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[JKM]

I'm no builder, but I think 5-6 thou is the max.  HD widened the spec a to I believe 12 thou, but was previous 6 thou

[grc]

On the previous Big Twin's, up until 2007, the runout service limit was 0.003", and the typical new flywheel assembly (crankshaft) was usually less than 0.001" out of the box.  After Harley changed the design for 2007, and the process by which they assembled the crankshaft, they experienced a very large number of failures.  In typical Harley fashion, they first buried their heads in the sand, then they denied knowing anything about a "problem", then they arbitrarily changed the acceptable limit for runout as measured in the cases to 0.012".  As any mechanical engineer can tell you, that is not an acceptable amount of runout, but we have to understand this decision was never about meeting engineering standards or customer satisfaction.  This decision was strictly based on saving the MoCo massive amounts of money.  From what I've read it seems the typical new Big Twin now comes from the factory with runout at the pinion shaft in the 0.004" range.  In other words, the new ones come with runout that was considered at or beyond the service limit eight short years ago.  This is not how I define progress.

Jerry

[Rooster]

Jerry is right. I bought my 07 and the shop manual and it states max pinion runout .003 and a few months after they announced .012 is the new .003. Wonder if the new manuals reflect the new .003. Anyway I haven't found a motor builder that would accept any more than .002 less would be better. I don't understand even though I know the reason. Seems the MOCO doesn't want us to actually ride our bikes. ok done for now

[laylonlor]

how much  hp ya getting out of the ss 124 motor, and are the heads cam  OK?    

I suspect you have too many zeros and it's actually .006". Thats pretty close to average on the late models I see here in the shop. At the stage 3 level, you are increasing power substantially and adding more stress to the crank substantially. If you have not already paid for all these parts for the stage 3 I would very strongly consider going with an S&S crate 124. They're damn near bulletproof out of the box, run quieter, make great, real world, useful power that can be increased even further if you want more later on, they're available in granite CVO color now and they damn near pay for themselves in the cost savings you have in labor over building a motor that is going to put out the power in the same ballpark as the S&S and to add a little more icing to the cake, they have a warranty that they actually stand behind! All you have left to address is the throttle body, injectors, tuner and a clutch and you're there! And as required to be a vendor here, Id be more than happy to set you up with everything and a great discount. Yo add to that, you can sell your heads cams and some of the other stuff that are still desirable for other guys doing builds to help fund the whole thing.

Edit: If you decide to build what youve got, I would either get a set of S&S flywheels and replace yours with the increase in power you intend to make or send your to Darkhorse to be reworked. You didnt say if this is an A or B motor. If its a B without question I would do something to the bottom end. The interference (press fit) sprocket on the crank to drive the cain to run the counter balancers are weak. They will move if you put the power to them them and your motor will be out of balance. The factory setup has no splines, no woodruff key, no flat slide, nothing to help keep it from spinning out of time. Big POS.

[INDEPENDENT_1]

how much  hp ya getting out of the ss 124 motor, and are the heads cam  OK?

On who's dyno? Heads are good but there's room for improvement.

[Steve Cole]

From what I've read it seems the typical new Big Twin now comes from the factory with runout at the pinion shaft in the 0.004" range.  In other words, the new ones come with runout that was considered at or beyond the service limit eight short years ago.  This is not how I define progress.

Jerry

I would have been happy with that........... my 2014 got 50 miles on it before we tore it down to start testing camshafts. Once in there why not measure things? Well to no big surprise 0.0095" was the crankshaft run out from a box stock engine! Moco says 0.014" is now AOK.

[Jswerve]

I would have been happy with that........... my 2014 got 50 miles on it before we tore it down to start testing camshafts. Once in there why not measure things? Well to no big surprise 0.0095" was the crankshaft run out from a box stock engine! Moco says 0.014" is now AOK.

Yuk. I had .00625 wasn't impressed

[twinotter]

Hell, if Briggs & Stratton can make a crank with no runout, surely Harley could too, if they actually gave a sh..t. My father used to rebuild Gravely tractor crankshafts with a big brass hammer and a square!! he got the ends truer than HD does (his rebuild typically lasted 10-15 yrs).
The constant pennypinching, and substandard materials/ workmanship that wouldn/t be passed in Tiawan so the CEO can get a fatter bonus. I won't be buying a new Harley any time soon/ maybe never. HD is going back to its roots, alright --- AMF!! (Another Motorcycle F>>>ked up).fwiw jm2c Twinotter

[charles05663]

With all of the precision CNC machines today I would expect things to get better and not worse.

 

[Twolanerider]

I would have been happy with that........... my 2014 got 50 miles on it before we tore it down to start testing camshafts. Once in there why not measure things? Well to no big surprise 0.0095" was the crankshaft run out from a box stock engine! Moco says 0.014" is now AOK.

.014" of wobble (no other way to describe it when that large) is now the accepted spec?  Guess they don't care that such a spec isn't just bad it's actually embarrassing.

Interesting comparison just this evening had occasion to be in the cam chest and have the primary off an 88" engine still of the vintage with the good left side bearing.  Right side run out was .0005 and left side was .001.

Guess that means that a decade or more ago Mother Harley still had to buy decent dial indicators to do these measurements.  Now they can get by with tape measures, yard sticks and a guy with a pretty close RX for his glasses.

[Steve Cole]

Yes, its sad that they cannot hit the numbers they use to, but they feel it's OK and doesn't cause issues, I guess. Funny thing is when I used to work with the factory when one of the big wheels rode a custom engine build bike we did for them he asked what did we do to get it to be that smooth out of a hot rod build? When we informed him he look surprised about it and said in there testing ........ and I told him to stop right there I didn't want to hear it. You asked and I told you but if you want to chose to ignore it that's up to you. Any guesses which route they took?

[Jswerve]

Yes, its sad that they cannot hit the numbers they use to, but they feel it's OK and doesn't cause issues, I guess. Funny thing is when I used to work with the factory when one of the big wheels rode a custom engine build bike we did for them he asked what did we do to get it to be that smooth out of a hot rod build? When we informed him he look surprised about it and said in there testing ........ and I told him to stop right there I didn't want to hear it. You asked and I told you but if you want to chose to ignore it that's up to you. Any guesses which route they took?

The cheapest!

[Fired00d]

Yes, its sad that they cannot hit the numbers they use to, but they feel it's OK and doesn't cause issues, I guess. Funny thing is when I used to work with the factory when one of the big wheels rode a custom engine build bike we did for them he asked what did we do to get it to be that smooth out of a hot rod build? When we informed him he look surprised about it and said in there testing ........ and I told him to stop right there I didn't want to hear it. You asked and I told you but if you want to chose to ignore it that's up to you. Any guesses which route they took?

This...

 
Ride Safe,
Fired00d
 

[prodrag1320]

Connecting rod play will cause scoring of the cylinder walls, excessive flywheel play (run out) will cause all that and more.....

not really accurate.about the only time a lower end is going to cause cylinder scoring is if the rod bearings going south and debris from that causing scoring.a lower end being way out of true would damage oil pumps & cam plates,but would have little effect on scoring cylinder walls

[phato1]

I know crankshaft runout will ruin the oil pump ect... but thought connecting rod play might cause lateral movement of the piston within the cylinder.