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Original Article:
2013 BMW F800GT Review

Please discuss the Motorcycle.com article 2013 BMW F800GT Review in our Motorcycle Forums below. Use the reply button to let others know your comments or feedback on the article. Constructive criticism is always appreciated, along with your thoughts and personal opinions on the bikes and products we have tested.
 

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There's frequent criticism here about overweight, oversized ST bikes. This should answer that.

I'm sure its true, but saying that having both pistons rising and falling together reduces vibration seems counterintuitive. Wouldn't having more weight at each end if the stroke be more unbalanced and thus create more vibes? If anyone can explain that is appreciate it.
 

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BMW explains from BMW Motorrad International

There's frequent criticism here about overweight, oversized ST bikes. This should answer that.

I'm sure its true, but saying that having both pistons rising and falling together reduces vibration seems counterintuitive. Wouldn't having more weight at each end if the stroke be more unbalanced and thus create more vibes? If anyone can explain that is appreciate it.
Unavoidable on two cylinder engines, the first and second order inertial forces are neutralised by a balancing mechanism that is unique in our times. Instead of the conventional solution involving so called balancing or counterweight shafts, the oscillating inertial forces are eliminated by a system of articulated joints, positioned centrally on the crankshaft, comprising a predefined arrangement of counterweight masses. Arranged opposite to the crank pin, an eccentric on the crankshaft carries a so called balance rod. This rod is joined to a balance pivot. The kinematics are such that the balance rod moves up and down counter to the movements of the two piston rods. The movements over the relatively long swing arm gives rise to a relatively linear swinging motion for the rod end. The distribution of mass over the rod end and swing arm is such that the inertial forces generated by the swinging motion counteract the inertial forces generated by the crankshaft (piston and rod section) at all positions. This virtually eliminates the first and second order inertial forces, and the engine runs with low vibration levels. One other major advantage of this elegant design is its low noise levels because there are no gears or chains with their characteristic drive sounds.

BMW Motorrad International
 

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^ What he said.

I2 engines rock side to side rather than fore and aft.

That's why they do the cylinders at the same time.

Triumph does a 270 crank on some models to give it more potato potato or whatever the hell produce item they have over there that sounds like an engine.
 

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I read about BMW's balance rod solution that JM referenced. It's clever, no doubt.

But why not have one piston hitting TDC while the other hits BDC? That's how my Vee's 90-degree twin achieved balance without weights or rods. HD throws both pistons up and down together on their Vee, which creates their unique engine "experience."

I reject the inline twin engine for it's inherent design failures! All manufacturers should immediately cease and desist their construction forthwith and replace them with V-4s!
 

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Thanks to the BMW's PR Department

Man, was this written by the PR department at BMW? 700-800 lbs. sport tourers in the article you reference? Only one was over 700 lbs., at 730, the other two were below 700 wet, and of course none was 800 lbs.
This does look like a nice sedate sport tourer admittedly, enough power to get around, decent looking, and light enough to have some fun with. Too bad it's not easier to get at it's base price, though given it appear that doesn't even include luggage mounts, maybe that's not so practical after all.
 

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I read about BMW's balance rod solution that JM referenced. It's clever, no doubt.

But why not have one piston hitting TDC while the other hits BDC? That's how my Vee's 90-degree twin achieved balance without weights or rods. HD throws both pistons up and down together on their Vee, which creates their unique engine "experience."

I reject the inline twin engine for it's inherent design failures! All manufacturers should immediately cease and desist their construction forthwith and replace them with V-4s!
Big difference between a V and an inline Kenneth.

Harleys pistons stagger just a little due to the single pin crank giving it the potato sound.

I think think an inline would shake side to side like crazy if they did what you suggested.
 

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Big difference between a V and an inline Kenneth.

Harleys pistons stagger just a little due to the single pin crank giving it the potato sound.

I think think an inline would shake side to side like crazy if they did what you suggested.
Sure there is, all the designs have their own characteristics, benefits, disadvantages, etc. I was just hoping someone had the specifics as to why this engine was designed this way vs other I twins.
 

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One thing to remember is these are physically small bikes, if you are um... "econmoy sized" you ain't gonna fit..

When I had my GS in for a service they gave me one as a loaner and I felt like a circus bear riding a tricycle on it, YMMV but buyer beware..
 

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I thought the cylinders on Harley v-twins are kept in alignment by the "fork and knife" design of the connecting rods.
That's correct. No motorcycle engines are really smooth without some compensation. The V-8 engines or any higher multiple of 4, like V-12 or V-16 are pretty smooth. The V-6 is especially lousy and is used for compactness reasons not performance. An I-6 has better torque characteristics. The V-8 is better in every way. Motorcycle engines, having usually 2-4 cylinders are inherently nasty vibrationwise. The I-4 is really bad for high frequencies as witness my old CB750F and others before counterbalancing shafts came into use. It was a horrible dental drill at certain engine speeds, worse than almost any twin. The bike simply could not be ridden for more than a few minutes at those speeds (65mph unfortunately). The Harley style crank is actually a pretty good compromise as twins go.
 

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One thing to remember is these are physically small bikes, if you are um... "econmoy sized" you ain't gonna fit..

When I had my GS in for a service they gave me one as a loaner and I felt like a circus bear riding a tricycle on it, YMMV but buyer beware..
When I was deciding on the CB I watched the Honda design team video, which has a segment with a former Japanese racer riding around on it. When I saw the bike In person the first time I was shocked at how small it was. I didn't realize the racer dude must be about 4' tall and 90 lbs. It's false advertising I tell you!
 
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