Replacing base o-rings, Do I need anything else?
 

I have a leak in my base o-rings on my 2009 FLHX so I bought the Cometic top end gasket kit with .030 head gaskets (guy that built the engine for PO used this and talked to him). Got the book, videos from Youtube, Yamabond 4 for around the base when install new o-rings (builder recommended it), all the tools (nothing special except ring compressor and torque wrench) and beer. Am I missing anything else?

My only hiccup looking at everything is the getting the rods in the right spot for disassembly and assembly.

-Should I do 1 cylinder at a time and then move the wheel in 6th gear so I'm on the compression stroke of the opposite cylinder or do both at the same time?
-Should I replace rod/tappet housing base gaskets as there are no leaks?

The bike has 25K on it and about 15,000 since it was built from a stock 96 to 103 (4 years ago) with Woods cam, big sucker, heads ported and polished, Fat Cats, Wiseco high compression pistons, manual compression releases, DK head breather bypass, ect. The original builder said not to mess with the heads at all unless they look fried and then to call him. I only notice the base o-ring leak and a veeerrry slight loss in power. I think I got some bad gas with water in it on a trip.

Also, there isn't much air coming out of either breathers or sucking in. I don't know if it's supposed to be this way and if that has had an effect on anything and the Big Sucker breather bolts are free and clear. It doesn't really use any oil and my oil pressure gauge is running a little past 32 (probably 38 and comes down when stopped) when it's normally at 32 (have some pictures riding down the road with it pegged at 32). I did an oil change after I noticed it (Mobil 1 and K&N filter) but no change there as I thought maybe the filter was plugged somehow. Oil coming out looked fine and nothing on the drain plug magnet.

Thanks in advance.

So, let's see if I have this straight:

1) "The builder" you mention performed the last build, which is now leaking at the cylinder base O-rings.
2) Same builder is now recommending that you do or have the work done at your expense to correct the leaking O-rings.
3) Same builder is recommending that you use Yamabond on the O-rings.

Did that builder use Yamabond in the O-rings when he built the motor? I have been through four builds of my 2000 TC motor where the cylinder O-rings were replaced. Never used Yamabond or anything else on the O-rings, only made sure that they were free of excess oil when the jugs were pushed down into position onto the cases. Never, ever had a leak in 13 years with any of these builds. HD service manual does not recommend using Yamabond or anything else on the O-rings. Why are you so ready to do this?

I would send the jugs to a quality machine shop and have the base surfaces measured for absolute flatness and have them milled the minimal amount to achieve absolute flatness if necessary and forego the Yamabond or any other band-aid when you put your motor back together.

Thanks for the reply. The builder, who had a shop here in Iowa and a great reputation, did this for the previous owner years ago and did not use Yamabond 4 at that time. He said he personally has a 117 with no o-rings and just Yamabond on it with zero problems in 40K miles. He retired and now lives in FL but the PO gave me his number if anything would ever come up. He suggested an ultra thing layer on the case, not actually on the o-rings, and I thought this might be a little extra insurance since it didn't have it before and he wasn't doing that at the time when he built my motor for the PO. I would still install the o-rings no matter what. I don't think it's necessary but he said he started doing it the last couple years he was building. Both cylinders just started leaking at the exact same time and have always been dry as a bone up until a few weeks ago while I was on a trip. Please feel free to give me more opinions as I'm open to suggestions. I like wrenching myself and hate to pay someone for something I can do on my own. I certainly don't trust the stearlerships. Thanks again.

I appreciate you taking my feedback in the (helpful) spirit that it is offered and I respect and applaude you for doing the wrenching yourself. If you do not intend to have the cylinder bases inspected/measured by a machine shop, you can save a lot of time and money (cylinder honing and new rings) by lifting the cylinders and pistons off as an assembly. Once the heads are off, cut some 1/2" PVC pipe to about 4" length for spacers and cut a groove lengthwise such that the spacers will fit around the cylinder studs. With the assistance of a competent buddy, lift the cylinder up just enough to get clear access to the piston pin (and NO MORE, less the oil ring become unseated), insert the four PVC spacers around the studs to support the cylinder. Carefully cover the exposed holes in the case with clean rags to avoid dropping anything down into the cases. Then remove the piston pin circlip from the right side and then drive the piston pin out from the other (left) side. Carefully and slowly lift the cylinder and piston assembly off of the rod and the studs, being very careful not to let the oil ring become unseated at the bottom of the cylinder bore.

Do the second cylinder/piston the same way. Do not rotate the cylinder or piston in relation to each other, thus not disturbing the piston ring/cylinder coupling, bag them to maintain cleanliness, and set them aside in a safe place out of the way.

Put a minimal amount of motor oil on the O-ring and slide it over the bottom of the cylinder bore, making sure not to twist it and that it is seated correctly at the base of the cylinder.

Carefully work the cylinder/piston assembly down over the cylinder studs until the hole in the piston land lines up with the rod bore and drive the piston pin through the hole in the piston land. Replace the circlip removed during disassembly with a NEW one. Check the O-ring to make sure that no excess oil is present, wipe it off with a clean rag if there is. Remove the rags covering the bores in the cases and slowly slide the cylinder down until it firmly seats into the case and then secure it in place with two short head bolts using ~1.5 inch long 3/4" diameter PVC spacers. Do the other cylinder the same way and then reassemble the motor, making sure not to rotate the crankshaft once the head bolts and spacers are removed until both heads are correctly torqued into place.

Never used Yamabond or anything else on the O-rings ... Ditto ... Yamabond is great for sealing case halves and the like but NOT FOR RUBBER PARTS

I appreciate the how to. What is the benefit of doing it that way vs just pulling the cylinder off and reinstalling with a ring compressor (I have one)? How am I saving a lot of time by doing it as you have instructed because I'm still tearing everything down? If I can't get that wrist pin out, which can be a bitch from what I've seen and read about, I don't have a puller and don't want to mess anything up because then I'm really in a word of hurt. I'm sure I could make some type of puller but don't want to F it up. Thanks.

EDIT: I was also going to clean off the piston tops when I had the jugs off because I'm sure they are nasty but I guess I'll see.

It wouldn't be on any rubber parts, just metal.

Oh, and I've rebuilt many 2 strokes (motorcycles and snowmobiles) but not a 4 just for reference.

You save time and money by avoiding cylinder honing and new rings once you disturb the rotational relationship between the rings and the cylinder bores.

I did exactly as I described in my prior post last December and had no issues with removing the circlips nor the piston pins. Use the appropriate sized deep well socket and a dead blow mallet to drive the pins out and back in. Works like a charm.

Carbon can be safely cleaned off of the piston top by bringing it to TDC, taping off the piston top to the cylinder top with duct tape, and then using a wire wheel on a drill, air grinder, rotozip, or Dremel tool to blast the carbon off. Did mine with a drill and a wire wheel. Clean as new.

Your motor, your money, your call.

Hey, I appreciate it and why I asked. I didn't know that I would need to put new rings and hone if I simply slide the cylinders off. When I've done 2 strokes you can simply cross hatch if they are worn but they usually are not (on snowmobiles anyway). I'll give your way a shot. Any advice on the push rod install other than having the cylinder you are working with on the base circle?

Some will say that it is okay to disturb the rings, but I have seen first hand the importance of optimal ring seating/sealing, so I choose not to take the risk.

Re: pushrod adjustment, S&S has a good YouTube video on that and there are many here on the forum that have their own technique. Hopefully, they will chime in. The main thing is to make sure that you have the piston and cams at the right position, tighten the adjustment the proper number of turns based on your lifters' travel and your pushrods' threads-per-inch, and that you can spin the pushrods with your fingers before rotating the crankshaft (lifters have completely bled down).

Those were the set of videos I was talking about having. I believe I have stock pushrods in mine and not the adjustable or quickies. The builder didn't remember since it was several years ago and I haven't pulled the tubes to look.

I just took a peek and my push rods are adjustable so I'll follow the procedure on the S&S video that I have saved from YouTube for adjustment and bleed down. If anyone else wants to chime in please do so.

Started my tear down and got the front pulled apart. Holy cow was the piston and head full of carbon. Just mounds and chunks that took me at least an hour to clean the one head and piston. There has got to be an easier way than using a brass wheel and scrubbing with cleaner and brass brush. I'll do some searching.

I went ahead and installed the DK breather bypass for my big sucker intake and also going to go to a canned tune in my PCV. The guy that built the motor put a custom tune in it from another build he did that was put on a dyno but it has always run rich. There is no way it should have this much carbon with about 15K on the build. I'll get it dynoed after it's all said and done but I pulled the piston in the cylinder just as you instructed, dynawg1. I have my top end kit and need to get a couple circlips for my Wiseco pistons (don't think they are the same as HD). Wish I could just use the one I took off since it looks totally fine and not warped at all. I assume the other back cylinder will be the same. Hopefully a local shop will have them for my Wiseco pistons or I'll order them online.

I'm going slow as to not make any mistakes since this is the first time I've ever pulled a top end on a HD. Not hard at all, just takes time. I know if I would have taken it somewhere they wouldn't have cleaned the piston or head and slapped it back together.

Good progress. You can use a drill, die grinder, rotozip, or Dremel tool with a wire wheel attachment to remove the carbon from the other piston and the heads' combustion chambers. Make sure to clean the heads/cylinders/pistons/rings very well afterwards with compressed air and brake cleaner until a wiping rag shows no black residue and then rub down the cylinder walls with clean motor oil, ATF, or Marvel Mystery Oil before reassembling. STRONGLY recommend AGAINST reusing the circlips!

Bypassing the crankcase breather mist away from the air cleaner should significantly reduce the carbon buildup, but overly rich AFR will cause it to return quickly. Need to get a good tune on a Dyno. I use 4-5 ounces of Seafoam every 4 tankfuls of gas to eliminate any carbon buildup.

I did the Dremel and drill with a wire wheel and it still took forever. I think I'll put some Seafoam on a sponge and set it on top to soften things up. I'm taking your advice and WILL NOT use the same circlip and wondering if I should just go ahead and do the rings as well after seeing how caked everything was. I don't know if they are stuck because I did notice a slight power loss when my bases started to seep oil. Or if I should put everything back in and run several tank fulls with Seafoam. I can't say that I'm using too much oil before or seeing smoke but time is no big deal, I have a ring compressor and what's another $60 total at this point? I can take the cylinders to a shop and they will run a hone through them for $5 each and had them do it on snowmobile cylinders before. Thoughts? Again, I appreciate the help.

Not a good idea to use a wire wheel ( of any type ) on a piston ... Scraping the carbon off is a better option ... Next time try an old trick ... Without stalling the engine spray water into the intake ... it acts as a "blaster" removing all the carbon very effectively. Good luck with the repair and "happy motoring"

If you're having a local indy hone the cylinders, bring your pistons and rings and have them set the ring end gap as well. And yes Marvel Mystery oil is a great oil to use in the cylinder when re-assembling the pistons. Will help to seat the rings better...

IMHO, if it has that much carbon, I would remove the pistons and clean them outside of the cylinders. I wouldn't want to worry where all that carbon is going.

Of course new rings would be in order. But don't just have a hone run through it. these rings require a specific hone job, cross hatch and stone grit are important. Along with torque plate.

And by no means would you reuse a cir clip. no a gamble worth taking!

Thanks, Larry. I had already done that with Seafoam and water mixture. I scraped as much as I could with a razor blade before using the wheels.

The shop uses a ball hone for their work to create that crosshatch.


Good idea.

Personally, I wouldn't settle for a ball hone.

Oh, and I had the wrong ring kit number. I checked the part number on the top of the pistons and I was off. The real ring kit is 3875VM and Amazon shows them for less than $6 per set with Prime (which I have) but even though they show 2 available they are not. I chatted with a guy from Amazon and was going to even do next day for a total of less than $20. Damnit!!!

You know, I guess I'm just going off of what they do for my sled cylinders to get that nice crosshatch when I have them honed. I'm sure they have done thousands of these and know what to use. I'm certainly not an expert on HD cylinders as you can plainly see. :icon_nut: Appreciate the input.

Thought that a re-ring was not part of the plan based on earlier posts, but can't hurt if there is enough material left in the cylinders' bores for a proper hone (plateau hone is best) without exceeding clearance specs. Have a machine shop measure the piston skirt diameter .5" up from the bottom, add the piston mfr's clearance spec, measure the current cylinder bores' diameter, and decide if there is enough there for a hone. All this can be done with the pistons and rings still in the bores. If any doubt leave everything together and reassemble as is after a thorough cleaning and relube. Re-ring should really not be necessary with only 15k on the motor unless the cylinder walls show scratching or abnormal wear.

Just got the other side off and both bores look fantastic. No scratches and still see cross hatching. Was a bitch to clean piston and heads again too but oh well. Brought piston to the top, cleaned off, blew stuff away with leaf blower, brought piston down a little, scraped inside cylinder edge, blew out again and wiped clean, dropped down a little further cleaned, again, then pulled the piston and cylinder together. I'm torn on whether to do the rings or not. If I don't all I need is 2 circlips and I'm ready to go.

BTW, how the hell am I going to torque anything in the back rear cylinder??? I had to cut off the end of a 7/16 little 1/4 driver and grind down part of the socket well itself then use a 1/4 to break the bolts loose and get them out. The 6 bolts in the rocker base plate was a bitch!

Sounds like a re-ring would be a waste of time and money IMO. Appears that you are doing a top-drawer job. At this point, cleanliness of the parts is the top priority. Clean everything as well as possible with brake cleaner and a clean rag until no black residue comes off on the rag.

Regarding reassembly, the head bolts should torque up fine with no interference problems. Pay close attention to the rocker support bolts - front and rear are slightly different. You may need dog bones to torque some of the rocker support bolts and rocker cover bolts. There is a recent thread here about where to get the dogbones as well as advice on how to complete the job without them by our friend djl.

You are installing new headgaskets, correct?

I bought the full top end Cometic kit with 0.30 head gasket so I'm good to go. Just need to make sure I don't miss and gaskets or o-rings on reassembly. I've got the book on pdf but believe the Cometic takes different torque specs. It hasn't been hard up to this point, just takes a lot of time. I'm making sure I go slow and do it right. The only thing I'm worried about are the pushrods and adjusting them but will watch the S&S video again. I pulled them out and marked them and could reinstall like solid rods but the builder told me 3.5 turns on them. I watched the video a few times for disassembly so didn't even need the book or anything else when actually doing it. Thanks!

dynawg1, do you have a picture of the 7/16" and 1/2" dog bones I would need? I've done some searching but there are different types and I saw that someone found them at Napa for about $13ea. I'd appreciate it!

A good 3/8" torque wrench should clear everything. It's what I use and have no problems. Also a ball hone is good for cleaning cylinders and not cross hatching. If you're doing your brakes calipers they'll work there.

Ball hones are great on nikasil cylinders (snowmobiles). It actually deglazes (many refer to it as honing) them to reveal the factory crosshatch and I should have made that more clear. I assumed the cylinders on the bike would be similar but obviously they are not. Like I said before, I'm new to rebuilding a HD. 2 strokes and 4 strokes are totally different animals but I'm probably not tell you anything you don't already know. There was no way I could even get a 1/4" ratchet and 7/16" to the rear back bolts on the rocker base. I have no idea how you could get a 3/8" torque wrench back there. I have 1/4" and 3/8" torque wrenches so I'm covered there.

This is the one that I bought:
http://www.amazon.com/gp/aw/d/B001HW8Z0C#searchKeyword

That's what I thought but didn't want to assume. Do I need to worry about torquing the 7/16 on the rocker base plate or is doing it by feel based on the ones I can get to okay? If no, do I even need to buy a 7/16 extender? The 2 bolts on the primary side are the ones that are a bitch to get to and I couldn't even get that down in there unless it has an off set well. Also, the previous builder used loctite on all bolts but when I watch the S&S video he only uses assembly lube. Opinions? Again, thanks for helping and answering my questions.

No Loctite. Clean all threads, male and female, with a thread chaser and the males with a wire brush or wire wheel to ensure that they torque properly. Put bolts into the rocker support plates before you fit them to the lower rocker cover. The 7/16" dogbone is optional IMO, but good to have and use for peace of mind since you have to order the 1/2" dogbone and the circlips anyway. Follow the S&S procedure and make sure to also put motor oil on the headbolt threads prior to installation.

I just pulled my heads 2 weeks ago and had no issues. Maybe I'm mistaken. I will pay closer attention when reassembling and let you know how it went. I've done my heads several times and never had an issue. Sorry if I confused any one.

:icon_toast:

I can't find that 1/2" torque adapter anywhere around Des Moines, IA and would have to order it, which would take about 5 days to get to me. Dammit!!!

How about using a crows foot wrench on the end of the torque wrench? Would that work? I know I can get the the head bolts no problem and those are 12pt. Harbor freight has the crows feet cheap and don care if I have to modify them.

http://www.harborfreight.com/7-piece...set-93137.html

or

http://www.harborfreight.com/7-piece...set-94426.html

Don't worry about getting a torque wrench on every bolt with the exception of the head bolts. Torque the ones that you can and tighten the others by "feel". I have done this for years with no issues. Sometimes it is necessary to wedge an appropriate object between the frame and the rear rocker box covers to push the motor down enough to work those two rocker cover bolts you are having trouble with; push the motor down with a suitable tool and wedge a block of wood between the frame and rocker box to hold it down while you work.