Custom/Hybrid big bore engines knocking sound?

[dmpus]

Hey guys, I and my buddy have big bore motors built by different builders. Both of them have this knocking sound that causes bigger vibration than a stock 701. The stock 701 runs much smoother and with less vibration. Is that sound normal and common for big bore engines?. What's th feedback on your BB engines
Thanks!

 

[OCD Solutions]

My SS865 lopes like a bigblock V8 at an idle but smooths right out under throttle. I reported the same knocking as you when I first got it but don't even notice it now so I either got used to it or it went away.

Are you sure that you are not making contact somewhere like the pipe chamber to the side of the hull or front left engine cradle? Banging the keepers on the front case?

 

[dmpus]

I pulled coupler off, Kenny keepers off, all cleared plus another ski with different bigbore makes identical sound... I guess ill have to live with it, just not used to it coming from stock smooth 701

 

[OCD Solutions]

You can't hide power. :bigok:

 

[kevbo]

It could also be the chamber hitting the head pipe under the coupler. The last major rattle I had was the chamber hitting the front mount.