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Folks, I'm disassembling both jugs on my '93 Ultra Classic to finally take care of the oil leaks at the cylinder bases. After taking off the exhaust and intake manifold, I took the following pictures of the backside of each valve.
Seems to be thick carbon deposits on both intake valves (Figure 1 and 3). Fuel too rich?
The front exhaust looks pretty good (Figure 2), but the rear exhaust (Figure 4) appears to have carbon deposits it.
Care to offer a diagnoses? New valve guides and seals?
Thanks!
-Dave
Figure 1 - Front Intake Figure 2 - Front Exhaust Figure 3 - Rear Intake Figure 4 - Rear Exhaust
Don't see any issues with guides. Wouldn't hurt to disassemble, clean and lap... Reroute your breather to atmosphere..
Now comes the while the heads are off I would shave them a little and go with a Cometic gasket set @.030" hg. A small bump in compression goes a long way with cam selections...
As YD stated a little more info would be appreciated...
Last edited by 98hotrodfatboy; Dec 10, 2019 at 06:03 AM.
Don't see any issues with guides. Wouldn't hurt to disassemble, clean and lap... Reroute your breather to atmosphere..
Now comes the while the heads are off I would shave them a little and go with a Cometic gasket set @.030" hg. A small bump in compression goes a long way with cam selections...
As YD stated a little more info would be appreciated...
The above is good advice...and have the base of each cylinder machined flat if you plan on a rebore or is this just a gasket swap? I highly recommend you give it a good once over on the top end, since it's already apart, and if you live in an area where your bike is down for winter hibernation. How many miles?
Lifters and cam/cam bearing also...let the snowball start getting bigger...YD
While the cylinders are off, have your machinist true the lower mating surface, this will go a long way toward preventing any future base gasket leaks.
Don't see any issues with guides. Wouldn't hurt to disassemble, clean and lap... Reroute your breather to atmosphere..
Now comes the while the heads are off I would shave them a little and go with a Cometic gasket set @.030" hg. A small bump in compression goes a long way with cam selections...
As YD stated a little more info would be appreciated...
All Good But... No Way I "lap" any valve... Either do it right...ie touch up the valve and seat, or Run it.. I'm sure the Seating surfaces are plenty Wide right now...
If the Head side of the valve stems is not Spotless clean [blasted?] more damage can be done dragging the stem thru the guide than you will ever be curing if not all done correctly... again... leave 'em in place or go "all the way"
Originally Posted by Dan89FLSTC
While the cylinders are off, have your machinist true the lower mating surface, this will go a long way toward preventing any future base gasket leaks.
Truly Flat, and gain a bit of compression ...as 98HRFB states...
I would Not miss this opportunity to replace Cam bearing, and certainly assess how many miles are on the Lifters!!!
Last edited by Racepres; Dec 10, 2019 at 08:56 AM.
Pretty sure 1993 is a head breather? Looks typical of a head breather that is ingesting a little oil.
If not a high high mileage engine then most likely cause is mist from the stock air cleaner set up. Umbrella valves probably old and stiff.
Happen to do a compression check before disassembled? Also probably a long term tad rich condition.
How many miles? Does it use oil? Stock engine? Plan on cylinder rebore? What carb and jetting? Need more info. YD
Ok, from the top.
1. It's a 1993 FLHTCU
2. No, I didn't do a compression check first, but that would've been a good idea!
3. I believe the engine is stock (I inherited the bike from my brother-in-law in 2012, he had it in storage for at least 10 years prior to that.I don't recall him doing an significant work on the bike)
4. 48,724 miles
5. I wouldn't say that it "uses" oil, other than what leaks out of it.
6. Stock CVH carb, although I rebuilt it in 2013 (that seems like only yesterday!), but I didn't change the jetting.
7. The spark plug from the front cylinder looks like I'm getting a good burn there.
8. The spark plug from the rear cylinder is black and a little oil fouled.
9. I hadn't planned on doing a cylinder rebore, but ya' know....while I'm at it! But my original plan was a gasket swap only.
10. In general, I was happy with the performance of the bike, but to be honest, it's hard to compare it to my 2015 Softtail or my wife's 2012 883 Low.
The above is good advice...and have the base of each cylinder machined flat if you plan on a rebore or is this just a gasket swap? I highly recommend you give it a good once over on the top end, since it's already apart, and if you live in an area where your bike is down for winter hibernation. How many miles?
Lifters and cam/cam bearing also...let the snowball start getting bigger...YD
I'm in Maryland, so this is a winter job. I've got to Spring to get it back on the road!
All Good But... No Way I "lap" any valve... Either do it right...ie touch up the valve and seat, or Run it.. I'm sure the Seating surfaces are plenty Wide right now...
If the Head side of the valve stems is not Spotless clean [blasted?] more damage can be done dragging the stem thru the guide than you will ever be curing if not all done correctly... again... leave 'em in place or go "all the way"
Truly Flat, and gain a bit of compression ...as 98HRFB states...
I would Not miss this opportunity to replace Cam bearing, and certainly assess how many miles are on the Lifters!!!
Are you suggesting new valves, and new valve seats?
Are you suggesting new valves, and new valve seats?
Certainly Not... Ain't **** to do a Quick valve job, on what you have... and a necessity if you even re-ring, which is a must if disassembled, or of course a rebore..
I never touch the Piston area without the Valve area... and at 48k... if it was a Shovelhead, stock, I would begin to thinking maybe rebuild. on an EVO??
My recommendation??? Leave it alone... Warm it up properly before jockeying that throttle.. Black Plugs do Not concern me...Wet??? Needs addressed..
If you have already Plucked the Cylinders off the pistons... it is too late ... if not... Cool...
Doing base gaskets is fairly easily accomplished by raising the jugs just High enough to get the Wrist pins out...leaving the pistons in place...
After new base gaskets... simply put it all together...and take care of it...
Oh... Peek in at the Valve Guide seals... I have lost them before...and ... there is also a COB way to replace without removing Valve...
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Valve Diagnosis
