Wobbly forks at speed

[MrMike]

I have a 90 CBr250rr and cruising up to 120kph is fine not a problem but if i continue to accellerate the front wheel begins to wobble by about 150kph i have to back of cos its vibrating pretty bad.
At first i thought could be shagged head stem bearings but had a look and they appear to be fine, not loose and have nice smooth movement.
Then today i noticed the wobble is actually in the bottom of the forks, the dust seals are pretty knackered and have cracked up a lil bit so they need to be replaced and u can see and feel movement around this area.

Is it fixable? New seals and change oil? or is there more likely to be more terminal damage in there and i'm better of just tryin to find some new forks?

cheers mike

[Nero Diablo]

Tyre preasure, tyre wear front wheel bearings and suspension setup can all affect this/cause it. Check the simple stuff first. The wobble is movement between the bottom case and the slider of the for it it just eminates from the bottom of the forks? The bushes and the like could be flogged out too all rebuildable cost a few dollars though.

[Hostilemonk]

19 year old bike - depending how and where it used could be fork staunchion wear. Take front wheel out, grap bottom of one fork and also high up on fork leg and see if any movement, do same to other fork - if there is movement then forks need a bit of work - if no movement (and it only needs to be slight - could use a dial gauge if got one). if no movement then check the things Nero said. - you may want to check forks for being straight also.

[MrMike]

cheers for replies.
I checked tyre pressure this avo and its 19psi front and rear so will have to pump them up a bit lol.

probably gonna pull front end apart next weekend and do brakes, seals and bearings. Hopefully that solves it.

Slightly off topic whats the best way to stand a bike up so front end can be pulled apart, i assume the fairings have to come off. Can i rest it on a milkcrate on the headers?

[Hostilemonk]

You can not advisable though - some use a strap over a beam in a garage, the best is a front headstand that the racers use for pit work - but they can cost - depending on frame another is a bar behind headstock and on stands at the side - another is auto stands under the frame rails - have a look at your frame and see which gives you the most stable platform - maybe some on here have the sdame bike and used a particular method.

[Semi]

I pulled the exhaust off and put a jack under the sump.

[M|ke]

Maybe the allignment of the front wheel is off? Not sure..

[Semi]

How do you align a front wheel?

[Nath]

Its done by tightening the pinch bolts in the correct sequence.

[Speed Demon]

Before you go for the big stuff
try a front wheel balance

[Falcore]

low tyre pressure wouldn't have helped at all

[druu]

I pulled the exhaust off and put a jack under the sump.

Did some work recently on a mates CBR and we used a scissor jack with a small piece of wood on the filter housing without removing the exhaust or fairings.

[Semi]

That'd do. Actually, I dont think you have to remove the exhaust to jack up by the sump either.

[fincl]

I have a 90 CBr250rr and cruising up to 120kph is fine not a problem but if i continue to accellerate the front wheel begins to wobble by about 150kph i have to back of cos its vibrating pretty bad.mike

Where did you get it above 110 ;-p

[Tannhauser]

Where did you get it above 110 ;-p

International waters

[MrMike]

private rd of course my old man is the king of australia and has a heap of dead straight and flat roads at my disposal. Also have an international standard elephant jumping stadium, biggest one in southern hemisphere.

Back on topic, pumped the tyres up from 19psi and its made a huge diffrence to the bike overall not suprising really and feel a bit stupid for not thinkin of that at first. There is still a slight vibration but i'm hoping fork oil change will reduce that.