I had my engine rebuilt prior to starting a long trip, and just under 500 miles in I developed a knock and was able to limp into Yuba City Harley-Davidson.

the bike ran fine except for the knock, and they determined it was coming from the front cylinder. The rocker box assembly looked fine so they pulled the head and cylinder and found a badly galled piston and damaged cylinder walls. I asked them to pull the rear cylinder just to make sure we knew it's state. It was also damaged though not nearly as badly as the front.

I also asked them to drain the oil and look for debris, but none beyond what you'd expect was found. I also had them open the cam chest but everything there looked in order.

The bike had about 55 PSI oil pressure at speed when hot (a higher pressure relief valve spring was installed). The pressure was about 20 PSI at wsrm idle. The idiot light consistently shut off about 3 seconds after firing up.

Based on information I gave them, they assess the problem is caused by improper break-in.

for break in, I ran the engine through three heat soak cycles and let it cool to room temperature between each one. I then rode gently about 27 miles to a tuning center, constantly varrying the RPMs between 2000 and 2500 and never exceeding that.

the shop then put the bike on their dyno, tweaked the fuel injection for a little while, and started doing hard pulls up to about 6250 rpm or so. When the tuner was done he proclaimed the engine was fully broken in now and I can ride it how I want but advised me to still be a little easy on it for a while.

attached are pictures of the damage to both pistons, one of which, the front, is much worse than the back. Also are pictures of the cylinder heads and of one cylinder. I've also attached a recording of the noise.

Interestingly to me is that the bike was only getting about 26 MPG, which I attributed to a new motor but don't know if that's the case.

My first, and the most important question is: could the damage seen on the front piston be the source of the noise? I ask because Harley wants to install new cylinders and pistons and send me on my way but I worry that that may not be the complete picture. I'm concerned that the damage to the piston might have been caused by something else, though their technician believes the rods are fine. The last thing I want to do is pay for a new set of pistons and cylinders and have exactly the same thing happen all over again.

secondly, would you agree that the break-in procedure used by the tuner is the cause of this problem?

Engine Details
2000 TC
100 inch S & S Big Bore Kit
S & S 570 gear drive, easy start cams
Screamin Eagle cam plate and oil pump
MM fuel injection

appreciate in advance your opinions and guidance.








Link to recording of noise:

 

Rebuild it right. Forget all the crazy dyno BS. Dive it moderately. It was broke in after your drive. Depending on how true and round, they got it, may have taken a little or lot longer but that is not why it tore up. Someone did not get the tolerances correct or overheated it and it seized.

Sure hope you were driving it when you say "for break in, I (? rent ?) a bike through three heat cycles and let it cool to room temperature between each one."

That front cylinder one is so bad, you can't even measure it now. You may be able to measure the back and see what they did.

That head has more than 500 miles on it. Just my opinion. A TC should never have over 10-12lb idle oil pressure if you ride in a warm climate. You cook the oil at stops and idle since the oil injectors are working above that. They should not work till at speed and of course, then the oil pressure comes up. That is for long life. That did not cause this either.

 

Had to fix the link to the video.

Thanks for your input.

I asssure you the entire engine has less than 500 miles on it.

 

Ripsaw, per my builder, my heat soaks were in my garage at about 1200 - 1500 rpm for a minute or two each, until the heads were hot to the touch - about 150 degrees.

In a nutshell, you're inclined to think this is improper assembly rather than the hard dyno pulls? I had Rotella T4 15w40 diesel oil in it for the break-in, and planned to switch to Red Line 20w50 at 1000k miles. Could that have played a role?

as a side note, I was getting 26mpg and I was riding pretty conservatively for the most part, cracking the throttle now and then but never for long and never above I'd say 4200 rom or so.

 

I have just been through this.
mine did the same, it was put down to, too tight piston to bore tollarence. Looked exactly the same, worse in the front and knocked.
The engine builder fixed it for free. Mine was about 200kms from memory, very little anyway.
As a comparison, the 2nd rebuild did a couple of heat sinks being careful. Then 200kms general riding, then off too Dyno. Dyno man said he would prefer 1000 kms before the Dyno. But he was happy to do some heat cyles and run in on the Dyno, then finish the Dyno tune. I said I didn't want max power, we all know it's new, don't go too hard on it. The Dyno sheet says about 5500rpm I think? It's now supposed to be running well and due to be delivered to me soon.

i know we want to get that tune done as soon as possible, especially like me with a poor base map, and no other option. But that Dyno guy seems to have gone real hard, too quick. It's basically a excess heat problem, new engines make lots of heat. Someone needs to try nut out if it was clearance, or Dyno hard running too soon that done it.
I'm not an expert, but I would guess flush the engine, new cylinders and piston set, and you will be good to go. I feel for you, like I said I've just been through this.
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Where was it tuned?

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Yes, who tuned it?

Also, what was the cruise air fuel ratio running at when she popped?

I've personally had this happen to me 3X before, and all three times it was too lean on the highway at cruise. Not WFO, not around town, interstate cruise around 70 mph. The tune goes lean, piston gets too hot, expands too much, and BAM! Now you've got aluminum shavings all over the oil system and about 25 thou clearance between the piston and cylinder wall (causing the knock at idle).

 

Just my opinion. Your heat soak did nothing. And serve no purpose.
The knock was the clack of the play in the big end crank bearings at the bottom and top of the throw as it reversed due to the gauled piston dragging metal to metal.
The engine was not put together correctly with proper clearances. Use Harley parts with the Teflon pad pistons if you want a quite engine.
6250 rpm sure did not help matters. Brand of oil had no bearing.
Are you wanting a drag racer for a few dozen trips or a 100K cruiser?

 

I don't want to mention the builder or tuner (2 different companies) and give them a bad reputation here. In my experience they are both good, honest people. I'll report back later how it gets handled.

They say misery loves company. Sorry you went through it but glad your builder took care of you. I hope like hell that mine will too. I had just started a 6,000 mile road trip, and am hoping to still make it happen this summer. I'd appreciate if you can check back here after you've got some miles on it and let us know how build #2 went.

If I'm interpreting the dyno sheet correctly (attached), then the AFR is pretty much 13.8:1 from 2,250 to 6,100.

This is exactly when it happened to me: my first longish haul at highway speed, about 90 miles. THREE times? How many engines have you had built??? That's terrible.

The purpose of the rebuild was to correct a failure we were never able to absolutely identify the source of: a knock, not similar to this one. As I explained to the builder, I want a reliable motor for long-distance riding, for fun in the local foothills, and for cruising around town.

 

I personally wouldn't run a new motor to 6250 on a dyno, with low break in miles; but I don't think that caused the issue here. To me, it's clearly a build issue with either out of round bores or just a poor piston to cylinder fit up. Check with piston manufacturer for fit up specs. That's a lot of metal that left those pistons, it's somewhere. If not splitting the cases, I would at least flush everything really, really well and pull the oil pump to inspect. Cut the filter open and see what's in there.

Good luck.