Why do Harley Davidson engines rumble/shake?

J

Jay C

New member
I've noticed that HD engines "rumble" a lot more than import Big V-Twins. This is very noticable at idle. With aftermarket pipes, import and domestic V-Twins can sound similar, but the imports don't rumble/shake. Why?
 
And don't forget, a lot of the newer ones have rubber mounted engines, so it tends to isolate the engine vibration from the rider. You'll see the engine shaking like crazy but very little if any shaking transferring to the seat.
 
It's the firing order, it's the way Harley's were designed. As for being an old design, they may be, but so is the pushrod V8 engine, if it works and people buy them whey change a tried and proven thing.
 
all of the above answers are WRONG! this is the deal: Harley uses a COMMON CRANK-PIN which means that both pistons travel up and down TOGETHER AT THE SAME TIME! So all that weight is beeing thrown back and forth witch causes VIBRATION! It also is the reason for that distingt sound which is really a misfire! The new twincam has a chain driven counter balancer so not as bad. The only other bike to use a comman crankpin is the Honda Shadow Ace[American Classic Edition]which is an attempt to copy the Harley sound.
 
Old Harley engines were not balanced internally so they shook a lot. The newer (post 1999) are internally balanced and do not rattle near as much.
 
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