I installed a S&S 475 (chain) cam in my 2018 Slim. During first test ride the engine developed a whistle or chirping noise coming from the A/C. So I tore it back down to check everything out. I noticed that the lifter bores have pitting in them during this last teardown. Is pitting like this a normal side effect of the casting process or did something mar my lifter bores. I can't confirm if these pits were there before because I never removed the lifters during install of cam.

I apologize in advance for the crappy photo. I can probably get better ones if needed.

 

That is not your noise from the air cleaner. Throttle bodies tend to make strange noises compared to carbs. It could simply be related to the cam - you also don't mention tuning - is it a lean spit/chirp.

The picture is terrible, if nothing is broken or there is major scoring in the bore and lifter, clean it up and run it. Your only other option is major teardown that most likely isn't necessary, and that wasn't your noise to begin with. It was most likely like that.

 

Running a tune for this specific cam from Fuel Moto via Powervision. Autotuned it...and it ended up adding a good bit of fuel during the autotune, so I don't think it's running very lean.

Strange thing about the noise from the A/C is that it was only there after warm up. I initially thought it was just air rushing over the TB blades causing a bit of whistle. That theory faded when I realized it was temperature related.

BUT, I am really just looking to see if anyone knows, for a fact, if stock lifter bores can have pitting from the manufacturing process. Nothing more, nothing less.

 

The chirp from the A/C is related to the cam timing and most likely. Just because the chirp is not there at start up doesn't necessarily indicate that the chirp is temp related; doubtful. Even with that auto tune, the motor is not completely dialed in; nothing to do with the chirp but worth mentioning; auto tune is no substitute for a proper dyno tune.

Don't sweat the lifter bore pitting; photo is useless. Check the lifters for scoring; lifters often see some scoring during initial break in but it's not an issue. Don't "borrow" trouble; ride the bike.

 

Can timing, I've wondered about that too. Like some overlap or something?
Sorry for the crappy photo, it's a tough spot to shoot . Bores are smooth and lifters move freely and are tight. After sleeping on it, I'm really realizing that debris couldn't cause pitting without causing some serious gouges as well...I think anyways haha.

 

Cam timing, I've wondered about that too. Like some overlap or something?
Sorry for the crappy photo, it's a tough spot to shoot . Bores are smooth and lifters move freely and are tight. After sleeping on it, I'm really realizing that debris couldn't cause pitting without causing some serious gouges as well...I think anyways haha.

 

Correct. I would think it's baked into the casting from the factory. I didn't see any pitting on my recent project.

 

hd cast isn't very good, hd needs a lesson from rice. that is typical for hd cast, seen worse. when they sand cast any impurity or out-gassing will cause a void which will show up when they bore through it, won't hurt a thing, just another place oil can be stored.