[ihasabike]

I rode someone’s road king yesterday and it had no vibration when traveling. A little when stopped, but not too bad. In contrast, the shadow Sabre I’ve been riding has enough vibration in the seat to make my back hurt, and my S40 is much worse. I’m wondering why there is no vibration with the RK. Is it the weight? The hard tail? Thanks.

 

[mike721]

Are you balancing your tires? Are they in good shape, inflated right, etc?

Pick a speed where it vibrates worst, then go that speed in 2 or 3 different gears, does the vibration stay the same or change? If it stays the same then look at tires, wheels, wheel bearings etc. If it changes, then it's your engine. Are these bikes carburated or injected? If carburated and you have multiple carbs, are they synchronized? I used to ride a Vstar, if the carbs were out of synch it vibrated so badly it hurt my feet on the boards, when synchronized it ran smooothly.

 

[ihasabike]

The road king owner said he has factory pipes, and he thinks the after market pipes on the shadow saber are the cause of the vibration. Could he be right?

 

[Friedl]

Your S40 is a single-cylinder 650 built with old, but proven, technology. They vibrate - I had one.

 

[cmonSTART]

Also the Road King is a very well balanced, refined machine. HD put a lot of effort into controlling vibration and making sure the rider doesn't feel it while cruising.

 

[Major Sphincter]

I, being the proud owner of both a FLHS (the predecessor to the Road King) and a Road Glide, am pleased to interject. The two bikes I listed and the Road King are all FLH(T) series bikes so are basically the same machines. ("F" big engine, "L" large front fork tubes, "H" or "T" full conventional rear suspension) First they are not hard tails or soft tails but full suspension type MC's. There are many models of HD that are soft tail like the fat boy for one, but, none of them are true hard tails. They might look like a hard tail but that rear end has a pivot and shock.

There are many things HD does not do all that well but going straight and smooth is one it does do well in spades. I am sure the weight has something to do with it as if creates great inertia but the FL front end is the primary reason in my uninformed opinion. On both of the bikes I've owned I could set the throttle lock or cruise control at any speed obtainable and run with no hands until I ran out of gas. (Not that I would ever do such an unresponsible thing.) The flh's are true cruisers and that is what they do.

 

[RonK]

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To find out if it's your engine causing the vibration, get up to speed on a smooth road, then pull the clutch in and coast with the engine idling. If the vibration goes away, then your engine is the problem and you can't do anything about that other than ride at a different speed where it's the smoothest.

If you have the problem still, then it could be the tire balance, loose forks, or something else. Hard to tell there.

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