Posted by Mike Corey on July 27, 2009, 6:22 pm
Kind of on topic, it's a dual sport bike.
On my way home from work today on my DR650. On I80, in the left lane,
going about 70, planing to pass a semi truck. I look into my mirrors and
see a red van coming up fast. He pulls into the right lane and starts to
pass me. I could tell he had intentions of passing on the right, diving
back into the left lane and pass the semi before I got there.
Personally, people that do that really "T" me off. So I hammered the
650. When I hit the air wash from the semi trailer the bike went into a
high speed wobble, or what some people call a tank slapper, at 90 MPH!
Luckily I didn't panic, and just eased off the throttle slowly, and when
it got back to 70 MPH the wobble quit. I looked over at the guy in the
red van, flipped him the bird, and let him pass me on the right.
Never, NEVER will I ever do that again.
My question is, what caused this? It's never happened before. The front
tire pressure was 20 PSI, the manual says 22. So I doubt it was that, or
was it? Could it just have been one of those things? I hit the jet wash
from the trailer just right?
Posted by XR650L_Dave on July 27, 2009, 7:01 pm
On Jul 27, 6:22 pm, AWR7MM...@webtv.net (Mike Corey) wrote:
> Kind of on topic, it's a dual sport bike.
> On my way home from work today on my DR650. On I80, in the left lane,
> going about 70, planing to pass a semi truck. I look into my mirrors and
> see a red van coming up fast. He pulls into the right lane and starts to
> pass me. I could tell he had intentions of passing on the right, diving
> back into the left lane and pass the semi before I got there.
> Personally, people that do that really "T" me off. So I hammered the
> 650. When I hit the air wash from the semi trailer the bike went into a
> high speed wobble, or what some people call a tank slapper, at 90 MPH!
> Luckily I didn't panic, and just eased off the throttle slowly, and when
> it got back to 70 MPH the wobble quit. I looked over at the guy in the
> red van, flipped him the bird, and let him pass me on the right.
> Never, NEVER will I ever do that again.
> My question is, what caused this? It's never happened before. The front
> tire pressure was 20 PSI, the manual says 22. So I doubt it was that, or
> was it? Could it just have been one of those things? I hit the jet wash
> from the trailer just right?
the XR650L has a tendency to do this, generally thought to be because:
- really light front end
- huge floppy front fender
- tall bike
- flexi forks
- fairly steep rake and short trail
On the XRL it's one of those cases where stiffening up can prevent it,
as long as you realize you cannot allow motion from the bars to feed
into the bike.
I've had my XRL up to about 100 (indicated, so probably 90) and have
felt the front get light, but have never had it weave or shake
although it felt like it'd like to.
Dave
Posted by sturd on July 27, 2009, 8:59 pm
Mike Corey reports:
> When I hit the air wash from the semi trailer the bike went into a
> high speed wobble, or what some people call a tank slapper, at 90 MPH!
Check the steering head bearings. And 20 is a little low for
90 mph.
Small chance on either of those being the cause but I'd
check.
Go fast. Take chances.
Mike S.
Posted by scrape on July 27, 2009, 9:31 pm
On Mon, 27 Jul 2009 17:59:00 -0700 (PDT), sturd
>Go fast. Take chances.
I think he did.
Posted by dsc-ky on July 27, 2009, 10:44 pm
On Jul 27, 6:22 pm, AWR7MM...@webtv.net (Mike Corey) wrote:
> Kind of on topic, it's a dual sport bike.
> On my way home from work today on my DR650. On I80, in the left lane,
> going about 70, planing to pass a semi truck. I look into my mirrors and
> see a red van coming up fast. He pulls into the right lane and starts to
> pass me. I could tell he had intentions of passing on the right, diving
> back into the left lane and pass the semi before I got there.
> Personally, people that do that really "T" me off. So I hammered the
> 650. When I hit the air wash from the semi trailer the bike went into a
> high speed wobble, or what some people call a tank slapper, at 90 MPH!
> Luckily I didn't panic, and just eased off the throttle slowly, and when
> it got back to 70 MPH the wobble quit. I looked over at the guy in the
> red van, flipped him the bird, and let him pass me on the right.
> Never, NEVER will I ever do that again.
> My question is, what caused this? It's never happened before. The front
> tire pressure was 20 PSI, the manual says 22. So I doubt it was that, or
> was it? Could it just have been one of those things? I hit the jet wash
> from the trailer just right?
Dry dropping the front end a bit... raise the forks in the clamps and/
or raising the rear.
You can always add a stabilizer.
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> On my way home from work today on my DR650. On I80, in the left lane,
> going about 70, planing to pass a semi truck. I look into my mirrors and
> see a red van coming up fast. He pulls into the right lane and starts to
> pass me. I could tell he had intentions of passing on the right, diving
> back into the left lane and pass the semi before I got there.
> Personally, people that do that really "T" me off. So I hammered the
> 650. When I hit the air wash from the semi trailer the bike went into a
> high speed wobble, or what some people call a tank slapper, at 90 MPH!
> Luckily I didn't panic, and just eased off the throttle slowly, and when
> it got back to 70 MPH the wobble quit. I looked over at the guy in the
> red van, flipped him the bird, and let him pass me on the right.
> Never, NEVER will I ever do that again.
> My question is, what caused this? It's never happened before. The front
> tire pressure was 20 PSI, the manual says 22. So I doubt it was that, or
> was it? Could it just have been one of those things? I hit the jet wash
> from the trailer just right?