1912 HD Belt Twin (AKA EVIL TWIN)

[Slojo]

Road Trip

Well greezy bikers, finally a long anticipated road trip of 1200 miles round consumed my weekend . Purpose, parts chase. This trip was first attempted in November or December but canceled, snowed out.

With a friend at the wheel we traveled to parts unknown in search of those elusive missing items for each of our projects, mine, parts for this twin. After a day of digging through a personal collection of parts the twin gets an original 1912 rear stand , a decompression / spark control drag link , one good inner and outer control cable and cable nut assembly , complete belt tensioning assembly , two sets of early spokes including nipples , a 23 inch clincher rim with ...count em.... 40 punched spoke holes and some miscellaneous small bits.

Forty spoke hole 23 inch rims are rare rims that for production Harleys were used exclusively on the rear of 1912 twins , they were also found on Board Trackers the latter with safety wire tided and soldered spoke crossings . Typically 1912 and earlier 23 inch rims are 36 spoke holes and 1913 and latter 22 inch rims are 40 spoke holes. This excellent condition 23 inch rim will not be used for Cannonball service but will supplement the twin for after Cannonball activities where a switch of wheels returns the bike to authentic chassis condition. Yes, for Cannonball the chassis will be stock excluding brakes tires and rims.

Back in the shop anther hub piece is in the machine, set up and first part run off. This time an internal brake anchor, it is a modified from original item and is part of the incorporated braking safety. Back on the job today an early finish with a customer sent me off to the east side , Apollo EDM.

Apollo will do work that will be instrumental in the coaster . Left behind with Apollo are fourteen coaster shifter sliders to be EDM (electrical discharge machine) for an internal multi start thread lead . This EDM process typically would be broached in a production situation. More on that latter.

joe

[BigLakeBob]

Keep posting, still enjoying your progress. You must never sleep.

[Slojo]

Bits and pieces

A trip to Lyndon Fabricating to pick up some 1/8" cold rolled steel for fabricating belt tensioned parts followed by a run to a new welding source in closer proximity to headquarters. While at Lyndon Fab. they sheered and bent plate steel for my belt tensioned bracket. Belt drive twin tanks are non existent and chain drive tanks are without the brackets required for a belt tensioning ratchet plate. I fabricate a bracket that picks up of the top motor mount and holds the ratchet device along side the left gas tank.

Wendell Turned a local custom bike builder and friend happened to be at Starlight Welding when I rolled in . Wendell introduced me to Starlight's Andy , a polite , easy going personality. After conversation with Andy I left my cylinder behind to have a large cooling fin welded and a repair to the cracked exposed portion of the valve guide.

A couple hours later the cylinder was ready for pick up. Welders are worth their weight in gold, fortunately a much better deal was had than paying pound for pound in gold to get my work done professionally.
Thank you Andy.

The next cylinder process is to have them stress relieved prior to finish honing .

Back to the barn for some quality machine time where coaster brakes are still the focus and will remain so for a while. I am down to making two primary parts for the rear hub and some secondary parts to follow. The coaster device with its new design friction generator works perfectly and should not be a problem unlike the original coaster device. This is an important device, if it malfunctions brake function and pedal starting becomes impossible the pedals spin freely in both directions. Without pedal engagement...... fun ceases.

Side note, Knucklehead parts are on order for the 37 motor project now in process.

joe

[Slojo]

Spring and Things

The rear cylinder bore cleaned up much sooner than the front cylinder, clean size is 3.326" rear 3.334" front. The next decision is weather to match the bores or run two different size pistons. With the scarcity of matching 1912 cylinders mismatch pistons sounds just fine even if it is only .008" . A call to CP pistons will determine final bore sizes. The finished bore size is ultimately determined by the ring manufacturer.

Last night was a late night programing setting up and making three prototype coaster parts on the Okuma . Once completed with that task a trip to the spring shop was scheduled.

Off to the spring shop for a spring curling marathon to accompany the coaster part of the coaster hub. These compression springs (.03 wire,7/32 OD X 3/8 long) will be part of the friction device that assist the coaster to slide left,right. Bill twisted the springs faster than Timothy Leary can twist up a .......oh slipped . Another fine job by the guys at McGuire spring.

Afterward a trip to the east side to see a customer , followed by a trip to the shot peen shop where my connecting rod set was treated to stress relieving surface shot blast.

Rod races , bearings , cages , and a modifiable big twin crank pin ordered and should be in next week . Many of the motor parts are coming together while working on the coaster hubs. Careful preparation of all the pats should cause for an assembly marathon in the not so distant future .

On to the other project, Knucklehead heads are troubling. I have late model rocker tins and need the early style that have the offset to clear the rabbit ears casting shoulder. A set my have been located , stay tuned.....

joe

[Slojo]

Cylinders

While preparing for knucklehead action , organizing the many parts required to build a set of heads I also made tooling, a set up, and converted a boring program into an ID grinding program for processing the welded front cylinder on the Okuma . Okuma Jig Grinder???

An arbor made from hardened and ground piece of scrap tooling salvaged from the dumpster worked perfectly for mounting the grinding wheel. Next a fixture mounting plate to hold the cylinder in the machining center was made from an Okuma motor mount plate. Just proves old Okumas never die they just get re"cycled" , into motorcycle tools.

Excess weld material in the front cylinder was machined off using carbide tooling, lots of carbide tooling. The metallurgic make up of the cast iron combined with the silicon bronze (and possible tungsten from the TIG torch) caused carbide eating hard or abrasive spots while machining. Once close to size , grinding became the obvious answer to the problem.

Fellow Cannonballer Chris Price will finish hone these cylinders , damage to his honing tools will result if the weld is not cleaned up smooth with the bore. In this front cylinder the piston must have been reciprocating sideways with a twisted bent connecting rod for some time prior to the wrist pin destruction.

Front cylinder bore measured 3.307 at the bottom of the stroke where the least amount of wear takes place. An unusual wear pattern required excess valuable material to be ground out of the cylinder bore. End result, finish bore size grew to 3.334" nearly .030" over bore. The rear cylinder may get a smaller piston if it cleans up early in the process.


On to the next problem, the finished cylinder had an issue where the bore meets the open combustion chamber . Either casting shift or qualifying of the cylinder during OEM manufacturing caused for the bore to terminate into a shoulder where their should be an opening larger than the bore.

Blind hole cylinders are difficult for this reason alone. A 5/8" carbide burr and a six inch extension mounted in a slow spinning drill motor made quick work of the problem easily cutting away minimal material for hone clearance.

joe

[Slojo]

It appears Cory's email address has failed on the receiving end.
joe

[Slojo]

Key Number Yesterday 80

The Monarch lathe was perspiring heavily yesterday and it wasn't even working hard. To much great weather to soon permitted into the shop , everything including the floor is wet and slippery from condensation. De-Humidifier season in Michigan is much better than heater season.

Five days into the connecting rod project, the rods are ready for steel shot penning .
Today the cylinders will be bored for clean up size validation in order to know what size pistons will be required. An order will be placed with CP pistons again as I know what to expect from their pistons as relates to clearances and durability.

Photos to follow if Cory is awake up their in the mountain country. Time is running down, an hour and a half has gone into preparing this article and photo down loading this morning. Finding and sorting photos after downloading is the greatest time waste. Brevity may be the key from now on.

joe

[Slojo]

"edit post" and "save" function aredisplayed and editing is possible in the temporary file it just won't transfer to the permanent file that we all read from. HELP!

[Slojo]

Trouble in Paradise

After posting an article in the hazy evening hours a reread will turn up a misspell or grammar error. In the past this could be easily rectified within a day or so, now it is locked in. An edit function is displayed and editing is possible in the temporary file it just won't transfer to the permanent file that we all read from. HELP!

joe

[rwm]

Why does the edit function no longer work?

they national voted to move it to buzz's forum

[fillibuster]

Why does the edit function no longer work?

"Why does the edit function no longer work?" ..... edit/copy/paste off the top tool-bar? ... no? .... not what you meant.....

[Slojo]

Why does the edit function no longer work?

[Slojo]

Coaster, on the Skids

Temporarily side tracked from the coaster project and redirected to cylinders and connecting rods.

The cylinders are a matched set by serial numbers and are original 1912 only cylinders. I acquired this set of cylinders not as a set but individually with several years between the acquisition . These cylinders are with standard bore and near perfect condition . The only flaw is a couple damaged fins and one cylinder is with a wrist pin grove worn in its bore. To get one of the cylinders I had to convince Danny (he loaned his 1914 twin during the Ghost build for reference) to extract the 1914 twin motor form his running bike, remove the 1912 cylinder and trade it for a 1914 cylinder (supplied by yours truly) to correct both of our bikes. Coming up with a 1914 cylinder was no easy task but accomplished !

After months of deliberation on cylinder repair a decision was made to TIG weld the wrist pin damage with silicon bronze. The damaged 1912 cylinder was sent out for repairing the wayward wrist pin damage. Process, preheat the cylinder to 500 degrees and run the weld, reheat and the burry it in floor dry for a slow cool down process. No pinging or cracks !

I can now cut the cylinders and get a finish bore size for ordering pistons.

Three days of machining and the connecting rods are near finished. Reused the scrap female rod (invert the Y axis, remember?) from the Ghost project to make a male rod for this Twin. Rod races , donor crank pin blank and bearings are on order and will halt the rod project just in time to get back on the cylinder and coaster processes.

[c.o.]

Cory

How observant , actually the seat suspension had fallen apart and required some attention. Pat brought the Henderson for its first meet and it experienced a seat failure.

joe

So you're saying the experience was a pain in the a$$? Nice strategy with "keeping the enemy close".

I like a good lightning storm. That is, if it's followed by heavy rain. Forest fires suck. So would major machine equipment failure! You need some sort of steam powered, belt driven type backup!

[Slojo]

Mushroom Season

While near completion of developing a new part program for the next hub part a wild lightning storm rolled in, juice everywhere. I don't take chances with my equipment in electrical storms so the best thing is to shut down for the evening. One good blast could cost way to much.

An order placed today for a Big Twin crank pin, Sportster big end rod races, rollers and cages . The crank pin over all length will get cut to a new length , new tapers ground and rethreaded to suite my application. Using a finished crank pin saves heat treat and finishing of the O.D. This is the same procedure used on the Ghost.

joe