miles

Background Information
- When I purchased the bike in April of this year, the bike had 17.5k miles on it. When I would exceed 45mph the head bar would develop a shake. This "shake" would get increasingly bad up to 55mph where it seems to be the worse. Increasing speed above 55mph seems to have a less severe head bar shake but it is still there. Upon letting off the throttle and weight shifting forward, the shake increases in severity until the bike levels out. The severity of the shake also increases when I ease onto the front brakes. I'd like to assume the problem lies within the brakes. If you have ever driven a car with warped rotors, the shaking in the steering wheel is equivalent to that.

- When I purchased the bike the tires needed replacing and the front tire was cupped. I assumed this was the cause of the head bar shake and purchased Dunlop Q2's. I dismounted my wheels myself and took them to a shop and had them mounted and balanced. I mounted the wheels back onto the bike only to find that this was not a solution to the headshake.

- My brake pads are worn to about nothing and I have yet to replace them. I am ordering some EBC pads in the next few days.

- I have not attempted to lift the front wheel and test the head bearings due to my strong assumption the problem lies within the brakes. I will try and do this test sometime this week.

I am hoping to obtain some further advice and beliefs on the matter to help identify the true problem.

Thank you,
Samuel

 

Any chance the bike has a top box or panniers on it ? - some bikes are very sensitive to them.

Have you set the sag on the suspension for you ? - if either end is too soft or hard compared to the other it can cause shakes.

You have already mentioned the headset - that can cause shakes too.

 

Try the diagnostic test you have mentioned first then go from there. Its either worn/defective brake calipers/ pads, rotors, headstem, wheel bearings or axle. Check those first. Also look in a manual for the procedures.

 

Personally I don't think I would be riding it in that condition. I would definitely check the wheel bearings and the axles for excessive wear. the wheel locks up on you you're going to be replacing a heck of a lot more than brakes some bearings.

 

Update:
I replaced the brake pads. Shake is not as bad as before but is still there. The braking does not seem to cause the shake to increase as much as it did before, but it does feel like the rotor might be catching in a few spots.

Right side caliper brake pads were worn to the metal. Looks like uneven wear on the rotor. There appears to be a lip on the edge of the rotor in some spots and some spots are smooth. Pads installed easy with no problems.

Left side caliper brake pads had just a little pad left. No noticeable wear on rotor. When I was trying
to install the new brake pads on the left side, the caliper pistons would not stay pressed back. They would slowly be pushed out to about 1/4 inch. I had the cap off the brake fluid reservoir.

I still have not done the head bar test.

 

Update: turns out the front rim is bent. I'm confused. How would the guy that put tires on bike be able to balance them? Or atleast say he balanced them? Is there any companies I can get a new wheel from? Aside from Honda for $600

 

I'm a tad curious how exactly did you find out the rim was bent after all this time? Also you should def tell the shop that mounted the tire.

 

You can normally find good deals on rims on eBay. That sucks, didi you take the rim to a cycle gear or a shop like that, or an actual mechanic?

 

I'm confused myself.

The guy that mounted the tires for me runs a Goldwing shop out of his house. He specializes in Goldwing repairs and maintenance. My dad gets tires for his Goldwing with this guy and recommended him. So I had him mount and balance the tires for me. I experienced the same "shake" after getting the new tires and called and asked the guy if he balanced the tires correctly. He assured me his balancer is top of the line and the tires were balanced. If the rim is bent then how can he claim to have balanced them?

I began throwing parts at the bike. I purchased rotors because I knew those were warped and did brakes all around.

I bought some All-***** front bearings. I took the front wheel off and took it to the local Honda dealer and asked them to check and correct the balance on the front wheel and asked if they could throw the bearings in. That is when the Honda tech learned the front wheel was bent. My confusion with this is that the the Honda dealer had the bike in April to rebuild the clutch. They also did a safety inspection and this issue was not noted anywhere.

I feel like I've been let down by a few different service providers :/

 

I'm afraid of getting a rim that's not true off ebay.