Tank slap and wheel hop.

[Guest]

Over the winter, my front end was taken apart and put back together with pieces from both an 82 and an 83 to make a decent set of forks. The 83 tire and rim were the better of the two, so it was used. I am now getting the forks tryi to slap the tank at speeds between 35 and 55, but not lower or higher. There is no apparent slop on the stem bearings, and there is no bearing hang up as if they were bad. Also, the wheel is hopping at all speeds, but much more so at low speeds. I balanced the tire and it didn't change the hop at all.
Any ideas?

[Big T]

bad wheel bearings
Misalignment

Did you have the wheel dynamically balanced?

Bent rim?

[MunkyMastr]

I balanced it the fancy way...by spinning it on a rod and weighing opposite the side that's heavy. Not the most technical, but it has yet to fail me. I checked for a bent rim, but I didn't see any problems. I also forgot to mention the tire I put on had sat for a while, so it may have a flat spot. I'm going to order a new tire and go tubeless just to check that option.
Misalignment? I'm not sure what would be aligned? And bad wheel bearings could be a concern. I didn't notice any binding there, but I'll probably replace those too when I do the new tire.

[steve murdoch]

Different amount of air and or oil in the fork legs?
The front and rear wheels could be misaligned?

[SqDancerLynn1]

Did you re torque the stem bearing ?

[TheCafeKid]

First of all, what bike? What bikes did the donor parts come from? I know 82 and 83 bur what model? You could have spacer issues, offset issues, bearing issues, fork internal differences, did you reassemble the forks according to the manual and check for bind in them along the way? If one side is binding up you will get what you're describing as well. Did you replace both forks or just one from one model and one from the other?
Need more info

[MunkyMastr]

Sorry for the lack of info. One fork of each the 1982 and 1983 gs1100e was leaking from one area or another. We took the beat of each and made a complete set. Unless I am wrong, the 82 and 83 were basically identical?
I didn't do the seals, nor did I drain the fork oil from either. The air I didn't mess with because the wheel hop was bad enough to make me not want to pump up the forks and risk a seal blow out.
I'm new to the whole front end, never messed around with them much. Sorry for my lack of knowledge.

[allojohn]

After you've sorted all the other issues out, don't bother trying to balance your wheels - take a look at Dyna beads.

[5azzmonkey]

Sorry for the lack of info. One fork of each the 1982 and 1983 gs1100e was leaking from one area or another. We took the beat of each and made a complete set. Unless I am wrong, the 82 and 83 were basically identical?
I didn't do the seals, nor did I drain the fork oil from either. The air I didn't mess with because the wheel hop was bad enough to make me not want to pump up the forks and risk a seal blow out.
I'm new to the whole front end, never messed around with them much. Sorry for my lack of knowledge.

Even if the oil levels are both set correctly you may have two different weight oils in each fork. Drain them and fill them to the proper level and correct psi.

I'm pretty sure there is a tutorial in BikeCliffs site

http://members.dslextreme.com/users/bikecliff/

[MunkyMastr]

Big T for the win. Sorry to di up an old thread, but I got to working in it. I drained and filled the oils and put in matching springs, but it didn't change it. I took the wheel off to rebalance and I noticed it was WAY out of round. Threw my old 82 wheel back on and all my problems went away. Thanks for the input guys. I'm glad to have my baby back tip top.

[Big T]

I have my moments

Most of that wisdom comes from horrible experiences

[DannyMotor]

Was it the rim itself, or was the tire not seated correctly?

[MunkyMastr]

Twas the rim. We checked. It looked like it had been hit at one point.