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CVO Technical => Twin Cam => Topic started by: Backroads3 on January 08, 2022, 08:51:23 AM

Title: Top End Noise 120ST
Post by: Backroads3 on January 08, 2022, 08:51:23 AM

 I replaced the 110" with a 120ST 37,000 miles ago. I've got what seems to be a prominent top end rattle mostly noticeable around 2200RPM. I read about Rockout rocker shaft inserts to help with top end rattle but wanted to ask if anyone has done this type or ideas on what could help. I have a 2010 FLXSE with 187,000 miles, had the trans gone through at time of engine swap and checked fasteners etc.

Title: Re: Top End Noise 120ST
Post by: HD Street Performance on January 08, 2022, 09:33:38 AM

The shafts can move and rattle but not in every case. That motor has some serious spring pressure, me personally I would change the springs and lifters. That said first question, is this rattle you hear worse hot or cold?

Title: Re: Top End Noise 120ST
Post by: ultra13 on January 09, 2022, 12:25:46 PM

Rocker Lockers helped my noise......

Title: Re: Top End Noise 120ST
Post by: Backroads3 on January 09, 2022, 04:53:41 PM

Thanks for the replies. The noise is about the same hot or cold.

Title: Re: Top End Noise 120ST
Post by: HD Street Performance on January 10, 2022, 10:51:44 AM

Try the lockers

Title: Re: Top End Noise 120ST
Post by: Backroads3 on January 10, 2022, 12:30:33 PM

I'll give them a try and let you all know the results.
Thanks!

Title: Re: Top End Noise 120ST
Post by: Backroads3 on July 24, 2022, 09:10:05 AM

I put the lockers in and it did help with the noise but unfortunately came back even worse. Upon inspection both cylinders were scored and the engine needs a total rebuild. At 40K it's very disappointing to say the least.

Title: Re: Top End Noise 120ST
Post by: HD Street Performance on July 24, 2022, 10:54:25 AM

And easily explained. Consider different pistons, not Wisco (HD) slipper skirts. KB forged, line2line coated pistons are a better alternative and using S&S cylinders to get to 124". It takes some juggling because the 120 rod is shorter than stock. Not a problem for an experienced shop.

Title: Re: Top End Noise 120ST
Post by: ultra13 on July 24, 2022, 03:28:01 PM

Sorry to hear this!