Crank pin slipped

[05fatboy95]

Sorry for my lack of knowledge on sportster engines. All my experience is on twin cams. So any dumb questions I ask feel free to point them out!

My buddy has a 2001 sportster that he has put so much time and money into over the years yet it always seems to have issues and never really performed as well as what I think it should.

He took it to get dyno tuned at a dealer not far from us and they said it sounded like they could hear piston slap. It does have a little noise but it's not bad. (Even though they heard the noise they still tuned it and charged him $300 with out even a call first)

After talking to some others we didn't think it was piston slap so he took it to a local Indy who knows sporties.  "Bill is almost positive that it's a worn crank pin w grooves." Is the text I got.  Indy wants to tear it down and rebuild crank with new S&S rods.

Knowing nothing of sportsters does this sound right? Is this common? Recommend. Course of action for repair?

2001 1200
Big bore to 88ci
Rev. performance nikisil cylinders/Pistons
SE ported polished dual plug heads
CV carb
Andrews NV cam
11.3 comp
SE ignition mod.
96hp 92tq (seems low to me when I see 1250 kits doing better numbers)

[aswracing]

When the big end goes, they generally knock. The noise will sound deep in the motor.

Valvetrain and piston slap by comparison don't sound so deep. More of a clatter. Pretty common on these motors, and there are a number of different sources for it, there's no single thing.

If it does end up being a big end, do yourself a huge favor and fit up one of these:



The 1.5" pin essentially makes big end failures a thing of the past. The rods are strong ... as someone who's broken S&S's and Carrillo's both, I can tell you that these actually seem more durable to me. The big pin also reduces spread, which is the big, big issue with these cranks. When they spread, you get pinion runout, and pinion runout tears up the oil pump drive gear. A bad case of it will break the pinion shaft too.

The best thing about this crank though is the price. Very, very reasonable. Less than you'll spend rebuilding the stock one.

It's a bolt-in for 04+ bikes. It takes a little more work to get it into 91-03 bikes. Shoot me a note for more details.