Posts
15
Joined
6/5/2009
Location
Wollongong, AU
Edited Date/Time
1/23/2012 8:00am
Hey guys., just wanting some input on a slight problem,
Here's the story, I recently changed the springs in my Yz250 to 0.50kg/mm front and a 5.5kg/mm rear to suit my weight, the change is unbelievable to say the least, the bike steers, tracks and jumps better than I every expected.
All clickers are in the stock position according to the manual.
I have no complaint what-so-ever with the rear, it's perfect in my opinion.
But the front works awesome at slower speeds and over the rough stuff but once I get onto highspeed straights, 3rd wide open, I get alot of headshake, no matter how smooth or rough the track is.
I know of 2 options I can go with, one being re-valve, which I think would be best, the other being to fit my MSC steering stabilizer, which I'm not so keen on due to the fact that I then have no bar pad because they only make the mount to go on the top of the bars, and I don't think my chest or face would like that too much.
So, does anyone have any other ideas, or do they recomend go with what I've said?
Thanks in advance for any help..
Here's the story, I recently changed the springs in my Yz250 to 0.50kg/mm front and a 5.5kg/mm rear to suit my weight, the change is unbelievable to say the least, the bike steers, tracks and jumps better than I every expected.
All clickers are in the stock position according to the manual.
I have no complaint what-so-ever with the rear, it's perfect in my opinion.
But the front works awesome at slower speeds and over the rough stuff but once I get onto highspeed straights, 3rd wide open, I get alot of headshake, no matter how smooth or rough the track is.
I know of 2 options I can go with, one being re-valve, which I think would be best, the other being to fit my MSC steering stabilizer, which I'm not so keen on due to the fact that I then have no bar pad because they only make the mount to go on the top of the bars, and I don't think my chest or face would like that too much.
So, does anyone have any other ideas, or do they recomend go with what I've said?
Thanks in advance for any help..
Did you add rebound to the rear shock to compensate for the additional stored energy? Try going in 4-5 clicks.
When you installed .50kg fork springs and only a 5.5kg rear you changed the balance of the bike decreasing trail. Decreasing trail makes the bike easier to turn, but at the expense of headshake. If you are on a budget, try raising your sag, if it's at 100, try 90. This will increase trail, and/or put more weight on the fork springs while riding.
You are either going to need softer fork springs or a stiffer shock spring. If your shock's sag numbers are correct (30mm static, 100 rider), then your fork springs are just way too stiff. When forks have head shake while accelerating, it is caused by a lack of traction, this is caused by deflection, (too much spring, or damping) or oscillation (lack of rebound damping control during small movements)
Also, check your tire pressure and steering stem bearings. You should tighten your steering stem so that it can't fall from side to side on it's own. It should require just the smallest amount of pressure to move but it will stop once you stop applying pressure. If it keeps going and "falls" until it hits the steering stop tighten up the steering stem collar.
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Those springs are quite a bit stiffer than stock so you'll need to crank in 2-4 clicks more rebound, front and back, to control them. Stock compression settings should be close. Run 4" of sag.
I'll give your suggestion a go next time on on it.
Thanks.
And BIGHEAD1, I got those rates off the RaceTech calculator and then double checked it with a suspension tuner.
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