Dull knocking sound
 

Hi guys. New shovelhead owner here. It’s a 1980 Flh supposed to be a low mileage but who knows! The screws on right hand side of the engine have never been touched. Couple of oil minor oil leaks but nothing serious. My question is that I have a dull knocking that sounds like piston slap on acceleration especially between 40 and 50 mph. Is a small amount of piston noise acceptable on a shovel? I don’t have another shovel to compare it to. Ireland is a strange place, nobody seems to want to help out. I’m not new to Harley Davidsons or motorcycles and I always do my own work. Thanks

Another guy from Ireland is on the site and just finished a very nice 75 i believe if your some what close maybe he can give an earn on the same page your on

with out hearing it no one can tell you whats up

I do understand. I can’t really record the noise as it only happens when I’m riding. I really need to ride a couple of other shovelheads to know what is normal and what’s not. I don’t want to pull it down to find out nothing is wrong. It starts and rides well.

If a crank pin roller set has worn the crank pin in one spot ( this is how it starts ) - then while in hi gear at 50MPH or 88 klm - slightly roll back on the throttle just a bit to remove the engine load on the bike - if you hear a rattle then the crank pin is damaged from wear - flat level road is best

it will come in and go away with slight throttle movement at that spot - that is the beginning of real damage to come - take it apart

Strange noise
 

I have a 75 that had near the same sound . I tracked it down to a worn compensator . I chucked it up in my lathe and took a .015 cut on the end of the “bolt” to allow it tighten a touch tighter . Sound was gone and never returned after the fix .

I went over the engine with a home made stethoscope last night and front and rear top ends make the same tapping clicking sounds, barrel and bottom end sound quiet. Intermittent knock or slap in primary. Chain is adjusted properly and engine nut was removed cleaned and torqued about 700 miles ago.
I have a chance to ride another shovelhead in the next month or so so I can compare noises.
One thing. Could the sound in hearing be induction noise? Thanks for all the help.

being sincere here......is everything on the bike done up tight as in something might be falling off soon? or like i have experienced, something has cracked like the top motor mount or the muffler mount, or the coil mount or the rear light bar has come loose.

had the coil and top motor mounts break. also the exhaust threads stripped out of the heads

Worn front Nanner caliper pin will give a sound as if the bottom end is coming out,

May not be what you have for brakes though,

Just throwing that out there,

Yeah, it does rattle but even when I cover the front brake it still happens.
What makes me think it might induction noise is that the noise increases the wider the throttle opening. I’m going to remove the air cleaner and see does it change the sound.