When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
Ok, I will definitely get an inside micrometer to measure when I check these rings, this new kit is a se kit from suburban speed which is a Harley shop that does the king of the baggers bikes, new cylinders with fresh bore and they say the rings are gapped and just need to be checked, when I did them last time I just took revolutions word on the 3.93 bore size, but didn’t account for the nikasil coating in the bore, that coating breaks down fast as you can see in the cylinders, I gapped rings based on the size listed on the bore and may have been a little tight, thank you again
If you are using moly filled rings you found your problem. Get the rings from either wiseco or RP. Wiseco rings are SS and softer. Moly and nikasil don't mix.
+1 mr.max
also, final cross hatch is also dependent upon ring/slug types.
seen tooooo many use a rough cut and file the rings down before break in is even finished going from a 3% to 20%+ loss on leak down.
when dealing with chrome stuff, detail is important, sometimes better to extend break in than a quick seat. sometimes it can take 1000's of miles. an ole hack was to use the CORRECT bon amie in the oil to help seat in. even then, care is forthcoming!!!
The first post asks where does all the carbon come from.......
your pictures do NOT show any kind of excess carbon on the piston tops,,,,most every hd ends up like that, not abnormal. if that is your concern, the only things you can do to really help are make sure your engine breather lines are vented to atmosphere, not back into the intake, make sure you've got a good tune in place, use good fuel and mybe investigate some sort of thermal coating for the piston tops, but it's still gonna look like it in the end.
m
Now near the end of engine life, they will once the rings loose control of lubrication do to worn pistons, cylinders and too wide a ring groove in piston.
And that takes a lot of miles, or adbuse, or especially a rich aftermarket tuner that basically turns a long life FI motor into a shorter life motor like a modified carburetors did.
Gasoline is a lousy lubrication.
The little bit of oil mist that enters the actual intake is drawn in(actually push in by atmosphere air pressure).
It's brought in as a gas air and a small amount of oil vapor mixture in the form of a gas as the piston goes to the bottom of the cylinder.
It if anything adds a extremely small amount of cylinder lubrication.
Actually liquid oil you see in air box is what accumulated in the passage ways over time and runs down.
You don't even see oil on the front of the butterfly. Now if you hold it open, and look back in there , you see fuel carbon left in intake ever time you shut it down with a sequential FI system.
The carbon oil deposits in the first poster picture are from a total loss of ring seal and oil control coating the cylinders and running over the edge of the piston.
Last edited by Jackie Paper; Jan 13, 2025 at 08:11 PM.
Now near the end of engine life, they will once the rings loose control of lubrication do to worn pistons, cylinders and too wide a ring groove in piston.
And that takes a lot of miles, or adbuse, or especially a rich aftermarket tuner that basically turns a long life FI motor into a shorter life motor like a modified carburetors did.
Gasoline is a lousy lubrication.
The little bit of oil mist that enters the actual intake is drawn in(actually push in by atmosphere air pressure).
It's brought in as a gas air and a small amount of oil vapor mixture in the form of a gas as the piston goes to the bottom of the cylinder.
It if anything adds a extremely small amount of cylinder lubrication.
Actually liquid oil you see in air box is what accumulated in the passage ways over time and runs down.
You don't even see oil on the front of the butterfly. Now if you hold it open, and look back in there , you see fuel carbon left in intake ever time you shut it down with a sequential FI system.
The carbon oil deposits in the first poster picture are from a total loss of ring seal and oil control coating the cylinders and running over the edge of the piston.
Here's a similar pic of a RP 4 1/4 bore nikasil cylinder on my 131. It was caused by using CP pistons that had moly filled rings.. These cylinders had a slightly different surface finish on them and less miles. RevPerf later changed over to Wiseco with SS top ring which this motor is using today.. Add: Cylinders were honed slightly with a ball hone..
Last edited by Max Headflow; Jan 14, 2025 at 08:51 AM.
on efi, when you kill the ign, the injectors quit firing so fuel residue would be nil unlike a carb. it is this residue that leads to intake fouling, reason why top tier fuel was invented.
as far as venting to atmosphere the c/c vapor, a BIG wives tale!!!!
IF your machine in in order, that vapor causes NIL issues. BUT if your machine is over taxing the really poor design system then issues will arise. there are billions upon billions of machines that prove that theory wrong.
hd needs a lesson from rice and not the lowest possible cost savings venture. that vapor is mostly water and if the coalescer chamber and umbrella (another poor choice by hd) are in order, once again no issues. i changed my system up and have nary a drop of oil in the cleaner and i am NO sunday school rider. the biggest issue with the system is where they vent to, a LOW FLOW area. what happens when you send a higher pressure through an orifice, it will lower in pressure and particulate matter drops out. if you route this to a high flow area, it get swept away and eventually get burned.
wear out an hd, sure but with proper maintenance it will be a long time. i had 179,000 miles on a 1974 xlch and running like a scalded dog, but due to frame restoration and bird in hand dropped in an S&S flywheel and upped the ponies with 10:1 slugs and Y cams.
you maybe right about one thing, upper cyl lube since the ch did not use stem seals, so it used oil right out of the crate.
on efi, when you kill the ign, the injectors quit firing so fuel residue would be nil unlike a carb. it is this residue that leads to intake fouling, reason why top tier fuel was invented.
as far as venting to atmosphere the c/c vapor, a BIG wives tale!!!!
IF your machine in in order, that vapor causes NIL issues. BUT if your machine is over taxing the really poor design system then issues will arise. there are billions upon billions of machines that prove that theory wrong.
hd needs a lesson from rice and not the lowest possible cost savings venture. that vapor is mostly water and if the coalescer chamber and umbrella (another poor choice by hd) are in order, once again no issues. i changed my system up and have nary a drop of oil in the cleaner and i am NO sunday school rider. the biggest issue with the system is where they vent to, a LOW FLOW area. what happens when you send a higher pressure through an orifice, it will lower in pressure and particulate matter drops out. if you route this to a high flow area, it get swept away and eventually get burned.
wear out an hd, sure but with proper maintenance it will be a long time. i had 179,000 miles on a 1974 xlch and running like a scalded dog, but due to frame restoration and bird in hand dropped in an S&S flywheel and upped the ponies with 10:1 slugs and Y cams.
you maybe right about one thing, upper cyl lube since the ch did not use stem seals, so it used oil right out of the crate.
Me thinks you got me cornfused with Paper. Look at my response..
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.
Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Slideshow: A standard cruiser becomes an intricate metal canvas in the hands of a Swiss custom house known for pushing Harley-Davidson platforms far beyond their factory brief.
Slideshow: Harley-Davidson's challenges aren't abstract; they show up in dropping shipments, shrinking dealer traffic, and strategic decisions that aren't yet translating into growth.
We did...
