Boring vs Piston Cyl. Kit
Thread Starter
|
Road Captain
Joined: Dec 2014
Posts: 713
Likes: 131
From: Fl
Boring vs Piston Cyl. Kit
I've always heard it's best to bore with pistons on hand. That was a long time ago and I'm wondering if it changed with the new tech. Are the kits bored to match each piston or is it assembly line style?
Thread Starter
|
Road Captain
Joined: Dec 2014
Posts: 713
Likes: 131
From: Fl
From S&S
"S&S 4-1/8" pistons are machined to such close tolerances that it is not necessary to measure the piston. Additionally, the low friction coating on the piston skirt of early production pistons without micrometer window makes taking measurements very difficult. Therefore, hone cylinders to nominal diameter +/- 0.0001" for correct clearance. Current production pistons have micrometer windows in the coating on the piston skirts that allow accurate measurements to be taken. These pistons may be installed by honing cylinder to nominal diameter +/- 0.0001" or by measuring piston and honing cylinder to achieve .002" - .0025" close clearance for street applications or .0032" - .0045" loose clearance for immediate competition use."
"S&S 4-1/8" pistons are machined to such close tolerances that it is not necessary to measure the piston. Additionally, the low friction coating on the piston skirt of early production pistons without micrometer window makes taking measurements very difficult. Therefore, hone cylinders to nominal diameter +/- 0.0001" for correct clearance. Current production pistons have micrometer windows in the coating on the piston skirts that allow accurate measurements to be taken. These pistons may be installed by honing cylinder to nominal diameter +/- 0.0001" or by measuring piston and honing cylinder to achieve .002" - .0025" close clearance for street applications or .0032" - .0045" loose clearance for immediate competition use."
Club Member
Joined: Mar 2016
Posts: 11,688
Likes: 22,273
From: Clearwater, Idaho
Personally, I would never install a cylinder/piston set without verifying proper clearances, no matter what any manufacturer says. And yeah, If I were having cylinders bored, I would have the pistons on hand to verify that everything is indeed "up to snuff".
Sponsor
Joined: Dec 2007
Posts: 12,084
Likes: 829
We bore cylinders constantly here, in various engines, from T/C to Flatheads.
We always, repeat, always, measure skirt diameters.
If you know how to measure a piston, the non-coated piston(which has been forever) presents no problem whatsoever.
That window is no different than one needing a sign to tell you to slow down on a curvy road........common sense.
Scott
We always, repeat, always, measure skirt diameters.
If you know how to measure a piston, the non-coated piston(which has been forever) presents no problem whatsoever.
That window is no different than one needing a sign to tell you to slow down on a curvy road........common sense.
Scott
Banned
Joined: Sep 2009
Posts: 3,569
Likes: 624
From: deland,florida
I would never buy a kit where the pistons are not the EXACT set the cylinders where bored for,we`ve seen a fair amount of failed "production"cylinders here,or at least have them torque plated & checked by someone with the proper equipment
Last edited by prodrag1320; Oct 20, 2016 at 05:55 AM.
Road Captain
Joined: Jan 2014
Posts: 566
Likes: 70
From: The Redneck Riviera
Whatever brand of Pistons that you choose, 'recommend Pistons with a 3mm Oil Ring, and Nitrided Oil Rails in the Ring Pack...
Trending Topics
Thread Starter
|
Road Captain
Joined: Dec 2014
Posts: 713
Likes: 131
From: Fl
*Mahle Pistons feature
*Forged from 4032 aluminum alloy for tighter cylinder wall clearances and quietier operation
*Forged 4032 alloy with grafal anti-friction coating on skirts
*Phosphat-coated to reduce micro-welding and pin galling
*Pin bores finished on CNC boring equipment
*High strength 9310, light weight nitrided steel wrist pins
*1.5mm plasma moly top rings, 1.5mm napier cast second rings
*3mm low tension oil rings
I like the tight fit.
*Forged from 4032 aluminum alloy for tighter cylinder wall clearances and quietier operation
*Forged 4032 alloy with grafal anti-friction coating on skirts
*Phosphat-coated to reduce micro-welding and pin galling
*Pin bores finished on CNC boring equipment
*High strength 9310, light weight nitrided steel wrist pins
*1.5mm plasma moly top rings, 1.5mm napier cast second rings
*3mm low tension oil rings
I like the tight fit.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
HDF Community Team
Joined: Jun 2006
Posts: 12,776
Likes: 2,607
From: san antonio
Select any piston you want but have cylinders bored and new pistons fitted to the piston manufacture's specs. Should be obvious from previous posts that purchasing a piston cylinder kit is a crap shoot. If you truly "like the tight fit" having the cylinders bored to fit the pistons is the way to go.
Last edited by djl; Oct 20, 2016 at 10:13 AM.