S&S 124 LC

[conmag]

 About 4 years ago I put an S&S 124LC in my bike, now at 14k miles it is using about a quart of oil every 800 miles, Oil seems to get black real fast, inside intake gets dirty fast, and it has HPI external breathers, motor is quite and runs good, going in next week and take the top end down, motor is well taken care of, and not abused, what does everyone think we will find wrong?

[Ohio HD]

I would recommend two things before you take it apart. A compression test and a leak down test. The leakdown test will point you where to look first.

[conmag]

I was thinking about that, but in the long run it will need to be tore down I feel, so than I pay someone to run the tests, and than tare it down, I will talk to the people doing the work next week.

[jmorton10]

Do the tests yourself, it's easy to do.

I can loan you the testers if you want ??

John

[wfolarry]

Rings are shot.

[nibroc]

Rings are shot.

....>AGREE....

[Don D]

The cylinders need to be plated and checked before just re-ringing and I agree the rings are shot.

[Admiral Akbar]

Rings are shot.

From too much timing and too much fuel? 

[Don D]

Could also just be bad hone to begin with and / or unstable cylinders that are distorted. I have measured many that are not showing problems in the tenths, multiple thousandths top to bottom and across both axes.

[Buglet]

   Had a couple that had bad valve seals. They would slide down the valve stem with no restriction.

[conmag]

The Dyno sheet, don't look like to much fuel

[kd]

I would recommend two things before you take it apart. A compression test and a leak down test. The leakdown test will point you where to look first.

I agree.  The rings may have not seated or one cylinder has lined up the gaps and stalled there.  You want to trouble shoot the source before disassembling or it will be a crap shoot.

[Don D]

The rings stop turning when the cylinders are out of round, just on further level to the root cause.

[conmag]

Probably tear it down bore it, thinking about sending heads to Than.

[kd]

The rings stop turning when the cylinders are out of round, just on further level to the root cause.

I had that exact thing happen on a rear cylinder that I measured (when blueprinting the engine) to be within spec but clearly deviated on the right side to be .0005 out for the full length.  That's exactly where the rings stalled during break in on the dyno. All of them including the oil scraper rings were dead even as though it was intended. I have a pic.

[wfolarry]

Rings are shot.

From too much timing and too much fuel?

Yes

Here's a question for you guys. Does anybody know why they recommend the ring gaps staggered the way they do? It was in an automotive repair manual I have that's 50 years old so the answer is even older than that. 

[choseneasy]

I was told to start the gap on the compression ring to the intake valve so it gets a shot of cool air instead of hot exhaust gases on start up.
  Not going to look but I thought the factory manual supports that theory?

[kd]

It is to prevent crankcase oil from contaminating the combustion. 

Clearly that's how I detected my rings were lined up when on the dyno.  It was belching black smoke like an over fueling diesel.  The AFR's were spot on and leaning it out (within reason) made no change.  Deciding to do a compression check while on the drum, while holding the throttle valve open with a screwdriver, a "heavy" oil film was seen coming from the rear intake runner. Long story short, the pic of the rings in my previous post was taken seconds after the barrel was slid off and obvious from a distance.  What I had was a hot oil jet injecting into the combustion on the downstroke of intake.  The resulting downstroke crankcase pressure assisted it because the Harley crankcase capacity is so small the pumping effect signal is greater.

[Don D]

I know the answer but will let others try their hand at it.

Why do the rings stop turning, is that an issue?
What if ring end gaps are high side large of the spec? Will the motor have a lot of blow-by as a result?
Can "rings are shot" be quantified, yes, the growth in ring end gaps plus appearance.

[kd]

I know the answer but will let others try their hand at it.

Why do the rings stop turning, is that an issue?
What if ring end gaps are high side large of the spec? Will the motor have a lot of blow-by as a result?
Can "rings are shot" be quantified, yes, the growth in ring end gaps plus appearance.

My previous response is a personal experience event.  The OP is experiencing severe oil consumption and it may be relevant.

There of course are other reasons and resulting negatives of rings lining up.  Another is rings can lose solid contact with the cylinder and piston ring groove surfaces due to loss of the force created when the high pressure combustion gasses fail to travel behind them as they will have to when the rings are staggered.  That will cause excessive blow-by, excessive crankcase pressure and usually oil consumption.  It doesn't necessarily effect CCP if the gaps are good but may show up in a leak-down test.  Aligned rings will also allow the rings to flutter somewhat as the piston changes direction because the cylinder pressure that forces them against the cylinder wall and piston surfaces is too weak to control them.  Fluttering rings can negatively effect cylinder, ring, and piston ring groove wear.

[Ohio HD]

Rings are shot.

From too much timing and too much fuel?

Yes

Here's a question for you guys. Does anybody know why they recommend the ring gaps staggered the way they do? It was in an automotive repair manual I have that's 50 years old so the answer is even older than that. 

Larry, my memory from trade school was to minimize the effect of the wear from the ring gap on the cylinder wall. By staggering it helps to prevent localizing the wear. Also I was taught that the rings do rotate by intent and help to prevent that same localized wear.

[Die Hard]

I also had an S&S 124 LC in my Street Glide with 14,000 miles on it. I have since turned it into a HC as they come from S&S with the addition of head work from Jim at MegaFlo.

There are two things that engine does not like. Excessive heat from riding in stop and go traffic on a hot day which can be damaging to top end parts and running the oil level too high where there is not enough air space for it to breath. I added a 1.5quart + oil pan and run the oil level a full quart below the factory specs. Synthetic oil also helps to keep the head temps down. My oil usage was a quart to every thousand miles, now the oil use is minimal.

[conmag]

Ok the motor apart, but it's odd there is rust in both cylinders, one worst than the other, and it's on the middle of the stroke, cylinders are at the machine shop now,they will check to see if they are straight, I'm going to order .010 over pistons. Anybody ever seen this before, bike is always stored in a heated garage, during the winter.

[Barrett]

It sounds like condensation. Cranking them up without letting them get hot enough to burn it off will do it.

[kd]

The engine is sitting there with valves open breathing in the air.  Do you live in a humid climate?

[Don D]

Common. From humidity. Consider CRC Engine Stor fog before putting the bike up in the winter.

[Barrett]

There's a 93 FXR with 9,365 miles on the local C/L.
I was wondering how it would look inside sitting so long.
It sure is a garage Queen.
I ride year long being in Fl. but limit my riding to night in the summer.
Less traffic and heat.

[turboprop]

FXRs are like wooden boats or victorian houses,  they require a lot of maintenance. Aside from the two years of CVO models, the last FXR made came off the line almost thirty years ago. Even the nice looking ones often require a total tear down and rebuild.