I've been going through the big, big list of things that is affecting my laptimes at Anglesey, and the biggest cause for my concern at the moment is the amount of front end chatter I'm getting coming through 'church' (the fastest corner in the track) mainly once I'm coming through the apex but on my fastest lap yesterday it started a lot sooner. Its quite severe, and seems to cause the front of the bike to start drifting towards the outside. I can only guess if it got any worse I'd be on my arse..

It can be lessened by getting on the power earlier, but that also widens the turn which is less than ideal.

The front preload is on max now, to try and counteract it but to no avail.

Any ideas? Rebound damping too soft maybe..?
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More **** two strokes than you can shake a **** stick at.

This may seem strange but when i raced and i got front end chatter you could sometimes cure it by adjusting the rear. I believe it is a case that by adjusting the rear ride height/pre load it alters the way the front reacts due to weight distribution. Might be worth a phone call to a suspension expert like Maxton.

I expect someone will shoot me down in flames but it seemd to work for me on both my KR1S and TZ250!
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MC21 300
Aprilia RS250 track bike

Have you had the suspension rebuilt, or is it the same stuff fitted 16+ years ago? If it is, you really really ought to spend the cash and have it done.

Assuming it is, then maxing the pre-load is surely going to make the chatter worse, as the suspension is so hard it can't follow the track surface properly.

I'd have thought softening the pre-load and upping the damping would be the right way to go.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Chatter is always suspension basically too hard (as T3 says you can alter that by changing rear ride height and you've found you can do it with the throttle too)...that's what chatter is, the bike is over so far neither the suspension nor the flex in the chassis, wheels or tyres can dampen the vibrations from the road surface.

Church is ultra fast, flat out (apparently) for the fast fast fast 250 boys once you've got the bike turned, Alan Armour ground his exhaust out there, lifted the rear and crashed...think about that, so take a deep breath and do it!
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Please do not PM me technical questions, if you can't find it on the Forum start a thread

From the HRC manual

Chattering : Raise or lower tyre air pressure. Review tyre selection
: Resonance under spring due to inadequate damping force
: Shift resonance point by either increasing or decreasing initial load

We also found using a heavier front wheel spindle often cures things too, comes back to moving the resonance point I guess.
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If I have to take the carbs off once more...

Just my pence worth usualy crap.

in superetards the bikes can suffer lots of chatter and after trying dialling it out with suspension the best things that worked were, 16.5' front lower tire pressure and then off set triple clamps -4mm and last better springs, maybe old ones were worn and tired.

The tyre profile has a larger side wall to soak it up (in theory) and to all purposes helped.

What size tires are you using? allso when was your suspension looked at?

Last thing for me would be chassis set up inc all your ride heights and preloads especially the back, I learnt more from Mr Matt about suspension than i could ever soak in. He was good enough to help me years ago and it helped me understand that bike balance is important.
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Farting is funny

Well thanks for the replies all.

Yes the front end does need sorting, I've fitted racetech uprated springs, upped the oil to 15w and a little more quantity so it damps quite nicely. I was considering welding the holes up and re-drilling them slightly smaller until I find a nice enough compromise. Or a set of emulators may come my way..

The shock is off a cbr929, works well but is a little on the soft side. Everything is pretty much maxxed to get it to perform. I'm looking into a replacement.

I'm using Dunlop D209GP's. 110/70/17F and 150/60/17R.

Fontyy, yeah church does seem to be a corner for the brave. I think get that one right and you can pretty much pass most coming up the hill. See how it goes but the dirt does look very inviting on the outside
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More **** two strokes than you can shake a **** stick at.

Chattering is a real bugger. It's a bike racer's nemesis!

Most of the answers given already are right, but if it was as simple as that then you wouldn't hear MotoGP riders complaining of it.

I could reduce front end chatter on my CR250 retard by changing the spokey dokey wheel to a (heavier) NSR wheel. Similar thing to what Steve says. This heavier hoop decreased the speed that the front wheel moved through the suspension stroke, so chatter wasn't as violent.

In your case I'd increase the rebound damping on the front. Sounds as if it's starting to lose traction into the turn, and as it does it fires the front wheel away because of lack of damping, than grips then slips etc, and so the suspension loses control.

How does it feel on the anchors? A bit squidgy? In the case of the NSR, the stock forks ain't much cop as they're built for a 55kg Jap to cruise Ueno at 3am making a racket.

Matt, it feels a bit soft on the front mate. But then std forks with modified internals are always going to do that I guess..

I wonder if running a stock (instead of magtek) wheel will do anything to stop it?
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More **** two strokes than you can shake a **** stick at.

A stock wheel might help. Give it a try.

The difference between a heavier wheel and a heavier axle (as Stephen mentions) is that you'll get the added inertia of a heaver rim, which will affect direction change more than a heavier axle.

No reason why stock forks with modified internals should be bad. Just look at a RWU RS fork. Nothing much wrong with them and very similar to an NSR fork.