First ride of the spring, some questions:

[Keogan]

I redid the bike over the winter and today was the first day back, I have some issues:

(Bike is a 75' cb200)


after tuning the carbs I took off, and with the new shocks its a lot stiffer, and I have a larger front wheel from a 2.75 to a 3.00. As i got going i noticed a slight up and down of the front, and as I went on longer it got worse when going down a slight hill, to the point where the bouncing was nauseating. I'm no expert in vintage bikes but I hear that fork seals are often replaced.


Please help, ask questions, help me get my bike back to awesomeness.

 

[OneWheelDrive]

Sounds like your dampening oil is low, causing bounce. Draining the nasty fork oil and replacing it with automatic transmission fluid is a very easy operation. Check your manual with the amount to fill each fork with and ride happy.

 

[RedPlastic]

how old are your tires? wonder if they're flat spotted?

 

[VonYinzer]

Make sure the forks are properly filled, and not leaking. Also, use actual fork oil, n0t ATF.

 

[hurley209]

ditto, use some fork oil according to your weight and you should be fine.

 

[Canuck Plumber]

I dont think I have ever heard of anyone using atf in lieu of fork oil. I would think that would be detrimental to the seals, no?

 

[VonYinzer]

The old repair manuals actually suggest it. BUT, theres a reason its not in practice anymore.

 

[Keogan]

Ok, I'll check the fork oil. BOTH tires are brand new, so i don't think its that. I'll provide some updates when I ride again.

 

[crazypj]

First off, what sort of speed?
Next, who fitted the tyres?
Even if damping is non-existent you have to have something to cause the bounce in the first place, damping will eventually cancel out movement just through friction in forks, if it's getting worse something else is wrong
Seems more likely that there is a tyre iron inside tyre or it's severely out of balance for some other reason.
Are there any balance weights on wheel?
BTW, nothing wrong with ATF in forks, in fact, fully synthetic ATF can work better than 'real' fork oil in some cases
Do some research on suspension fluids and all sorts of interesting things come up (at least I find them interesting ;D )
Personally, I use 5w/40 full synthetic engine oil, works great for me 8)

 

[Titan performance]

I, like most, have ridden bikes with forks leaking, pitted, undamped and generally in crap order during my youth, but never experienced what you describe. My money is on an incorrectly fitted tyre.