flitecontrol

I can understand them smoothing out at speed (so does a top), but why do they shake at idle?

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twocoolgliders

Isn't it the angle of the V?......pistons are not 180 degrees apart......so you get one cylinder firing, then the other, then a big space before the first one fires again.

Honda twin fires evenly.......same amount of crank rotation between firing, either cylinder. (Two cylinder engine should be either straight twin, or flat (boxer)......

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socalmarcus

Harley puts a lot into keeping the look, feel, sound, image, etc. of their bikes 'like a Harley.' They value their 'heritage' and so do their customers. It certainly isn't their pricetag. Remember that attempt to patten 'their sound?' If they wanted to design the engine for performance, quietness, smoothness they'd do it - just like everybody else can. They chose to keep push rods and carbs (up until recently) in their designs. Sure they could've counterbalanced more but they chose to rubber mount instead. Cheaper yes, but I think they want to avoid a well balanced engine - not their style.

IMO you can bet that what they are is what they were designed to be.

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Shadow Shack

Keep in mind the 88 B (Softails) and the V-Rod do not exert these traits, just the Sportsters and Dynas/FLH line.

All of the HD motors, save for the V-Rod, share a "slave pin" on the crankshaft...meaning both rods connect to the same pin rather than like the metric V2s on separate pins on the same plane. This is why the metric V2 jugs are offset, one is off the the left of the engine and the other to the right...HD twins have them in-line.

Throw in the narrow angle between the cylinders and the firing order --- one cylinder fires right after the other (rather than alternating one-fires-while-the-other-travels like the metric V-twins do) and you get the Harley-Harley-shake.

The B motor simply adds larger counterbalancers to quell the vibes, the V-Rod uses a more Honda-esque design in the motor (wider cylinder splay, alternate cylinder firing, etc), the rest of the line simply resorts to rubber mounting the engine.


But the irony of it all? Reflecting to what JunkyardDog has said about pushrod motors...take a TC88 motor in their heaviest bike (the Electra Glide Ultra Classic) and stack it against a 1500 Vulcan Classic or LC1500 Intruder with nearly the same displacements, with both metrics benefitting from liquid cooling (on the Vulcan), overhead cams/multi valves, and less overall weight --- and the TC will simply mop the floor with the metric bikes between the traps.

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JunkyardDog

Pushrods are definitely the way to go. Nascar gets 750 HP out of a normally aspirated 348 c.i. pushrod engine, with a single 4 barrel carburetor. No OHC, no FI, and no electronics. NHRA top fuel dragsters get upwards of 8,000 (yes, that's EIGHT THOUSAND) HP out of a supercharged 500 c.i. pushrod engine, with mechanical FI, no electronics. And they aren't even liquid cooled. Of course, they were only designed to run 1/4 mile at the time.


I have ridden metric bikes all my life, and admit I used to be a Harley hater, and I still have issues with HD motor company and HD dealers for the way they treated customers and potential customers back in the '90s and up until fairly recently. But the Japanese are now trying to do the same thing.

As for the bikes, I have grown to love the pre Twin Cam engines, for their simplicity, ease of working on, and have to admit I like the sound too. The Twin Cam bikes are nicer to ride, but they gained that at the expense of more complication, which to me was not worth it. Same thing with the counterbalanced engine. They made it smoother, while still having that great Harley sound. Fine. But again, more complication. Look at the problems the balancer causes on the Vulcan 750. Since it is not a Harley, I don't understand why they didn't just use offset crankpins, like was common Japanese practice at the time. The cylinders are already offset, because although they use a single crankpin, the rods run side by side rather than the "knife and fork" configuration Harley uses. By doing it this way, they could not only have eliminated the troublesome balancer, but the rubber mounting as well.

Harley's current engine is proof to me that you can update an ancient design, and make it work better than new designs. As for the FI, no engine needs FI, that's there just for the EPA. But I am looking for a pre Twin Cam Harley with a carb, so none of that matters to me. I will probably keep the stock specs, but will also probably rebuild it with better than stock quality parts. Ridden in a rational manner, it should last forever. Jerry.

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