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Magic 100mph

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So I've been doing a lot of high speed runs on my '12 DR650 (8000 miles) lately and notice I can't seem to hit 100mph. Bike is stock except for fmf q4 muffler. I haven't got a gps but am able to pull up to around 90mph before it goes into creeper mode. With a long enough straight It'll climb to 93mph at best with my head down and the wind on my side. From what I hear the stock speedometer reads fast so I must be going slower again. Just got me wondering if there's something wrong with my DR or if the bike needs to be fully uncorked to reach these kinds of speeds.

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About the same speed for my completely stock '12 DR650. Only 7200 miles, that winter thing gets in the way.  Upright I can hit 90 easy, laying down I got up to 98 before I backed off, but it took about two miles to get up to that speed.

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You can always drop the rear sprocket some teeth. My DRZ400 is dropped 6 in the rear to a 39 tooth and I can cruise 90 pretty easy. You can always wait to get a new sprocket when the time comes, or leave it as is of course.

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Mine is an uncorked 09 with a pumper carb and full FMF system and it won't do 100 instrumental with the stock gears.  The most I've been able to do is about 96-98 on speedo.  Which BTW is about 7% off according to my GPS.  So its really more like 90.

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thanks t30 I thought my '12 DR ran pretty well in stock trim despite all the rumors I hear from mates claiming they regularly hit 100+ miles an hour..

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Stock bike with 14t CS sprocket at 5400 feet - 94 indicated on the speedo, 87 on the GPS. The engine was no where near redline so its unlikely it would go any faster up there with a larger sprocket. However, I would expect a little more in the more dense air at lower altitudes.

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I'd love to know what the dr790 with all bells and whistles would do in a top speed run. I'm thinking 120mph wouldn't be out of the question.

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I'd love to know what the dr790 with all bells and whistles would do in a top speed run. I'm thinking 120mph wouldn't be out of the question.

Depends a lot on where the engine makes its power. In stock form, the DR650 is a "thumper" achieving maximum power well below redline. Changing that would likely require more radical valve timing, improved breathing and a sacrifice of low end performance. If that's your style of riding, you'd be far better off starting with a bike/engine designed for top end performance.

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Just to interject a bit of science into this discussion. Many people report their DR650 will achieve 90mph in stock form. And, before all the protests start, lets remember that the US version DR650 speedo is around 7mph fast so a real 90 would show 97 or so on the speedo. Okay so, let's assume it's actually making the advertised 37 hp at that speed. All else being equal, to increase the speed from 90 to 120 mph would require ~2.35 times more hp (http://drive55.org/content/view/60/6/) so that means the motor would have to be pumping out around 87hp at 120. For a 790cc engine that would be 110 hp/liter. Seems to me that would be a stretch for a single cylinder, non-supercharged, air cooled engine. :cool:

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Yeah I wouldn't expect to pull 87 hp out of a single cylinder, non super charged, air cooled engine either. If I'd done my research and the math I'd likely have come to the same conclusion. I was making and uneducated guess thinking it'd spur some interest.

Edited by Eazy-E

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100 MPH indicated on the stock speedometer is actually closer to 95 MPH anyway.

Tech25

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Intersting? My drz (when bone stock) showed 102 indicated or roughly 95 actual while making around 32 horsepower. My dr350 with calibrated vapor has shown 85 actual. I would think a 650 should have no issues hitting 100. I know my drz can there easily with a quick sprocket swap (making upper 40's horsepower now though).

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So I've been doing a lot of high speed runs on my '12 DR650 (8000 miles) lately and notice I can't seem to hit 100mph. Bike is stock except for fmf q4 muffler. I haven't got a gps but am able to pull up to around 90mph before it goes into creeper mode. With a long enough straight It'll climb to 93mph at best with my head down and the wind on my side. From what I hear the stock speedometer reads fast so I must be going slower again. Just got me wondering if there's something wrong with my DR or if the bike needs to be fully uncorked to reach these kinds of speeds.

 

Yup. You need to uncork it. With a Procycle carb kit, a UNI filter in a cut airbox, and FMF muff, I hit 101MPH on the GPS. The speedo looked to be at about 106MPH when I glanced down...and was slowly passed by another guy on his jetted DR with a DG muff and a silly grin that I could sense through his helmet. This was on flat packed dirt, at around sea level, on a cool day, in a tuck. I'm around 200lb.

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