My 103" motor blew a head gasket and in the tear down process, found that the crankshaft runnout was .019". This resulted in damage to the cams, cam plate and oil pump along with visible scuffing on the piston skirts and cylinder walls. The motor had about 30K on it and about 30 months. In the build process I didn't scimp on parts to cut costs and had them install what they recommended would go with the build from top to bottom. Now, the Service Manager at the H-D shop that did the build said it was probably due to my lack of proper maintenance so it is no fault of theirs.
I'm not inclined to think that the crankshaft runout occurs over time but rather is a manufacturing problem.
Can someone give me some insight on this?

 

Without knowing the details of the build, even assuming that you don't beat on the bike; it is impossible to say what caused the wheels to slip. **** happens; it happens on stock and modified engines without discrimination.

Was the runout checked before the build? This is an important bit of information. If the runout was excessive before the build, the crank shoudl have been trued and welded as part of the build process.

Cranks can slip for a variety of reasons; a panic stop without pulling in the clutch lever; a sudden downshift from high rpms; a nasty heat soaked hot start kick back; attempted wheelies; burnouts; the list goes on.

The crank pieces are assembled via an interference fit. If manufacturing tolerances are off, a "loose" crank assembly is more likely to shift than a tightly fitted crank when subjected to stress loads.

Runout can increase over time; that is why runout shoud be measured before any performance upgrades are done. That is the baseline and can be checked as the miles roll up to see if it is increasing and steps can be taken to avoid the situation you currently find yourself in.

Lack of proper maintenance probably was not the cause of the failure.

Sorry for the bad luck.

 

It is not a maintainece issue as dj has already mentioned, but rather a manufacturing issue, that the Moco tried to sweep under the rug via increasing the "accepted" TIR on the crank specs when they saw this problem raise it's ugly head.
Hard to believe your local dealer has not seen/heard this prior.
Those cranks are pressed together, and if the interference fits are not correct, then the press fit itself has resulted in occurances such as yours.
The way in insure that will not occur is to weld the crankpin to the flywheel half, on both sides.
We do it, S&S offers it when they sell a crank assembly, and Darkhorse Crankworks, Newton, Wis., will weld, and "pro-plug" them as well which is usually SOP.
Too bad that the shifted wheel halves gobbled up those parts.
Hope it works out, but if we can be of service in regards to the repair, feel free to contact us anytime.
Scott

 

That sucks! It's to bad the Moco doesn't fix the known problem like the aftermarket performance company's do.

 

Like the others have said, this is a very well known problem due to inferior design by HD. That service writer was lying through his teeth and he knew it. He was just trying to pass the buck. I'm not entirely sure why, as the bike had 30K on it and they couldn't reasonably be held liable for the problem.

 

Details on the parts are: Crank was a JIMS. The build was a 103 stage V by Patriot Harley of Fairfax, VA. The big bore package is still advertised on their web page.
The Service Manager told me that dyno tuning it up to 108h/121t was one of the things that probably caused it too.
My riding style was more at highway speeds touring. Not a bar hopper, no wheelies or burnouts. Oil changes were always at about the 3K mile point with filter change as well.
I don't know if improving the output by the dyno tune really is a factor in this. Patriot did an initial dyno tune then after the 1000 mile break in, they did another tune and it produced 96h/101t.

 

That seems very odd.
Not trying to be a wise guy, but if dyno tuning their engine combo caused the problem, (1)why do they build those, and (2)why do they tune them?
Me thinks the service manager has taken a night class in BS 101.
Scott

 

I agree with Scott. on this one why??????? We have built many engines and if I read this right they used a SE spec crank made by Jims to SE specs.
Forge crank I beam rods did they not change the bearing? Thous... cranks from what we have seen right out of the box has about 1.5 thou or less run out.
That crank can handle more than that. Some thing does not sound right.....
We have used the SE crank/ Jims with weld, pin, Hbeam rods done in house or sent out etc.,etc., handle 200 hp plus..... with blowers no issues

Again something does not sound right...... Maybe installed wrong.....

 

When it dropped 12hp & 20tq in 1000 miles they would have been tearing that sob apart if it were mine...I agree with Scott & Drago don't drink their "kool-aid"

 

OK, help me out here. Are you saying that the inital dyno tune made 108HP/121TQ? And the follow up tune at 1000 miles made 96HP/101TQ? Is that right?