650r steering wobble


9 replies to this topic
  • skyhighdaz

Posted August 06, 2007 - 03:55 AM

#1

OK, in SM trim and at med to high speeds, I get a little instability issue with the BRP. I know, I know, this ain't a sport bike. But the 15ish miles of straight and level roads to get to the good stuff needs to be a little more palitable. Just a little touch either way at speed tries to send this thing off in the briar patch.
Would a fork brace fix it ($80) or do I (non race guy) need a stabilizer($300+)

Thanks experts!
Mark
Central CA

  • porterdog

Posted August 06, 2007 - 05:01 AM

#2

The stabilizer would help for sure, but before dropping that much coin I'd make sure that a) the sag was set correctly for my weight and then B) experiment with the height of the forks in the triple clamps. More fork above the top clamp quickens the geometry and makes the bike twitchier; less above does the opposite. I'm currently at 10mm (just under a half-inch) of exposed fork tube above the top clamp and thinking of going to 20.

Also, on my XR4 I find that while the geometry is good at lower speeds (30-50) it'll get a little wobbly going faster. Shifting my butt back on the seat has the same affect lowering the forks in the clamp and settles it down a bit.

hth,
Robert

  • Kyron

Posted August 06, 2007 - 05:55 AM

#3

what size tires do you have?

X2 about droping the forks in the clamps.

  • Suikerland

Posted August 06, 2007 - 08:13 AM

#4

Could be a combination of factors. Try different tire pressures as well.

  • hill5150

Posted August 06, 2007 - 10:45 AM

#5

SRC Fork brace, or similar, Scotts stabilizer....... and tire pressure, will be a factor as well............The stabilizer is pricy but worth every penny..................

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  • skyhighdaz

Posted August 07, 2007 - 03:54 PM

#6

17" Exel with about 24psi in front and 26 rear.

  • pwrpapa

Posted August 07, 2007 - 08:11 PM

#7

Have you checked the triple tree bearings? They may need to be greased or replaced.

  • eastreich

Posted August 07, 2007 - 08:18 PM

#8

If you are running the stock forks (and I assume you are), you most definitely need a fork brace. With the wider front tire and the absolute traction of asphalt, you are putting enough of a load on the forks that the flex is causing the wobble.

I don't supermoto mine, but I race it pretty hard. It was a huge improvement when I put a SRC brace on my 650R. If I were you I would get the SuperBrace. Just because I think it has a better "look" for a Supermoto IMO. In the end, I have gone with inverted forks because even with the brace, I was leaving black marks on my headpipe from the forks bending back and allowing the tire to hit the pipe going through whoops and landing off of jumps.


A Scott's will solve the problem also, but it is a band aid for the real issue of fork flex in your situation.

  • Billahjack

Posted August 08, 2007 - 06:42 AM

#9

What tires are you running? I have noticed huge performance/stability differences between tires. Also, what is the condition of your front tire? New/used/abused/no more tread blocks/Heavily feathered tread blocks?

I've taken Dunlop D606, D952 & Michelin S-12 front tires just past 100 MPH on the street. The 606 was the best and the S-12 was the worst, but off road it was opposite.

I have found that the dirt bikes only offer a little amount of stability. You need to keep at least 1 hand on the bars over 50 or 60. From what I hear, stabilizers go the extra mile if you still don't feel like its right.

On my street bikes, they would start to wobble when the front tire was at the end of its tread life.

  • skyhighdaz

Posted August 10, 2007 - 03:45 PM

#10

Right now they're slicks, ah, not supposed to be but just got the 17" excels and came with worn out Maxxis rear, 50% tread on front. But they will soon be Dunlop 208 GPs on the 17's.





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