trap door and motor case questions

[gabbyjon]

Mating a 56K right case to a 54K left case with trap door:do you see any problems assembling the 2 together?Does it require any special machining? On the trap door:The 54 case did not come with the trap door.I have a door from what I believe is an early XL with a threaded hole for a center mount primary bolt but not the raised boss such as the correct door would have, also it doesn't have the conical dowel pin holes.The door does not align very well on the right case as it would not bolt down flush to the case.At present the motor is in the hands of the mechanic-machinist working on putting all this together so I am going by memory on the info I am supplying.Can the early XL door be used on a K model or should I try to locate the correct door?Will the primary cover bolt up to the door without the raised mount?Could I just use a spacer?The mechanic is quite capable but when I last spoke to him he was telling me about the problems he was encountering with fitment but not in much detail about the solutions.So I thought maybe the people here could explain further on these issues.Not sure if this all makes any sense to the experts Im still learning about the K motors,Thanks for any help you can provide.

[EKHKHK56]

According to the H-D company each door is made and machined to the parent case it comes with. People do swap them around out of necessity. I would think getting a door with the conical locating pins would increase your chances of a good match. Close inspection while fitting transmission together would tell more. People that separate the doors from the cases should be shot, at least once, in the foot. Like the 55KH that was pieced out on ebay last month. They sold the trap door separate from the nice cases!!! They also sold the custom valves separate from the cylinders. Makes no sense except just to get more money. Anyway thats my opinion. Erik K

[MTaylor]

An excellent point of trap doors. They should stay with the parent cases always.

[55panman]

Yeah, the trouble with that is most of these K model basket cases have been shuffled so many times through different owners that parts went missed or other parts got mixed in. Remember for a lot of years no one wanted these things. 70's 80's early '90's I swapped a set of Shovelhead (weren't eve that cherry) rocker boxes for the first one I got back about 20 years ago. Ron

[gabbyjon]

Thanks much for the info,I thought this was going to be the answer but i have other people telling me that the parts are interchangeable such as case hales and such.

[sportsterpaul]

I have heard people say it is not worth trying to mate two unmatched case halves together. You have it even worse since you are mating across model years with the wrong trap door.

First headache is the cylinder spigots, the big holes where the cylinders mount. The factory machined those with two specific case halves mated together. The top surface is dead flat for the cylinder flange, and the hole is perfect, with no little "steps" where the two halves meet. I am told a rock-star machinist can pull the studs and machine the deck with a file-- I am doubtful of that. Otherwise you jig the assembled cases in a Bridgeport or other knee mill and deck the cylinder mating surfaces with a flycutter. If the steps across the halves are small enough to let the cylinders in, well, you lucked out. Otherwise you have to true up those big holes so the cylinders slide in.

OK, now the cylinders fit, but you have to make sure the flywheel bearing are co-linear. They can't be off centerline, even a few thousandths will screw things up. So there is a line hone you can buy from Eastern or most mechanics use a Sunnen hone with the right tool.

You have even more problems without a "mated" trap door. If you have cone dowels you have to find a cone dowel trap door. Either than or get the cones out, locate the right half in a mill, slap on the left half after removing the cones, and then move around the trap door until it matches the mainshaft and counter-shaft holes in the right case-- exactly. Then you hard-clamp the trap door and machine new dowel pin holes and install the dowels.

Even that is not enough-- you need to assemble the empty cases and trap door and line-bore the mainshaft bearing. You can use the Eastern 200-dollar tool, or a Sunnen hone. I showed using the tool in this article. There is a table on the last page showing the tools, including the one to hone the crankcases. Sorry, I don't lend tools or work on other people's bikes, but there are plenty of good machinists out there. You need a machinist, or a very very good mechanic.

If your left case has trap door cone dowels, I would beg one of these fine gentleman for a cone-style trap door-- then do the line-hone and you might be OK.

[gabbyjon]

Well it sounds as bad as the mechanic made it sound.the work is being done by Craig from Lockwood engineering also known as black widow cams.I believe he is quite capable as a machinist-mechanic he stated the motor would be completely blueprinted when done.There is a local guy who is quite familiar with all these problems and capable of doing the work but has hung up his tools for a job in the medical field.He actually has what is thought to be the only known engineering drawings of an xl motor but would not part with them as he is selling them with his business.thanks for the insight

[55panman]

I have mated up mismatched cases successfully and I'm definitely not a rock star machinist. My Bonneville recording holding vintage gas 1955 Harley Panhead had mismatched cases the first time I set a record with it. You need patience and to take your time. I put new bearings in then bolt up the cases and have my man line hone the races. I then put the crank in and again bolt up the cases. I've done this with a crank knocked together without rods and also done it withou the crank. Then check your cylinder base deck alignment. Pul the studs and put some dykem on the surfaces. Using a single cut aluminum file works best to start, google it, PFERD, shows one. Cut at an angle across the base surface. Don't drag the file straight across. You can use some chalk to keep from loading up. Use a file card often to keep from loading up and scratching face. File from one side then the other and be sure to take your time and keep the file flat. After dykem flushed off color again then use a fine file. Then color again and I use a 1 inch thick plexiglass bock like you would use a sanding block to block sand your painted gas tank. Wrap a piece of fine emory paper around the block, dykem the base again, and sand the bases with the emory paper, again changing the emory paper as needed, and making sure to keep the block flat. Your travel area is limited but it can be done. Being a welder I have also used this method on cases where I made a weld repair on the primary cover surface, filing down the weld then block sanding, primary covers (they're hard to put in a mill to flycut), and timing cover areas, and timing covers. Done many times over the years with no leaks.

[55panman]

Oh, another thing. If you were to use the file method: When you bolt the cases together for the final, torque the cases, then loose the case bolts slight, put the cylinders on and tighten down the cylinders then re torque the case bolts then torque the cylinders.

[sportsterpaul]

Ha, 55Panman, I am in awe. Yeah, your not a rock star, the way Jimi Hendrix was a just backup player for Wilson Pickett. What I love about this forum it that it's not full of people that heard it from a cousin of the friend of a friend, but guys that actually did the work. It was guys like you 55Panman, legends, that my pals in San Jose must have been talking about truing a case deck with a file. I knew Duncan Keller and Vance Breese, and both went to Bonneville. Maybe that is where they heard about this.

I think you agree that the deck is much more important than any little step in the side of spigot. Nice instructions on making it dead flat and smooth. I have found those thin paper gaskets work fine on good surfaces. I hear that some early models did not use a base gasket at all.

The worry is that the OP (original poster) has different year case halves. Things were pretty sketchy at the factory back then. Lets hope the spigots are close. I have heard from racers that line-honing the tranny mainshaft bearing the right case is critical. That is not to say he could not get away with it being off alignment, but that is a ticking time bomb. My pals say it blows second gear with the bearing mis-aligned. But who knows, maybe if you baby the bike, it will be OK.

gabbyjon, it sounds like you have some top-shelf people on the project. If you are worried you are getting ripped off by needless work, because you have some friends saying you can just slap this stuff together, don't worry, it really does take a lot to properly assemble these mis-matched cases. I think guys like 55Panman are doing the right thing-- making due with available parts-- its the "real man" thing to do, and it makes for much better stories when you are bench racing.