Author Topic: 4.375 stroke 4.125 pistons?  (Read 298 times)

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Offline BVHOG

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4.375 stroke 4.125 pistons?
« on: September 16, 2018, 08:51:54 AM »
So who has pistons available for this application and how have the 107 cylinders been holding up?  Would prefer something with line to line coating but will get that done if need be.  I see T-man has something like this but I have never been a fan of Wiseco pistons.
« Last Edit: September 16, 2018, 12:45:39 PM by BVHOG »
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Offline rigidthumper

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Re: 3.875 stroke 4.125 pistons?
« Reply #1 on: September 16, 2018, 09:56:12 AM »
4 1/8" bore X 3.875" stroke is a 103.6" engine. Diamond can custom make them for you, John @ JWperf is a dealer.

Offline DTTJGlide

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Re: 3.875 stroke 4.125 pistons?
« Reply #2 on: September 16, 2018, 10:47:42 AM »
I'm thinking you're talking about 4.375 x 4.125 pistons since you're in the M8 section, the pistons that T-man is using are Wiseco Black Edition, I'm pretty sure they are using a different ring pack than the ones that were problematic previously. They are what I'm thinking of going with this winter, most likely just going 114 as I'm looking more for longevity & not having to spend the extra dollars upgrading TB, clutch,etc. I think they have a better ring pack & are coated vs the HD mahle pistons, I also trust T-man to pick a high quality piston.

Offline BVHOG

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Re: 3.875 stroke 4.125 pistons?
« Reply #3 on: September 16, 2018, 12:47:59 PM »
4 1/8" bore X 3.875" stroke is a 103.6" engine. Diamond can custom make them for you, John @ JWperf is a dealer.
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My bad. Corrected the numbers. 117
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Offline HD Street Performance

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Re: 4.375 stroke 4.125 pistons?
« Reply #4 on: September 16, 2018, 02:14:50 PM »
Why not KBs? Forged.

Offline BVHOG

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Re: 4.375 stroke 4.125 pistons?
« Reply #5 on: September 16, 2018, 03:58:54 PM »
Why not KBs? Forged.

Havenít seen or heard of anything readily available at this time. They would be my first choice
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Offline HD Street Performance

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Re: 4.375 stroke 4.125 pistons?
« Reply #6 on: September 16, 2018, 04:04:53 PM »
CP has a shelf piston, I just bored a set of them. How about Mahle?

Offline Ohio HD

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Re: 4.375 stroke 4.125 pistons?
« Reply #7 on: September 16, 2018, 04:14:19 PM »
Best as I can tell the OEM compression height is 1.143". Here's a CP number for 4.125" bore.


BHM8117-FT
2017 Harley Milwaukee Eight 117 cu in, 4.125 bore, 4.375 stroke, 10.75:1 C/R, 1.143 C/H, -1.3 dome ccís
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Offline jbroski

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Re: 4.375 stroke 4.125 pistons?
« Reply #8 on: September 17, 2018, 07:22:56 AM »
I run axtell/JE pistons with great results.

Offline Durwood

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Re: 4.375 stroke 4.125 pistons?
« Reply #9 on: September 17, 2018, 07:30:02 AM »
CP has a shelf piston, I just bored a set of them. How about Mahle?
The cylinders look great too Don. :up: Thanks

Offline joe_lyons

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Re: 4.375 stroke 4.125 pistons?
« Reply #10 on: September 17, 2018, 09:50:52 AM »
KB is going to be making some Pistons soon.  when I talked to them last they're going to have a couple of bore size options with Builders Pistons with high compression domes that can be milled down to suit your compression needs.    they also said that they will be providing a sheet showing what the cc's of the Piston will be in different increments of Milling.
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Offline HD Street Performance

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Re: 4.375 stroke 4.125 pistons?
« Reply #11 on: September 17, 2018, 10:01:43 AM »
That will be my go to. Thanks