top speed

[KILLERCUDA_83]

Im thinking about buying a xr650r for dirtroad racing. When we race down our country dirtroads we go as fast as possible. I need something that does over 110mph how fast can u get one of these bikes to go and what are they geared at int he tranny for top speed possible? I understand u can go up on the front sprocket or down on the back sprocket to get top end but i dont wnat o have to go down to far. Is 125mph capable out of these bikes and im serious I think this one banshee will do 120 hes got it geared high and its really fast so i want to be able to do 125 so i can stay way infront of him. Oh i know this all sounds insane but well im a little wild and crazy and love going fast so i guess im alittle insane myself. and please no negative replies if u dont have anything positive to say then jsut dont say it all

[crfdude86]

go for the ktm 525mxc!!!

[irondude]

Positive-you cant go 125 on a 650R in the dirt.

[qadsan]

Positive-you cant go 125 on a 650R in the dirt.

Mike, do you remeber that Dirk Bike or Dirt Rider article a few years back where they had a top speed shootout among various bikes (KTM, Yamaha, CRF, etc) and the 650r beat out all the other bikes tested? Do you remember what that top speed was?

I thought the 650r's top speed was in excess of 120+ MPH under optimal conditions across the dry lake bed they were testing on while using the HRC cam with proper gearing and various bike parts removed while staying tucked down with the wind at their back etc, but I don't have that article anymore. Does anybody here have it for reference?

[huntmaster]

go for the ktm 525mxc!!!

But he wants to go FAST!

[qadsan]

OK, I found a post by XRANDY a ways back where he quoted the following...

In the March 2002 Dirt Bike Magazine, they did a test on the absolute fastest dirt bikes on the planet. They where the Honda XR650R, KTM 540 EXC, Kawasaki KX500, and the Husaberg 650.

All bikes were modified to produce the highest speeds possible. Mild porting, cams, pipes were used and the KTM was bored to a 540. The Husaberg was the most stock of the bikes.

They did top speed runs in two directions, and averaged the speeds. The results were:

Honda 111.4 MPH

KTM 109.1

Kawasaki 107.6

Husaberg 103.6

I don't remember the 650r having any porting work, but I recall the article talking about the 650r using the HRC cam, but not the high comp piston. They also used the PC' BatWing on this bike and said it made a difference at high speeds. I wish I still had my copy of the 2002 Dirt Bike Magazine so I could reference it and or scan it, but I loaned this and other issues to someone while they were recovering from surgery and they tossed a couple years worth of magazines I wanted to keep

KILLERCUDA_83, if you want to put some money into the engine (i.e. 680 kit, cam, porting, valves, exhaust, piston, coatings, carb, rod, etc), then you'll be much closer to your goal and will probably be able to exceed 125+ under the right circumstances.

[ImpalaR1]

You shouldn't get any negative comments for asking what u did. We all love power thats why we love the xr650r!! I'm sure with a few mod's u could get 120+ out of one, with it pulling hard all the way up.

[Mikie1]

On dirt it's a matter of traction. Wind resistance increases exponentially with speed. Even marginal inrcreases in speed create significantly higher drag. The engine would have to produce about 1.8 times the horsepower at 120mph than it takes to go 90 mph. Even if the engine had that much power to overcome the not-so-aerodynamic shape of the bike and rider, there isn't enough traction available to overcome the wind drag (SEVERAL hundred pounds). This is why the Pig destroys knobbies on the street- they are trying to spin, generating a ton of heat, at which point the knobs eventually bend over and pull off the carcass. On dirt they just spin.

I've seen 105 mph on my GPS when my bike was bouncing off the rev limiter, but doing the math, based on my gearing and an 8,200 rpm rev limit, I should have been going about 117. I don't think you'll be able to get 120 on dirt without some serious aerodynamic work and/or other means to produce more traction.

[J_Daniels]

On dirt it's a matter of traction. Wind resistance increases exponentially with speed. Even marginal inrcreases in speed create significantly higher drag. The engine would have to produce about 1.8 times the horsepower at 120mph than it takes to go 90 mph. Even if the engine had that much power to overcome the not-so-aerodynamic shape of the bike and rider, there isn't enough traction available to overcome the wind drag (SEVERAL hundred pounds). This is why the Pig destroys knobbies on the street- they are trying to spin, generating a ton of heat, at which point the knobs eventually bend over and pull off the carcass. On dirt they just spin.

I've seen 105 mph on my GPS when my bike was bouncing off the rev limiter, but doing the math, based on my gearing and an 8,200 rpm rev limit, I should have been going about 117. I don't think you'll be able to get 120 on dirt without some serious aerodynamic work and/or other means to produce more traction.

Regardless, he's gonna smoke the competition, they have the exact same limitations. My geared up and uncorked BRP runs with piped CR and KX 500 two-strokes in the dunes, no problem. They can gather me up after a while, but the holeshot just kills 'em. GPS'ed at 104 mph in the sand; that's fast, no way around it!

[KILLERCUDA_83]

Well my yz250f will do 86 and gets plenty of traction at htat speed and it wants to go faster jsut gears wont allow it. I will find a way to get traction if i have to rig up a spoiler of some sort to create drag pressure to push the back wheel down to get better traction i will find a way but we also do alot of drag racing in sand so i will be using it for that to.

[Supplicate]

an uncorked, otherwise stock, BRP has a recorded 105mph (± 5 mph thereabouts) sustained speed at 7,500 feet.

The reason I know this is I am the one who was riding it at the time and have the tracking on the GPS unless its been reset. And no that wasn't going downhill with the wind at our backs, it was on a ride up an oilfield road that has many sweeping turns and up and down downs etc.

I'll have to track tomorrow if I go ride and see how fast I can have it on that same stretch of road.

[frankstr]

I hope you have a good medical plan.....

[KILLERCUDA_83]

OH no worries here i got full medical coverage so no matter howmuch the cost of fixing me up the doctor bill will be covered so if i wanted to i could go full speed and jump off a 100ft cliff and whatever it cost to pull my head out of my a$$ it will be covered even if im full of shi!!