Need help with tuning...
Road Warrior
Joined: Dec 2007
Posts: 1,286
Likes: 64
From: SoCal
Harley didn't start putting valve guide seals in the heads until late 1981 according to my manual. So they may or may not have seals, it depends upon who did the valve work or if the owner told them to put seals in or not.
The black wetness in the intake ports is not unusual and there will be some oil since there were no guide seals.
Oil on top of the piston however is not good unless you squirted some in there doing a compression test. Usually if the engine is burning oil badly the carbon buildup normally found all across the piston top will not be present around the edge of the piston next to the cylinder wall. Of course, it would smoke as well.
The black wetness in the intake ports is not unusual and there will be some oil since there were no guide seals.
Oil on top of the piston however is not good unless you squirted some in there doing a compression test. Usually if the engine is burning oil badly the carbon buildup normally found all across the piston top will not be present around the edge of the piston next to the cylinder wall. Of course, it would smoke as well.
Thread Starter
|
Intermediate
Joined: Jun 2011
Posts: 26
Likes: 0
From: Mechanicsville, VA
I did order valve seals for this year bike. If they didnt come on it in 1973, it will have them now.
I did find both of the exhaust valves were very sloppy in the guide, so Im replacing the guides on those too.
Question is, if the oil isnt coming from around the valve stem and guides, where is it coming from? The piston rings are new. I will check them before I put the heads back on just to be sure.
The top of the piston and inside the combustion chamber of the head was covered with oil sludge. If I had to guess the bike has only been run about 30 minutes to an hour total, between test rides and tuning.
Is there someway I'm getting too much oil pressure? Crank case pressure? Forcing oil into the combustion chamber??
I would hate to put it all back together and still have the same problem.
I did find both of the exhaust valves were very sloppy in the guide, so Im replacing the guides on those too.
Question is, if the oil isnt coming from around the valve stem and guides, where is it coming from? The piston rings are new. I will check them before I put the heads back on just to be sure.
The top of the piston and inside the combustion chamber of the head was covered with oil sludge. If I had to guess the bike has only been run about 30 minutes to an hour total, between test rides and tuning.
Is there someway I'm getting too much oil pressure? Crank case pressure? Forcing oil into the combustion chamber??
I would hate to put it all back together and still have the same problem.
Tourer
Joined: Jun 2008
Posts: 306
Likes: 7
From: Somewhere, PA
"Too Much" oil pressure usually isn't a problem on these old motors, as they rely more on volume than on pressure. Usually the oil is entering through the guides or by the rings. Even if the rings are new, if they weren't gapped or spaced correctly they can be the cause of issues. My guess is still on the valves, especially if they were sloppy, but we'll all tell you that it's much easier to diagnose with our hands on the motor rather than via text on a forum. Good luck, keep posting updates and we'll try to help where we can...
Thread Starter
|
Intermediate
Joined: Jun 2011
Posts: 26
Likes: 0
From: Mechanicsville, VA
"Too Much" oil pressure usually isn't a problem on these old motors, as they rely more on volume than on pressure. Usually the oil is entering through the guides or by the rings. Even if the rings are new, if they weren't gapped or spaced correctly they can be the cause of issues. My guess is still on the valves, especially if they were sloppy, but we'll all tell you that it's much easier to diagnose with our hands on the motor rather than via text on a forum. Good luck, keep posting updates and we'll try to help where we can...
I understand.
I appreciate any and all help given.
I will definitely keep the updates coming.
Thread Starter
|
Intermediate
Joined: Jun 2011
Posts: 26
Likes: 0
From: Mechanicsville, VA
New problem... Pistons are stock size but the cylinders have been bored out .020
Now I really feel like an idiot. I was told by the previous owner they were the right ones and it has "20" on the top of the pistons. So I assumed...
Ordering new ones now..............
Now I really feel like an idiot. I was told by the previous owner they were the right ones and it has "20" on the top of the pistons. So I assumed...
Ordering new ones now..............
Thread Starter
|
Intermediate
Joined: Jun 2011
Posts: 26
Likes: 0
From: Mechanicsville, VA
I can do all that with what I have here in my shop.
I really feel dumb for not checking the tolerances before I put the motor together.
Im embarassed to say Im a machinist by trade and should have double checked.
I was anxious to get it back together and overlooked a few things.
Wont happen again......
I really feel dumb for not checking the tolerances before I put the motor together.
Im embarassed to say Im a machinist by trade and should have double checked.
I was anxious to get it back together and overlooked a few things.
Wont happen again......
Tourer
Joined: Jun 2008
Posts: 306
Likes: 7
From: Somewhere, PA
Waitaminute...if the top of the pistons read .020 then they are 20 thousandths oversized. Have you, or a wrench you trust, measured the skirt of the piston with a mike and then compared it to the cylinder wall width (again, with a mike) to see the difference? That's the easiest way to tell if you're within specs. If you don't have the tools to do so, I would suggest that you have a local wrench do it for you before you start ordering parts...
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
6 Weirdest Harley-Davidsons Ever Sold to the Public
Verdad Gallardo
7 Times Harley-Davidson Chucked Tradition Out the Window
Verdad Gallardo
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
Thread Starter
|
Intermediate
Joined: Jun 2011
Posts: 26
Likes: 0
From: Mechanicsville, VA
I used an inside mic to measure the bore of the cylinder. It was 3.457
The piston is 3.425
Stock bore is 3.438
The top of the piston is stamped 020
I have no idea why the piston is .013 smaller than stock. It actually looks new.
I called the Harley shop and told him the bore and he ordered .020 over sized pistons
I will still need to hone the cylinders out another thousandth or two
Like I said, I am a machinist and have plenty of tools, was just anxious to get it back together.
This is pretty embarrasing, but maybe someone can learn from my mistake.
The piston is 3.425
Stock bore is 3.438
The top of the piston is stamped 020
I have no idea why the piston is .013 smaller than stock. It actually looks new.
I called the Harley shop and told him the bore and he ordered .020 over sized pistons
I will still need to hone the cylinders out another thousandth or two
Like I said, I am a machinist and have plenty of tools, was just anxious to get it back together.
This is pretty embarrasing, but maybe someone can learn from my mistake.
Stellar HDF Member
Joined: Jun 2011
Posts: 2,158
Likes: 35
From: Gulf Breeze, FL
At what point on that brand of piston does Harley recommend measuring? I know Wiseco's measure 90 degrees from the wrist pin at the base of the piston...others may vary.
Last edited by rickss69; Jun 21, 2011 at 12:03 AM.