Twin cam base gasket leak - Harley Forum

weig0047 · #1 06-26-2009, 10:56 PM

Ok, so I've been lurking around for a few days now, trying to soak up as much info as I can, but I haven't seen anyone with the problem I'm having. I know there are some folks here with some pretty serious HD knowledge so I thought I throw it out there.

I have a 99 FLHTC with 80,000 miles that has developed a base gasket leak on the back side of the rear cylinder (film of oil weep where the cylinder meets the case about 120 deg around). Has anyone seen this problem before?

About my girl: S&S super E, what look like S&S SPO mufflers (I cannot tell as they are completely unmarked, they have very limited baffles though), stock B (EFI) cams, adjustable push rods, new lifters 3,700 mi ago, jetted real rich (AFR 12.8 at idle and around 8 at 4500 rpm). She also seems to have an excessive amount of tick from the rockers from 2300-2800 rpm, not a huge concern as most of my riding is done at 3000+.

I am a little nervous about opening up the top end though. I've read through Fxt 03's post on top end rebuild and it seemed very time consuming. Summers here are short and I won't do well if I can't ride for a couple of weeks.

Am I correct in assuming this is a base gasket leak?

If this is correct is a top end overhaul in order?

How much time should I figure for my first top end?

The stealer keeps telling me that Evo's leaked there and not the TCs, and that I should be good to 100,000 on my top end...

Any help is greatly appreciated.

frisco-rigid · #2 06-27-2009, 12:42 AM

Hi 0047

I appreciate your concern but a wee "....film of oil weep..........." is a wee prob and unless it gets waaay worse just live with it and do your repair work in the Off Riding months..

In the mean-time I would advise you to trim up that Super E cuz running that fat is a real power/perf burgler, not to mention mileage and the heat associated with a super fat Mix..
A very Fat mix burns slowly (do not confuse with slower burning Hi-Octane Gas) and doesn't provide normal power making the motor work harder to do anything,, much less tote a Pick-nic basket and a Big girl Up a hill..

How did you get those numbers--- off an Emmisions or Dyno sniffer or what.???
That 8 - 1 seems almost Un-believable,, I'm surprised it even moves..

I'm guessing the Intermediate & the Main are both tooo big..
With an E you're fully into the Main at 4500 along with the other 2 systems,, idle and Inter..

Just something to consider..

weig0047 · #3 06-27-2009, 01:44 AM

Frisco, nice to er... meet you. Thanks for the input, I was hoping that would be more-a-less the answer.

Those numbers came off an exhaust gas analyzer my old man uses to set emissions on forklifts. I haven't checked the intermediate, but the fella that had it before me stuck an .074 main in... Jets are on their way right now(both main & Int.). Plugs read: porcelain white to gray, base ring shows rich. Back fires on decel like crazy. I've never ridden it jetted any leaner, so i''m hoping for good things...

Any thoughts on whether it would increase the leak/stress the valve train if I stuck a .510 C in?

frisco-rigid · #4 06-27-2009, 03:31 AM

Hi 0047

I just read a wee bit about the .510 C,, Part Number: 11326826..
States it's for stock springs and chain,,, etc. so I bet it'll be just fine and prob will not stress anything, especially the leak/weep..
Bolo on Wrightturn --- Ace..

OK the A/F..
If the porcelain is light-colored as you say then it's NOT as rich as you think..
I am going to guess that the Analyzer used was faulty or mis-read or maybe meant for Propane or something..

Did you get that color after a high-spd shut-down..
You can go off the base ring, I know alota folk do,, I read the porcelain and electrodes and when I double check with a Dyno sniffer I'm right-on--- your call.. I look for lite-med tan or med gray,, that usually reads about 13.5 ish in my motors..

A .74 Main should Not be over-rich for your motor,, heck I was expecting to hear that there's a .88 or .96 Main in there..

My guess for that motor will be a .295 - .31 Inter and .74 main sounds very reasonable..

A great way for you to know for sure is to run a High-spd then a Low-spd plug test.. Do you know how.?
I'll describe if you like..

The de-cel pop-back is generally a lean prob and can usually be stopped or lessened with a fatter Inter (with the E) or a wee rich setting of the Idle A/F screw on top.. If the plug color you describe was after idling that could be the prob..
Using a 1-step up Inter (over correct size) is Not the best solution..
What exhaust are you running.? A crappy exhaust system can enable de-cel pop..
Just for grins n giggles,, have you sprayed for intake leaks.? And hows the timing----- timing must be correct before final jetting..

I ran S&S's for over 30 years but it won't take long for you to realize I have No respect for the E..
If you want to spend some money on perf get a 45 Mikuni,, they're like adding Inches..

aceharleywrench · #5 06-27-2009, 07:00 AM

Frisco,once again,you've left very little for me to add.I would check the rear pipe for cracks (very common) as this is known to cause decel pop & may be the "lifter noise" 0047 mentioned.Use the S&S for a smelly paper weight & bolt on a Mikuni.

weig0047 · #6 06-27-2009, 02:37 PM

Frisco, That plug reading was at idle. I've not done the high speed/low spd plug readings, but I have read up on it and am on my way out to do it right now. As for the mufflers I wish I could tell you a little more about them, but I'm at a loss. I've had them off and gone over them several times, but cannot find any manufacturers markings of any kind. There is a bit of a restrictor plate in them, but behind it (towards the engine) there is nothing only some corrugations ir bumps on the walls of the pipe.

Ace, as far as the rear pipe I'm assuming you mean the Y pipe on the rear cylinder? It was supposedly replaced about 20,000 mi ago shortly before I got the bike, due to corrosion. Could it be cracked already? It is currently wrapped so a thorough inspection will have to wait of at least a little while.

I'll let you know the results of the plug tests tomorrow.

frisco-rigid · #7 06-27-2009, 07:54 PM

0047

You are my fav kinda Question-er..

Your inquiry comes with Info, then you come-back with more Info, then you are willing to inspect, look over stuff, report back & answer our questions,,,, jeeeeze,,,, sooo much better than ----"my motor won't run,, what's the problem" <<<< only a wee bit of exaggeration..

You make it easy for us to assist you,,, sooooo cool..!
Yeah Baby..

Make sure you "close down" the Accell pump when doing the plug tests..
If done already and you didn't,, it'll still be close..

weig0047 · #8 06-28-2009, 05:56 PM

How could you give me answer without any info man?

Ok, did the plug test: @ 4500 rpm front plug tan on tip white at base of porcelain, rear plug white with very little tan speckling. @ 2500 bascially the same except it looks learner, the color is lighter and the rear plug has even more white. (accel pump was on, didn't even think to turn it off)

I guess the numbers I had are totally garbage...

The only plugs I have experience reading are in two strokes, where I shot for a nice toasted marshmallow color. Should I be looking for about the same in a twin cam?

Also, one thing to note. I just came off a 250 mile run averaging about 80-85 temp 75 deg, shut her down and came back with the carb cleaner to check for intake leaks. When I started her up I had a definite knock and a slow idle. Symptoms of overheating correct? Would richening it up take care of this/should I be concerned? No knock was apparent when riding.

Thanks for all the input man, its greatly appreciated.

frisco-rigid · #9 06-28-2009, 06:22 PM

Hey 0047

Ha,,, if you were a wee lean even with the pump on then it's definately lean..
You see, the S&S pump can be very touchy and slightly dribble in gas even while just cruising,, they are dreadful.. The Super B is Fantas. the E is crap..

Ok anyway,, I would go up one size in the inter and one with the main also..
Then test again..
Do you know what size the Inter is.?
Another thing---- I would adjust the idle A/F to the rich end of the dial, in my experience S&S's like that..

Now here's a concern..
With the E's & G's the main comes in at about 2500 +-, kinda low actually..
So, at 2500 you mighta been transitioning in & out between the main and Inter..
Even so I believe 1 step up with both is advisable..

Most definately be concerned about knock and un-predictable idling..
Did you get that knock After you shot the spray while checking for leaks..?
Did you get Any diff RPM's while spraying..? If yes, first double check and spray again and if leaking you must fix that prob..
If you did not get diff Rpm while spraying and that knock and slow idle was just "there",,, then it very well coulda been from heat after runnin lean & Hot..

Again--- is your timing confirmed Correct.? Timing must be final before final A/F jetting..
If yes,,, then after you jet properly,,, the heat will subside somewhat and perf will be better..

Oh yeah--- those numbers were dead wrong.. And something else,, while the bowl is off when changing the Inter, check the float level, make it right..

I'll check back in a wee bit..

weig0047 · #10 06-28-2009, 09:10 PM

Frisco,

The knock was there on start up. As for the timing, its still running with the stock box. So no adjustment correct?

Probably not gonna get a chance to dig into it tonight. Its a bummer the only time of year you can ride a bike here is the same time you have to ride a lawn mower. I'll let you know tomorrow what I find out.

Guess it's time to start lookin for ignitions, I'd better hit the books.