HarleyTechTalk

Technical Forums => Twin Cam => Topic started by: Eglider05 on October 25, 2011, 01:58:53 PM

Title: Dished Pistons
Post by: Eglider05 on October 25, 2011, 01:58:53 PM
I'm in the process of doing some research for a possible 107-117 build. Can anyone give me specs on the negative dome sizes available (i.e. -2cc)? I'm trying to figure out a way to get my compression where I want it without messing with the heads and want to know what my options are.

Thanks,
Rick

Title: Re: Dished Pistons
Post by: rbabos on October 25, 2011, 02:29:08 PM
Quote from: Eglider05 on October 25, 2011, 01:58:53 PM
I'm in the process of doing some research for a possible 107-117 build. Can anyone give me specs on the negative dome sizes available (i.e. -2cc)? I'm trying to figure out a way to get my compression where I want it without messing with the heads and want to know what my options are.

Thanks,
Rick
Head Quarters has CP -7 cc dished pistons for the 107
Ron
Title: Re: Dished Pistons
Post by: Eglider05 on October 25, 2011, 04:00:50 PM
Quote from: rbabos on October 25, 2011, 02:29:08 PM
Quote from: Eglider05 on October 25, 2011, 01:58:53 PM
I'm in the process of doing some research for a possible 107-117 build. Can anyone give me specs on the negative dome sizes available (i.e. -2cc)? I'm trying to figure out a way to get my compression where I want it without messing with the heads and want to know what my options are.

Thanks,
Rick
Head Quarters has CP -7 cc dished pistons for the 107
Ron

Good info thanks. That would put me right at 10.0 on a 107 with my 84cc heads. Is there a down side to the dished pistons?

Rick
Title: Re: Dished Pistons
Post by: rbabos on October 25, 2011, 04:29:45 PM
Quote from: Eglider05 on October 25, 2011, 04:00:50 PM
Quote from: rbabos on October 25, 2011, 02:29:08 PM
Quote from: Eglider05 on October 25, 2011, 01:58:53 PM
I'm in the process of doing some research for a possible 107-117 build. Can anyone give me specs on the negative dome sizes available (i.e. -2cc)? I'm trying to figure out a way to get my compression where I want it without messing with the heads and want to know what my options are.

Thanks,
Rick
Head Quarters has CP -7 cc dished pistons for the 107
Ron

Good info thanks. That would put me right at 10.0 on a 107 with my 84cc heads. Is there a down side to the dished pistons?

Rick
Not that I'm aware of . But I've only used one set.
Ron
Title: Re: Dished Pistons
Post by: rob71458 on October 25, 2011, 05:57:48 PM
What about the loss of squish (quench), with a dished piston?
Title: Re: Dished Pistons
Post by: glens on October 25, 2011, 06:42:43 PM
Why would there be a loss of squish?  The perimeter is still full height, no?
Title: Re: Dished Pistons
Post by: rob71458 on October 26, 2011, 06:05:39 AM
Yes, but I would think it's not going to be as effective as a flat top. Lets see what the Pro's have to say.
Title: Re: Dished Pistons
Post by: DBC on October 26, 2011, 07:45:32 AM
There is nothing wrong with using a dished piston.
Title: Re: Dished Pistons
Post by: Eglider05 on October 26, 2011, 09:03:37 AM
Does anyone have any info on what's available in a 117" dished piston?

Thanks,
Rick
Title: Re: Dished Pistons
Post by: rbabos on October 26, 2011, 01:46:08 PM
Quote from: Eglider05 on October 26, 2011, 09:03:37 AM
Does anyone have any info on what's available in a 117" dished piston?

Thanks,
Rick
If I'm not mistaken some of the builders take a flat top and dish them to suit. That might be one option.
Ron
Title: Re: Dished Pistons
Post by: Eglider05 on October 26, 2011, 02:34:09 PM
Quote from: rbabos on October 26, 2011, 01:46:08 PM
Quote from: Eglider05 on October 26, 2011, 09:03:37 AM
Does anyone have any info on what's available in a 117" dished piston?

Thanks,
Rick
If I'm not mistaken some of the builders take a flat top and dish them to suit. That might be one option.
Ron

That's my understanding as well. I'm just trying to figure out how far they can go with the various piston sizes.

Rick
Title: Re: Dished Pistons
Post by: Powerglides on October 26, 2011, 03:21:49 PM
The HQ 107 pistons are a flat top. They also have a corrected compression height that brings them flush with the top of a bored out OEM cylinder when using a stock 96" crank. You will be around 10.5 compression with the HQ .030 head gaskets and 84cc chambers.
I believe that their 113 pistons are -7cc.
Title: Re: Dished Pistons
Post by: Hillside Motorcycle on October 26, 2011, 05:52:45 PM
Quote from: Eglider05 on October 26, 2011, 09:03:37 AM
Does anyone have any info on what's available in a 117" dished piston?

Thanks,
Rick

Up to 5cc's can be pulled from a J&E 4 1/8" flat top, and still maintain proper dome thickness.
J&E also has them available in a minus 10 cc's. :smile:
Scott
Title: Re: Dished Pistons
Post by: rbabos on October 26, 2011, 06:09:59 PM
Quote from: Powerglides on October 26, 2011, 03:21:49 PM
The HQ 107 pistons are a flat top. They also have a corrected compression height that brings them flush with the top of a bored out OEM cylinder when using a stock 96" crank. You will be around 10.5 compression with the HQ .030 head gaskets and 84cc chambers.
I believe that their 113 pistons are -7cc.
That's correct. I was looking in the wrong kit. :doh:
Ron
Title: Re: Dished Pistons
Post by: Eglider05 on October 26, 2011, 06:20:57 PM
Thanks a lot for the help guys. This info helps out a lot, especially finding out I can go up to -10 if needed.

Thanks,
Rick