Good evening. I've been dealing with a noise that doesn't sound like it's normal twin cam noise. Today I took a video and noticed it's much louder on the primary side. The video does a surprisingly good job showing this. The noise seems like it's very unique, hopefully someone can identify it and tell me the source. Went as far as tearing down the top end to measure piston to cylinder clearance but if it's on one side then knock or slap can be pretty much ruled out, I would think:

https://photos.app.goo.gl/EhDJCDtwMRH1BNyt5

Here's the piston to cylinder measurements I observed, Taken without torque plates. If necessary I'll make one out of the old head and measure again. Any input would be great:

The pistons both measure 3.997 half an inch up from the bottom of the skirt.

Without torque plates, the rear cylinder measures 4.002 at the bottom, 4.0015 in the middle, and 4.0005 at the very top, front to back. Side to side, 3.999 bottom, 4.000 middle, 3.9995 top

The front cylinder measures 4.003 bottom, 4.002 middle, 4.002 top front to back. Side to side, 3.999bottom, 4.000 middle, 4.000 top.

 

A quick update: I see 86 people have viewed this post and none have replied. Thanks for viewing it, though.

So I measured the front cylinder under torque. I just bored a hole th the top of the OEM head and torqued it on the crankcase without the piston. measurements are:

With torque plates, the front cylinder measures 3.998 at the bottom, 3.998 in the middle, and 3.999 at the very top, front to back. Side to side, 4.000 bottom, 4.000 middle, 4.000 top

My clearance is 1-2 thousandths of an inch. Dead on. Perfect. Good job S&S!

I'm assuming that piston slap can be safely eliminated from the list of possibilities of the source of the noise?

 

cant read white letters

 

Are you saying the letters aare white on your display? Weird, I have it set to automatic
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A quick update: I see 86 people have viewed this post and none have replied. Thanks for viewing it, though.

So I measured the front cylinder under torque. I just bored a hole th the top of the OEM head and torqued it on the crankcase without the piston. measurements are:

With torque plates, the front cylinder measures 3.998 at the bottom, 3.998 in the middle, and 3.999 at the very top, front to back. Side to side, 4.000 bottom, 4.000 middle, 4.000 top

My clearance is 1-2 thousandths of an inch. Dead on. Perfect. Good job S&S!

I'm assuming that piston slap can be safely eliminated from the list of possibilities of the source of the noise?

 

Primary chain slapping around?

 

That sounds very similar to a noise Reaper's (2005 Softail with "B" engine) engine recently made. It turned out to be the sprocket on the front balancer rocking on the end of the balancer, because the "D" shaped balancer end had started rounding out... the only way to confirm it was to split the cases, unfortunately.

Hope your noise isn't the same cause.

Cheers!

 

Man, I checked it and its tight. I wish, though.

 

Thanks Clammy, I have a stethoscope that really hasn't helped me pinpoint anything, only makes the sound clearer. I'll try it again around the balancer and maybe it will reveal something. I don't care if I have to split the case. Did it to install the flywheel. I just dont want to do ti for nothing. But soon I'll have to if I don't find the source.

 

Even though my piston/cylinder clearance is good, I'm still getting these marks in my cylinders. I assume that since that's where the skirts are, it's normal?

 

Yeah, I could NOT isolate the sound with a stethoscope. It sounded like it was coming from the rocker box, then between the cylinders at the base, then from the lifter bore area, then from the crankcase. That sound travelled all over the place. It did sound louder on the front cylinder, though, and it turned out to be the front balancer that was on its way out. When the builder split the cases and showed me what had happened, he also said he'd never seen that before. The guy's been building engines since the Shovelhead days, and has been inside thousands of them, including plenty of Twin Cams.

That balancer failure sent chewed up metal through the engine and damaged the oil pump. It could also cause cylinder scoring.

Best of luck!

Cheers!