Topic: Front End vibration

[sepling]

I just got a 1977 CB400F and had the 20 year old tires replaced with new Avons (tubes in a tubeless tire).  I definitely have a "hop" or vibration feeling at about 40 miles an hour and above.  I've had the balance doublechecked (fine), the wheel trued (not to far out) and the head bearings checked (fine).  I've also drained and filled the forks with the proper amount of ATF as per the manual and I still have this problem.  Could it be the new tire?  It REALLY feels like the front end but could something in the back-end make it feel that way?  Could my springs be worn out or too heavy?  Are progressive springs available for these bikes?

Any help would be greatly appreciated.  I only rode it a few times before replacing the tires because they were downright scary so I didn't really have much to compare the new ride to.

Sean

[Gordon]

Jack up the front end and spin the wheel to see if there is any noticeable irregularity in the tire.

[Johnie]

Jack up the front end and spin the wheel to see if there is any noticeable irregularity in the tire.

While you have that tire up check those bearings too.

[tlbranth]

Are the tires seated properly? Like Gordon said, check each wheel/tire with it off the ground. Should be pretty easy to spot.

[sepling]

Thanks for the tips guys.  Reseated the tire and still "jumps".  Turns out about 1/4 of the rim is flattened.  It's over such a long distance that it's tough to see.  Gonna ride these tires out and deal with trying to fix it on the when the next set gets mounted since the tires need to be dismounted for a good trueing.