Piston/ cylinder scoring
Road Captain
Joined: Jan 2014
Posts: 566
Likes: 70
From: The Redneck Riviera
Nope, not normal at all,,, looks to be improper boring / piston / cylinder fitment... A bad Tune could also be a contributing factor...
Needs to be addressed (at the very least, if you're lucky) with new Pistons, Rings, & Cylinders properly fitted...
Guessing that they are off of your 107??
Pull the Crank Position Sensor,,, if any metal on it, you can start shopping for that 124 you've been wanting... Also examine the drain plug magnet, and cut the oil filter open and look inside...
Needs to be addressed (at the very least, if you're lucky) with new Pistons, Rings, & Cylinders properly fitted...
Guessing that they are off of your 107??
Pull the Crank Position Sensor,,, if any metal on it, you can start shopping for that 124 you've been wanting... Also examine the drain plug magnet, and cut the oil filter open and look inside...
Thread Starter
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Cruiser
Joined: Jan 2016
Posts: 160
Likes: 14
From: North of Denver
Could pinging, pre-ignition or detonation cause this kind of side thrust (front/ back) and resultant wear to occur on the intake side of both pistons?
Last edited by GibsonSG; Mar 7, 2017 at 10:35 AM.
Road Master
Joined: Dec 2013
Posts: 1,238
Likes: 96
From: fort walton beach
I am not 100% sure but most cp pistons are 2618 forged aluminum and they require a lot more space than cast and hyper pistons. Depending on who machined your hugs but they may not have put enough piston to wall clearance
HDF Community Team
Joined: Jun 2006
Posts: 12,763
Likes: 2,597
From: san antonio
I think you mean "pre-ignition" but the answer is no. Have the cylinders measured in torque plates and measure piston; I am betting you will find the problem. Plenty of YouTube videos and other "how to" articles on the internet showing where to measure.
Thread Starter
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Cruiser
Joined: Jan 2016
Posts: 160
Likes: 14
From: North of Denver
So the question is...will this get worse or is the scoring due to a clearance issue brought about by extremes and only a rare occurrence that may be eliminated by a better tune?
4 options come to mind now:
#1: Do nothing and hope the scoring cleared the variance and doesn't significantly affect compression or oil consumption, focus on a better tune.
The pistons appear to be the softer material and taken the brunt of the damages. I guess a compression test would help understand the extent of any damage done but doesn't give any indication of future risk.
If I get to the point of pulling the jugs and having them in torque plates to measure concentricity...then I have what I see as 3 remaining options:
#2: Bore/ hone cylinders to clean up the scoring and bring them to true:
Cost consideration, about $600 for boring and new pistons & rings
Dis-advantage: downtime and waiting on the return of my only set of jugs
#3: A 110CI setup: either a HD or FM kit that includes cylinders and pistons/rings
Cost consideration: about $1000 for a 'drop-in' kit
Advantage: new components, lessened downtime
Dis-advantage: estimated HP may put the crank as the next weakest link, the same $1000 toward a 110 could be put toward the top end kit of a 124...
#4: 124" short block, plus exhaust, clutch & cams
Cost consideration: hefty, especially for a 2015 with only 6500 miles
Advantage: S&S crank, Timken conversion, 124"...and this is ultimately where I wanna end up
Disadvantages: expense, shipping, downtime
4 options come to mind now:
#1: Do nothing and hope the scoring cleared the variance and doesn't significantly affect compression or oil consumption, focus on a better tune.
The pistons appear to be the softer material and taken the brunt of the damages. I guess a compression test would help understand the extent of any damage done but doesn't give any indication of future risk.
If I get to the point of pulling the jugs and having them in torque plates to measure concentricity...then I have what I see as 3 remaining options:
#2: Bore/ hone cylinders to clean up the scoring and bring them to true:
Cost consideration, about $600 for boring and new pistons & rings
Dis-advantage: downtime and waiting on the return of my only set of jugs
#3: A 110CI setup: either a HD or FM kit that includes cylinders and pistons/rings
Cost consideration: about $1000 for a 'drop-in' kit
Advantage: new components, lessened downtime
Dis-advantage: estimated HP may put the crank as the next weakest link, the same $1000 toward a 110 could be put toward the top end kit of a 124...
#4: 124" short block, plus exhaust, clutch & cams
Cost consideration: hefty, especially for a 2015 with only 6500 miles
Advantage: S&S crank, Timken conversion, 124"...and this is ultimately where I wanna end up
Disadvantages: expense, shipping, downtime
Last edited by GibsonSG; Mar 7, 2017 at 11:09 AM.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,830
Likes: 7,968
From: poway
What ever you do. Don't use those pistons/rings.. It looks like it was either setup tight, possibly not cleaned properly or possibly loss of oiling. If it was heat related there would be more scoring at the top of the skirt.. It looks more like it started sticking at the bottom. You might get away with running a fixed hone through to clean up the cylinder and make it round, especially if the cylinders were tight to start with or if you can live with a little piston rattle.
One thing to note, detonation can cause piston seizure. It blows the boundary layer away and transfers combustion temps to chamber and piston. It not the case in this one tho.
One thing to note, detonation can cause piston seizure. It blows the boundary layer away and transfers combustion temps to chamber and piston. It not the case in this one tho.
HDF Community Team
Joined: Jun 2006
Posts: 12,763
Likes: 2,597
From: san antonio
Forget about Option #1; non starter. As for the others, dealer's choice. However, I would say that Option #2 to get the bike back on the road to ride while saving for Option #4 would be my path. You can work out a deal with Scott/Hillside or Kirby/VeeTwin (both forum sponsors) that will minimize down time. I am pretty sure they will work with customers on an exchange basis. The customer pays a core charge for the cylinders (or heads), they do the machine work, buy and fit the pistons and return to the customer; no down time for the customer. The core charge to be refunded to the customer when they receive the cylinders in good serviceable condition.
Banned
Joined: Jan 2017
Posts: 894
Likes: 25
From: Jacksonville FL
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Seasoned HDF Member
Joined: Dec 2005
Posts: 19,830
Likes: 7,968
From: poway
You really want something better than a caliper to measure the piston. Micrometer can be had pretty cheep. Some of the Chinese ones aren't too bad. Not as good as a Starrett or Mitotoyo tho. Snap gauges will get you to within a quarter thou on the bore.
Road Captain
Joined: Jan 2014
Posts: 566
Likes: 70
From: The Redneck Riviera
So the question is...will this get worse or is the scoring due to a clearance issue brought about by extremes and only a rare occurrence that may be eliminated by a better tune?
4 options come to mind now:
#1: Do nothing and hope the scoring cleared the variance and doesn't significantly affect compression or oil consumption, focus on a better tune.
The pistons appear to be the softer material and taken the brunt of the damages. I guess a compression test would help understand the extent of any damage done but doesn't give any indication of future risk.
If I get to the point of pulling the jugs and having them in torque plates to measure concentricity...then I have what I see as 3 remaining options:
#2: Bore/ hone cylinders to clean up the scoring and bring them to true:
Cost consideration, about $600 for boring and new pistons & rings
Dis-advantage: downtime and waiting on the return of my only set of jugs
#3: A 110CI setup: either a HD or FM kit that includes cylinders and pistons/rings
Cost consideration: about $1000 for a 'drop-in' kit
Advantage: new components, lessened downtime
Dis-advantage: estimated HP may put the crank as the next weakest link, the same $1000 toward a 110 could be put toward the top end kit of a 124...
#4: 124" short block, plus exhaust, clutch & cams
Cost consideration: hefty, especially for a 2015 with only 6500 miles
Advantage: S&S crank, Timken conversion, 124"...and this is ultimately where I wanna end up
Disadvantages: expense, shipping, downtime
4 options come to mind now:
#1: Do nothing and hope the scoring cleared the variance and doesn't significantly affect compression or oil consumption, focus on a better tune.
The pistons appear to be the softer material and taken the brunt of the damages. I guess a compression test would help understand the extent of any damage done but doesn't give any indication of future risk.
If I get to the point of pulling the jugs and having them in torque plates to measure concentricity...then I have what I see as 3 remaining options:
#2: Bore/ hone cylinders to clean up the scoring and bring them to true:
Cost consideration, about $600 for boring and new pistons & rings
Dis-advantage: downtime and waiting on the return of my only set of jugs
#3: A 110CI setup: either a HD or FM kit that includes cylinders and pistons/rings
Cost consideration: about $1000 for a 'drop-in' kit
Advantage: new components, lessened downtime
Dis-advantage: estimated HP may put the crank as the next weakest link, the same $1000 toward a 110 could be put toward the top end kit of a 124...
#4: 124" short block, plus exhaust, clutch & cams
Cost consideration: hefty, especially for a 2015 with only 6500 miles
Advantage: S&S crank, Timken conversion, 124"...and this is ultimately where I wanna end up
Disadvantages: expense, shipping, downtime