I own a 1972 FLH. Completely stock except for an S&S Super E, and a brand new electronic ignition. This may be a silly question, but this is my first shovel, so I figured I should ask: When I roll on the throttle and hit near the top speed (80ish), it vibrates so bad it's hard to keep my feet on the floorboards. I know it's a shovelhead, rigid mounted, etc., but is this normal for a shovel? I have the rev limiter on the ignition set at 5400rpm. Would hitting that cause this vibration? Thanks in advance, - Danny

 

Many things cause vibration. Loose motor mounts, especially the top, bad tires, unbalanced wheels, bad bearing in wheels or swing arm, the list goes on.

 

I'd inspect the motor mounts first, since you say you only notice it at the upper end. Then pull the wheels and get them balanced.

 

I will bet it is a loose or broken top motor mount. If you have the one piece style and want to keep it make sure it fits properly or shim it to fit. Whether it is broken or not, if it is the one piece style I recommend tossing it and get a two piece mount. A loose or incorrect fitting top mount will break itself or break the frame tab that it mounts to. You don't need to ask how I know that. Minor vibration changes is the bikes way of letting you know you need to adjust your chains or some other item needs maintenance, but hammering vibration is more than likely your motor mounts.

 

By the way, up to about 75 mph, my Shovel is smoother running and less shake than my 06 Dyna.

 

My '83 FLHS was the way at anything above 60mph. Discovered the nut holding the primary belt gear on the transmission output shaft was loose. After it was tightened and the output shaft oil seal replaced the vibration was gone. Ride safe.

 

Thanks everyone for the suggestions! From the way it sounds, I think it's most likely the primary chain. But I'll check everything. I feel like a broken motor mount would be a lot harder/aggressive vibration than it is. But I'll check that too.

 

Things not mentioned. Check the clutch hub to see it is mounted on properly. Loose chains can cause high speed vibes. A "raced" flywheel will shake too but through all rpms usually.
Motor mounts have been mentioned, but I didn't see broken frame. Check the swingarm for looseness in the frame mounts. Neck bearings get loose too. Not likely your issue, though. But could contribute.
Look at the oil for shavings. The rod bearing separators can become worn to let the bearings move out of position and let the rods throw balance off. Not likely in your case, but it has happened.
In other wards give the entire bike a good going over. You don't know the history or care given by the previous owner.

 

I know some of the history. For nearly all of it's life it has been a show bike. Started out as a dresser, then the previous owner bought it in 1990 something, stripped it down, painted it, made repairs, etc., and had taken to a couple shows every year since then. Very well taken care of. I saw his bike collection and his shop. New top end rebuild before I bought it. He has been building bikes since 1971.