So, Ive returned to ownership of a Dyna Fat Bob! Not my first Fat Bob, and I got a darn good deal on it I think.

Thanks to Lets go Brandon's war on US energy, I tired quickly of filing my Diesel tank for $220 every 10 days. Hadnt been on a bike in 4 years, and hadnt been on a Harley for 8! Time to get back on 2 wheels, and I wanted another Harley.

I found and bought a 2007 Sportster 1200 50th Anniversary and it reminded me how much I actually enjoyed riding. While it was a fun bike, it was clear it wasnt nearly as good on the freeway at modern freeway speeds as a modern Big Twin.

I rreeaallyyy wanted a Dyna Low Rider S. But after a few solid weeks of research, I just couldnt get behind a SE110. Too much uncertainty and too many instances of hard failures. Plus, the Dyna S tax was still too much for me.

I found my Vivid Black 2013 Fat Bob at Roadrunner Harley with 20k miles. Previous owner installed a Heavy breather intake, Vance and Hines slip ons, Harley Mini footboards (LOVE THEM) and Daymaker head lights! I added the Reduced reach forward control kit because Im short. With the miniboards it feels very comfortable, even with the God forsaken factory drag bars. Just got the cables and hoses to install my 14" Wild1s which should make riding my bike 10000x more comfortable.

Plans are to pull the crank and get is adjusted and welded at Darkhorse and have the Dave Mackie Mega Sphere headwork and piston package installed. Probably next spring.

Love this bike!!!! Will get a pic uploaded tomorrow.

 

In glad you found the bike you wanted . Tell me though , as a new Dyna rider myself , why do you feel that it's necessary to have the crank welded ?

 

So, this certainly wont be every single Twin Cam, and your riding style will dictate if you even need to go this route.

Because of the crank being a pressed together unit, its much more susceptible to crank scissoring. This scissoring is what creates the excessive pinion and sprocket shaft runout which can destroy oil pumps (and the engine ) and primary drives.

In speaking with several people in the industry, THE #1 greatest factor for this to occur is lugging the engine.

Typically, excessive engine pinion/sprocket shaft runout and the damage those cause are seen more in Touring bikes than in Dynas and Sloptails. Simply the weight of the chassis, the typical load (2-up with full saddle bags) and how they are typically ridden (55-70 mph in 6th, rolling-on the throttle in 6th rather than downshift etc) are the biggest culprits.

Sudden shock loads like burnouts and clutch dumping are also big factors into what causes crank scissoring.

Darkhorse Cranks is the big player in repair of stock Harley pressed cranks. They have the capability of trueing pressed cranks, plugging the gun drilled crankpin, welding the crankpin to the flywheels, and balancing the assembly. It creates a solid and robust crank thats very strong and capable of taking hi performance loads without fear of scissoring that leads to excessive shaft runout which kills oil pumps then the engine.

Another major factor in Twin Cam longevity is upgrading to a Timken bearing setup. In 2003, Harley stopped using the Timken bearings to cut costs and complexity in engine production. For most riding scenarios, the pressed roller bearings are adequate.

I ride my bikes hard, and if Im pulling the crank for truing, then its a no brainer to have the Timken taper roller bearings installed.

 

depends on how you ride/ abuse your bike. If you take it easy on your bike, don’t worry about. Upping the power over stock with more than a set of cams... yea welding the crank probably isn’t a bad idea if you’re already in the engine doing performance work.

I’ll tell you I’ve ran the **** out of my 103” with 26k miles on it now and a little over 1k miles ago the crank runout was .004” when I had cams installed. Not perfect, but still certainly acceptable. We’ll see if it gets worse over time. Down the road when something needs done it’ll get trued and welded when it gets big bored.

 

Why bother with welding on a stock cast crank? Why not get a forged crank?

 

Ramjet Racing here in Phoenix builds a ton of fast Harleys. For the power level Im looking for, their recommendation of Darkhorse service on my crank will be good enough. And this is a shop thats on a first name basis with S&S.

 

Finally snapped a pic. The blank canvas to start with!



"... there are many like it, but this one is mine..."