Oily plug

[rking1550]

Oily plug is the rear cylinder. Any thoughts as to what's going on ?
Motors a 120" 11.3 compression, t- man 662-2 cams & thumper heads .
I plan on getting a bore scope to take a look in the cylinder.

[Ohio HD]

Maybe intake valve seal ~ valve guide worn or damaged.

[rking1550]

Maybe intake valve seal ~ valve guide worn or damaged.

Not sure but I think there's only about 12-15k on the heads. T- man heads done about 6 years ago, but sat on the shelf for a season or two. But I guess anything's possible.

[Hossamania]

How many miles on the plug?

[rking1550]

How many miles on the plug?

1 season 3500 ish.   I put in new plugs, I'll check it after a couple hundred miles

[FSG]

what plugs ?

[rking1550]

what plugs ?

Harley SE 

[kd]

Here's what I would do.  Remove the breather and prop the throttle plate full open.  Do a compression check and a leak down test before going any further.  A wet rear cylinder may not show low compression but do it anyway. A leakdown may be similar when wet with oil but should make audible indications of a leak if it's bad. These 2 tests are important to determine state of the engine's constitution and if you start to disassemble it there's no going back and it's lost information.

Have a look for oil in the rear manifold runner, on the rear intake valve stem and bottom of the valve and guide.  If it's wet it could also be coming from the cylinder during cam overlap and may have spread over to the front manifold runner.  (That would be normal for that to happen.)

If you find oil in the cylinder with a bore scope along with wet manifold runners but no heavily scored cylinder walls, before you pull the head off try to check the valve seals with the head still on the barrels.  A Nub Tool will allow you to do this by just removing the top rocker box and rockers only.  If you don't have one or know someone to lend you one they are not all that expensive if your problem is a valve seal.  Goodson Tools is one place that sells them.  You will save a bundle in time and money for just the first use. You can remove the valve springs and inspect the valve springs, seals, and guides.  Have a set of seals on hand in case that's the problem.  If so, change them and reassemble.

Everything mentioned should be doable in about 4 hrs if it's only a seal and your compression etc. is even and good.  That's a far cry from removing the head and digging in if not needed.  Hopefully it's not broken or lined up rings. 

I have been exactly (same cylinder) where you are at with my 120 (same compression etc) and used the Nub Tool to rule out the "easy stuff" first.  Good luck in your findings and I hope it goes well.   

[les]

Are you using roller rockers?

[rking1550]

Are you using roller rockers?

Yes

[Hossamania]

Are the breather tubes run externally?

[rking1550]

Are the breather tubes run externally?

Yes, they are.

[rking1550]

Here's what I would do.  Remove the breather and prop the throttle plate full open.  Do a compression check and a leak down test before going any further.  A wet rear cylinder may not show low compression but do it anyway. A leakdown may be similar when wet with oil but should make audible indications of a leak if it's bad. These 2 tests are important to determine state of the engine's constitution and if you start to disassemble it there's no going back and it's lost information.

Have a look for oil in the rear manifold runner, on the rear intake valve stem and bottom of the valve and guide.  If it's wet it could also be coming from the cylinder during cam overlap and may have spread over to the front manifold runner.  (That would be normal for that to happen.)

If you find oil in the cylinder with a bore scope along with wet manifold runners but no heavily scored cylinder walls, before you pull the head off try to check the valve seals with the head still on the barrels.  A Nub Tool will allow you to do this by just removing the top rocker box and rockers only.  If you don't have one or know someone to lend you one they are not all that expensive if your problem is a valve seal.  Goodson Tools is one place that sells them.  You will save a bundle in time and money for just the first use. You can remove the valve springs and inspect the valve springs, seals, and guides.  Have a set of seals on hand in case that's the problem.  If so, change them and reassemble.

Everything mentioned should be doable in about 4 hrs if it's only a seal and your compression etc. is even and good.  That's a far cry from removing the head and digging in if not needed.  Hopefully it's not broken or lined up rings. 

I have been exactly (same cylinder) where you are at with my 120 (same compression etc) and used the Nub Tool to rule out the "easy stuff" first.  Good luck in your findings and I hope it goes well.   

What did your issue end up being?

[kd]

Rings were lined up

[rking1550]

Rings were lined up

Did you have lower compression with the rings lined up like that ?

[kd]

No.  This problem occurred on the dyno with a fresh engine with only heat cycles and 10 miles plus dyno time.  It was discovered as black exhaust smoke on heavy pulls about 2 hrs into the tuning.  The tuner (and myself) first thought we were seeing signs of a rich AFR.  He said it was where it should be and tried to clean it up but stopped when it started to get too lean and it still belched black smoke on a heavy throttle hit. We stopped tuning and did a compression test and leakdown.  When I opened the throttle blade for the cranking test I saw the oil pooled in the manifold. 

We did the CCP test and a leakdown and it tested 205 / 205 with less than 3 percent leakdown  .  We backed it out of the booth guessing a valve seal had slipped off. Things like that do happen..

Long story short ....... As I was about 2 hrs away from Goodson, I went there and bought the Nub Tool.  Back at the shop I pulled down the rear rockers and everything looked good.  The seals were changed anyway and it was put back together and back on the drum.  No change.  It went back onto the lift table and pulled the rear barrel.  The pic in my post is exactly how it looked when the barrel was slipped off.  A whisker hone and new rings and back together, problem solved.  I ran the info in an earlier thread with the cylinder autopsy etc but it's not important here.  My understanding is rings lining up is not common but usually happens on fresh rings and cylinder work.  Your's isn't fresh but who Knows    In the other thread, a couple of others chimed in and were experiencing the same issue so it does happen.  Rings "always" rotate.

[MikeL]

I just finished servicing my 2000rkc 124 11:1 S&S 640 cams, carb, and Kirby 110 stage 2 heads. My back spark plug had some oil residue also. 11k miles on the plugs. Engine vents external. There is some oil consumption I added 8 oz in 4k miles. Engine has 11k on it. It runs well no complaints about smoke or smell from people behind me.
I'm gonna run it and check the plugs in a couple hundred miles.

                                                                                                                                                                    MIKE 

[Tynker]

Out of round barrels will line up ring gap also.