"Big Tank" Crocker OHV motorcycle by DocRob - Model Factory Hiro - 1/9

[Egilman]

20 minutes ago, CDW said:

You do mean 600cc, I'm guessing? 60cc is minibike size displacement.

Sorry, Cubic Inches... not cubic centimeters... And it is definitely a point/condenser/coil engine, it's the reason for the center wire, Magneto's don't use a center wire...

Edited May 31 by Egilman

[Egilman]

Here is a pic of the left side of Crocker engine # 36 61 8, a 61ci with hemi heads built in 1936 and recently restored... it is the eighth engine manufactured by Crocker... Point/coil ignition it clearly shows where the original coil is located and where the shielded coil wire runs on the original bike...

Clearly it is mounted as far away from the plugs as it can get... to the rear of the seat post below the seat, in front and above the battery... You can even see the ignition wire that runs down from the tank mounted switch....

I have a few more pics of this bike, it is a small tank early version but the engine is the same...

There was only 33 of these engines built before they changed the design to something visibly different...

 

MFH probably ran that wire to the closest point to make it disappear rather than to it's correct point... Or what they modeled is a different engine than the 61....

 

the only thing I can think of...

 

Hope it helps..

 

UPDATE: I started a search on this kit and the various examples of it being built, unfortunately the stock builds of the kit do not show an ignition coil in the kit.... there were two versions of the coil used on the Crocker ignition bikes,,, the early small tank versions, 2 gal gas tank) show a sideways coil like the above pic and the later large tank versions, (3 gal tank) show a coil that is shorter and fatter facing fore and aft in orientation... All mounted to the seat post above the battery....

 

I guess  MFH missed it....

 

 

Edited May 31 by Egilman

[Egilman]

Another update... Haven't a clue where the original coil is located, I"ve seen a lot of these in pics where the coil is all over the place, but those are not original, they have been updated with modern ignition components...

 

Here is a real scale exemplar of the MFH  Model...

 

https://www.mecum.com/lots/380383/1940-crocker-big-tank-big-twin/

 

A 1939/40 model, and yes the coil wire goes up under the tank and then disappears there... No coil behind the seat post either... Although there is a voltage regulator there,,,

The only thing I can think of, they were hand built one off machines, it was part of their advertising that each one was different.... The base engine was a stock 61ci but it could be ordered at up to 81ci.... (only way to tell is to take it apart, no real records survive) Although the engine size was stamped into the block when manufactured, it reads as three numbers, year, (first two digits) ci displacement, second two digits) and serial number... (up to three digits) Also, there were just a few of them built between 1936 and 1942  no more than 150, they ceased building them when they contracted to build airplane parts for the US government during WWII... Shortly after WWII they built a few more from leftover parts, and that was it, they quit manufacturing them in favor of aircraft parts... Essentially, they made no real money off production of these bikes, it was considered an "Enthusiast's" bike where the Harley's and Indians were considered an everyperson's bike, ie. very thin profits for Crocker.... So they were never real profitable and WWII killed them off...

[DocRob]

17 hours ago, CDW said:

If there is a distributor there must be a coil and a coil wire to the distributor.

 

15 hours ago, Egilman said:

It's a Crocker 60cc engine, late model, it carried a point/condenser ignition, the center wire is a coil wire.... The coils of that era were usually a box mounted somewhere on the frame usually above the spark plugs....

 

Up under the wings of the gas tank was a common spot... 

 

And yes the Crocker had a mechanical spark advance on the magneto mounted engines... It was controlled by the left handgrip and needed constant adjustment, ie. there was no "zero" point you kick started it in full retard and adjusted it on the fly... It took some skill to ride a Crocker... But they were the fastest thing on two wheels of that era...

 

Crocker had an open offer to pay anyone that was beat by a Harley or Indian on the race track, he never had to make any payments to anyone....

Muchas gracias amigos, you solved the mystery to a classic bike noob like me. The Crockers were hand built and all a bit different in the end. Some examples show said coil mounted onto the frame visibly in front of the engine, with others it´s hidden under the tank.

I think Egilman is referring to the 61 cubic inches or about 1000 ccm leading to about 65 hp.

[DocRob]

12 hours ago, Egilman said:

Here is a pic of the left side of Crocker engine # 36 61 8, a 61ci with hemi heads built in 1936 and recently restored... it is the eighth engine manufactured by Crocker... Point/coil ignition it clearly shows where the original coil is located and where the shielded coil wire runs on the original bike...

Clearly it is mounted as far away from the plugs as it can get... to the rear of the seat post below the seat, in front and above the battery... You can even see the ignition wire that runs down from the tank mounted switch....

I have a few more pics of this bike, it is a small tank early version but the engine is the same...

There was only 33 of these engines built before they changed the design to something visibly different...

 

MFH probably ran that wire to the closest point to make it disappear rather than to it's correct point... Or what they modeled is a different engine than the 61....

 

the only thing I can think of...

 

Hope it helps..

 

UPDATE: I started a search on this kit and the various examples of it being built, unfortunately the stock builds of the kit do not show an ignition coil in the kit.... there were two versions of the coil used on the Crocker ignition bikes,,, the early small tank versions, 2 gal gas tank) show a sideways coil like the above pic and the later large tank versions, (3 gal tank) show a coil that is shorter and fatter facing fore and aft in orientation... All mounted to the seat post above the battery....

 

I guess  MFH missed it....

Oops, I missed the start of a new page and the even more detailed information, Egilman, thanks for that. I studied a lot of pictures from various Crockers and all seem to be different in details, specially the ignition system. I cannot tell, which of them are original or have been modified later. The condenser coil seemed to have been all over the place, in front of the engine, under the tank and like on your pic behind the engine, which I haven´t seen before on my pictures.
When I look for the MFH pictures of the ´Small tank´ model, there are lots of differences to the later ´Big tank´ version. Like on your pic, the coil is mounted behind the seat post. The later big tank allowed to hide the coil under said tank.

Cheers Rob

[DocRob]

I achieved some important progress today, marrying the engine and the frame. Luckily casting precision and design is very good and I had only a little wiggling to do, while join the numerous connection points of the engine bearing plates to the engine.
The frame itself needed some bending, to accept the engine, which I did before painting. The cast material is durable but easy to bend an very good to work with, luckily. 






 

Cheers Rob

[DocRob]

I added the ignition wiring, spark plugs and the mysterious third wire, which leads to the hidden condenser coil, the shift rods and gearbox. The alternator and battery are finished, but only mounted temporary, to determine the length of the wiring. The only "AM" used is the tiny bracket, which holds together the ignition wiring. I fabricated it from tin of a wine bottle cap.
So far no real worries except a wrong aligned part (my fault), which needed to be pried loose. Luckily I was test fitting the following assemblies and noticed it. Electrical wiring is a bit tedious, as there are tiny PE parts to bend, to accept the un-isolated wire, which easily slips out before gluing. You learn to like Tamiya manuals, where they show you the length of the wires, but apart from that, the MFH manual is pretty clear and easy to understand.




 

Cheers Rob

[Egilman]

1 hour ago, DocRob said:

I added the ignition wiring, spark plugs and the mysterious third wire, which leads to the hidden condenser coil,

Hi brother...

 

I think a bit of explanation is needed here... All ICE's (internal combustion engines) manufactured today use electronic breakerless ignition controlled by the vehicle's CPU... Going back about 50 years the standard was a coil ignition and the Breaker function was provided by solid state components in an electronic module to provide the magnetic field collapse needed to fire the plugs...

 

Prior to that the standard was breaker point ignition which had been around since the early 1900's... The breaker point system consists of a set of Breaker Points, a Condenser, (capacitor) and a Dual Windings coil... (a voltage step up coil)

A breaker point ignition system has two circuits a primary (energizing) and secondary (discharging) circuit and how it works is simple....

 

The primary circuit carries low voltage... (12 volts) This circuit operates only on battery current and is controlled by the breaker points and the ignition switch.... When the ignition key is turned on, a low voltage current from the battery flows through the primary windings of the ignition coil, through the breaker points and back to the battery... (to ground) This current flow causes a magnetic field to form around the primary coil....

 

The secondary circuit consists of the secondary windings in the coil, the high tension lead between the distributor and the coil (commonly called the coil wire) on external coil distributors, the distributor cap, the distributor rotor, the spark plug leads and the spark plugs.... As the engine rotates, a cam on the distributor shaft turns until the high point on the cam causes the breaker points to separate suddenly.... Instantaneously, when the points open (separate) current stops flowing through the primary windings of the ignition coil.... This causes the magnetic field in the coil to collapse around the coil. The condenser (capacitor) absorbs and stores the energy to prevent arcing between the points each time they open. By sucking up all this energy the condenser speeds up the rapid collapse of the magnetic field.....

 

The line of flux in the magnetic field, (hi magnetic potential to low potential) cuts through the secondary windings of the ignition coil, creating a very high voltage (50 to 75,000 volts for this early engine) - high enough to jump the gaps between the rotor and the distributor cap terminals, and the electrodes at the base of the spark plug..... Assuming that the engine is properly timed, the spark reaches the air-fuel mixture in the cylinder and combustion begins....

 

As the distributor continues to rotate, electrical contact between the rotor and distributor cap terminal is broken, stopping the secondary high voltage flow.... At the same time, the breaker points will close to re establish the primary low-voltage circuit, allowing primary current (12 volts) to flow. This primary current will again create a magnetic field in the coil primary windings and the cycle is repeated for the next cylinder in the firing order.....

 

This process takes place within a few milliseconds. In fact, it happens approximately 18,000 times per minute at 90 miles per hour.

 

There is no "Condenser Coil", the condenser and coil are two distinct different parts of the system..... The condenser on your bike engine is that little silver cylinder mounted to the side of the distributor.... The condenser is not hidden, the ignition coil is...

 

Not criticizing here, just offering the correct understanding of what the equipment is supposed to be and how it works...

 

EG

Edited June 6 by Egilman

[DocRob]

15 hours ago, Egilman said:

I think a bit of explanation is needed here... All ICE's (internal combustion engines) manufactured today use electronic breakerless ignition controlled by the vehicle's CPU... Going back about 50 years the standard was a coil ignition and the Breaker function was provided by solid state components in an electronic module to provide the magnetic field collapse needed to fire the plugs...

 

Prior to that the standard was breaker point ignition which had been around since the early 1900's... The breaker point system consists of a set of Breaker Points, a Condenser, (capacitor) and a Dual Windings coil... (a voltage step up coil)

A breaker point ignition system has two circuits a primary (energizing) and secondary (discharging) circuit and how it works is simple....

 

The primary circuit carries low voltage... (12 volts) This circuit operates only on battery current and is controlled by the breaker points and the ignition switch.... When the ignition key is turned on, a low voltage current from the battery flows through the primary windings of the ignition coil, through the breaker points and back to the battery... (to ground) This current flow causes a magnetic field to form around the primary coil....

 

The secondary circuit consists of the secondary windings in the coil, the high tension lead between the distributor and the coil (commonly called the coil wire) on external coil distributors, the distributor cap, the distributor rotor, the spark plug leads and the spark plugs.... As the engine rotates, a cam on the distributor shaft turns until the high point on the cam causes the breaker points to separate suddenly.... Instantaneously, when the points open (separate) current stops flowing through the primary windings of the ignition coil.... This causes the magnetic field in the coil to collapse around the coil. The condenser (capacitor) absorbs and stores the energy to prevent arcing between the points each time they open. By sucking up all this energy the condenser speeds up the rapid collapse of the magnetic field.....

 

The line of flux in the magnetic field, (hi magnetic potential to low potential) cuts through the secondary windings of the ignition coil, creating a very high voltage (50 to 75,000 volts for this early engine) - high enough to jump the gaps between the rotor and the distributor cap terminals, and the electrodes at the base of the spark plug..... Assuming that the engine is properly timed, the spark reaches the air-fuel mixture in the cylinder and combustion begins....

 

As the distributor continues to rotate, electrical contact between the rotor and distributor cap terminal is broken, stopping the secondary high voltage flow.... At the same time, the breaker points will close to re establish the primary low-voltage circuit, allowing primary current (12 volts) to flow. This primary current will again create a magnetic field in the coil primary windings and the cycle is repeated for the next cylinder in the firing order.....

 

This process takes place within a few milliseconds. In fact, it happens approximately 18,000 times per minute at 90 miles per hour.

 

There is no "Condenser Coil", the condenser and coil are two distinct different parts of the system..... The condenser on your bike engine is that little silver cylinder mounted to the side of the distributor.... The condenser is not hidden, the ignition coil is...

 

Not criticizing here, just offering the correct understanding of what the equipment is supposed to be and how it works...

 

Wow thank you Egilman, I can feel your head shaking about my non existent knowledge about the ignition system of classic bikes. I will need some time to digest the thorough information you supplied here. I have to understand the English terminology first an then the described process itself.

Cheers Rob

[Egilman]

Thanks Rob... I"m a big believer in knowing from whence we came... Understanding these things helps us keep perspectives on life... The internal combustion engine is one of those inventions that was world changing... Prior to that, everything was work for you or your animals... Afterwards all we needed was a tool to do the work for us... Today very few understand that the car or motorcycle is more than a hop in it and turn the key... As a kid we used to walk to the corner store, walk to school, walk to work... Today no one goes anywhere without turning a key, not even to go around the block...

 

And in modeling, we keep the technological history of man alive.... If we are willing to learn the lessons of it....

 

Give me a lever and I'll move the world, the wheel is a rotational lever, an eccentric wheel combined with a lever gives us back and forth motion as long as the wheel turns.... Everything builds upon that which came before, if we lose sight of that we lose our understanding of what we as a specie went through to get where we are, then we lose ourselves....

 

Your doing a wonderful job on this kit Brother... And enough of my philosophical ramblings...

 

{chuckle} 

 

Model on my friend...

[Jack12477]

1 hour ago, Egilman said:

Today no one goes anywhere without turning a key,

Ahem! Don't you mean pushes a button while carrying a RFID chip fob in their pocket! 😉😉😊😇

 

All we do now is wave our hand and the doors unlock or the trunk lid/tailgate opens magically. 🤔 Open Sesame !!

Edited June 7 by Jack12477

[CDW]

3 hours ago, Jack12477 said:

Ahem! Don't you mean pushes a button while carrying a RFID chip fob in their pocket! 😉😉😊😇

 

All we do now is wave our hand and the doors unlock or the trunk lid/tailgate opens magically. 🤔 Open Sesame !!

I had to laugh...at one of our recent family reunions, my wife and sister-in-law were admiring the sporty Tesla someone had parked on the grounds. When their hand came near the door handle, it magically popped out and scared my wife half to death. She thought she had done something wrong 😄

[DocRob]

15 hours ago, Egilman said:

Thanks Rob... I"m a big believer in knowing from whence we came... Understanding these things helps us keep perspectives on life... The internal combustion engine is one of those inventions that was world changing... Prior to that, everything was work for you or your animals... Afterwards all we needed was a tool to do the work for us... Today very few understand that the car or motorcycle is more than a hop in it and turn the key... As a kid we used to walk to the corner store, walk to school, walk to work... Today no one goes anywhere without turning a key, not even to go around the block...

 

And in modeling, we keep the technological history of man alive.... If we are willing to learn the lessons of it....

 

Give me a lever and I'll move the world, the wheel is a rotational lever, an eccentric wheel combined with a lever gives us back and forth motion as long as the wheel turns.... Everything builds upon that which came before, if we lose sight of that we lose our understanding of what we as a specie went through to get where we are, then we lose ourselves....

 

Your doing a wonderful job on this kit Brother... And enough of my philosophical ramblings...

 

{chuckle} 

 

Model on my friend...

Luckily my world doesn´t only move by turning a key or push a button, as I walk, run, work in the garden and bike a lot without burning fuel or electricity. No blocks where I live .
You´re right, technology, specially combustion engines changed the world, but computers and smartphones also did. Do you have the same technological insight on these evenly important modern world movers? Me neither and I don´t want to sound disrespectful. What I mean, technology changes and in it´s whole is very complex to understand. I´m a bit more than half wit with computers, but with combustion engines, it´s only very basic knowledge, I possess, even when I studied engineering in the late 80´s.
When I got my apprenticeship as an engineer, I built a steam machine from raw material as a learning project and there are not many mysteries with these anymore. We also developed a CNC-milling machine as a project, late 80´s, like I said and that left a thorough insight, which was reinforced later on. With car and bike engines, it´s different, I´m more of a user. I understand nearly all the mechanical processes, but fail where electricity comes into the game.
Modeling is clearly a chance to understand technology, due to replicating them and discuss the subjects, like here on MSW. I learned a lot about the "how does it work" through modeling, but it takes time with complex knowledge. The Crocker is a good example, where there is a lot of technology involved, with only little more, like design. In a way, it´s technologic essence, nearly nothing is hidden and therefore prone for learning.
I can only thank you again for showing me, how this wonderful bike works.

Cheers Rob 


 

[Egilman]

Amen Brother....

 

 

[DocRob]

The battery/alternator area was a little bit nightmarish to assemble, with lots of connecting parts, PE brackets and the wiring, which needed to be pre fabricated, because of the tiny PE connection fittings. Somehow, I got it done with a bit of wiggling. 
Adding the pedals on both sides was much simpler affair, luckily and they are now awaiting the footrests.
Until now, there is one thing to remember with that kind of build. Study the manual, examine, where all the parts connect and how, measure the connecting diameters and drill out the corresponding holes and try not to forget any, as they may be impossible too reach later. Sure, test fitting is mandatory as well.


 

Cheers Rob

[CDW]

Outstanding!

[DocRob]

Lots of prep work done lately. I filed, sanded and near polished fuel tank and mudguards, primed them with Mr. Color grey primer 1200 and sprayed the tank with Tamiya LP-2 gloss white, which came out nice and shiny. Of course, I drilled all the necessary holes beforehand.


 

The rims also needed a lot of preparation. As you can see on the pic, there are prominent cast seams between the spokes, which I cleaned with a sharp blade and then used a rotating tool to refine the surfaces. I decided against polishing and also primed the rims, after I drilled the holes for the spokes. 
Body color will be black now, where initially thought about dark blue, but I don´t like the look of blue rims.
All other parts, which will be painted black, were drilled, prepared and primed.



Luckily some help arrived today, more drill bits and two DSPIAE hand drills, the left one with a collet, the right one with a chuck. You can´t have enough of these, as you permanent need to drill holes in different diameters.



Cheers Rob

[Egilman]

{chuckle} "He who has the most tools wins!!!"

[CDW]

3 hours ago, Egilman said:

{chuckle} "He who has the most tools wins!!!"

He who has the most tools spends the most time looking for where they left the tool when they finished using it last. That's my story and I'm sticking to it. 

[DocRob]

Hmmh, well, mixed success for today. The decals for this MFH kit are extremely well made. They fit perfectly, are robust and have a good color density. I dreaded the golden pinstripes on the mudguards a bit, but they came out great, applied only with water and a drop of detergent, no decal solutions needed. The parts are still not gloss coated.


 

I´m not happy with the fuel tank. As per manual, I airbrushed it gloss white, masked off the front part, and sprayed the rest gloss black. The finish was almost perfect, but there was a tiny parting line between the colors. After applying the decals, the parting line showed even more, but there is also a different hue to the white sprayed part of the tank. I may strip the tank and use other decals as decor. The flame decals generally lay down beautifully and all the wrinkles on the curved contour could be pushed out while curing, but the result is not satisfactory. I watched the MFH promotion pictures of the kit, and the parting line is visible as well, bummer.



Cheers Rob

[DocRob]

I gave the fuel tank another try and oversprayed the white, after sanding away the visible seam, using a different white color. The result was better but not good enough, so I stripped the tank, something I never did before. I always try to have the perfect plan, the appropriate tools, but this time, no luck.

There are several decals for the fuel tank included in the kit, so my next try will be a polished finish with next to apply pinstripes in flame shape, similar to the black and white design.
I filed and steel wooled the surface, before I polished with Autosol and my Proxxon cotton bit and finally by hand with cotton cloth and again Autosol.

Somehow the sheen is hard to capture, it looks near mirror like in reality and the grey ´smear´ on the lower pic is some kind of reflex , no bad spot.





Cheers Rob

[CDW]

Can you use the decal as a template to cut your own masks? Then, just paint the two tones and forget about the decals. Just a thought...

[DocRob]

8 hours ago, CDW said:

Can you use the decal as a template to cut your own masks? Then, just paint the two tones and forget about the decals. Just a thought...

I thought about that too, Craig, but cutting the masks error free, without a cutting plotter would surely exceed my abilities. I always had the fall back plan to do a polished version of the tank with decaled flame contour ornament. The last option, would be a part black, part polished fuel tank.

Cheers Rob

[DocRob]

That´s how the Crocker looks with the applied flame contour decals. I added the rear fender loosely to get an idea how everything looks, before I start to clearcoat everything.









there is also another option included, which includes decals the front part of the tank to be pre painted gloss black. Looks attractive too, but somehow, I like the polished finish.



Cheers Rob

[gsdpic]

Looks good.  Unfortunate that you had the little detour but I, for one, like the polished tank with pinstripes better than the original black and white.

 

[DocRob]

4 hours ago, gsdpic said:

Looks good.  Unfortunate that you had the little detour but I, for one, like the polished tank with pinstripes better than the original black and white.

Thank you Gary, polishing the tank was always the second option, if the two color scheme failed and I doubted a positive outcome from the beginning. I start to like the finish and today, I sealed everything under a layer of gloss coat. When do you have the chance in modeling to let metal look like real metal, no Alclad no Extreme Metals, just the real thing.

Cheers Rob

[DocRob]

Gloss coating to me is always adventurous and this time was not different. I used Mr. Color GX-100 clear gloss, which really looks perfect, when everything fits, but can be a nightmare to work with. I had cases in the past, where I had an effect like cotton candy, when spraying the GX-100 and thought, it was, because the clear was contaminated during the process.

This time, I picked a new jar of GX-100, opened a new bottle of Mr. Color leveling thinner, poured both liquids directly into the metal cup of my airbrush and stirred with a cleaned metal rod. The airbrush was thoroughly cleaned beforehand. 
Cotton Candy again on my test sprue. As the whole process was clean and uncontaminated, I added more thinner, step by step and finally, it worked. The mix was not too thick at the beginning, but seemed to be the reason for that strange effect.
I would really like to master that stuff on a reliable basis and take the thrill out of this step.

Cheers Rob

[CDW]

50 minutes ago, DocRob said:

Gloss coating to me is always adventurous and this time was not different. I used Mr. Color GX-100 clear gloss, which really looks perfect, when everything fits, but can be a nightmare to work with. I had cases in the past, where I had an effect like cotton candy, when spraying the GX-100 and thought, it was, because the clear was contaminated during the process.

This time, I picked a new jar of GX-100, opened a new bottle of Mr. Color leveling thinner, poured both liquids directly into the metal cup of my airbrush and stirred with a cleaned metal rod. The airbrush was thoroughly cleaned beforehand. 
Cotton Candy again on my test sprue. As the whole process was clean and uncontaminated, I added more thinner, step by step and finally, it worked. The mix was not too thick at the beginning, but seemed to be the reason for that strange effect.
I would really like to master that stuff on a reliable basis and take the thrill out of this step.

Cheers Rob

That cotton candy effect is from not enough thinner. Instead of 50-50, you need about 1 part clear to 3 parts leveling thinner. I just experienced the exact same thing today while clear coating this car body with Super Clear II. The good news is, if you apply the more highly reduced clear paint, it will clear that cotton candy up just like magic.

[Egilman]

I was going to mention being sprayed too thick, but Craig got to it first... Mine has always been 4-1 mix when using heavy bodied clear coats, the consistency of running water, even wet coats as thin as possible... Leveling thinner makes it a bit less critical on the mix coats....

[DocRob]

13 hours ago, CDW said:

That cotton candy effect is from not enough thinner. Instead of 50-50, you need about 1 part clear to 3 parts leveling thinner. I just experienced the exact same thing today while clear coating this car body with Super Clear II. The good news is, if you apply the more highly reduced clear paint, it will clear that cotton candy up just like magic.

 

 

12 hours ago, Egilman said:

I was going to mention being sprayed too thick, but Craig got to it first... Mine has always been 4-1 mix when using heavy bodied clear coats, the consistency of running water, even wet coats as thin as possible... Leveling thinner makes it a bit less critical on the mix coats....

Thank you Craig and Egilman, it confirms, what I started to understand with the clear coat. I began with an approximately 60/40 mix, where the cotton candy effect started and then thinned a bit more and the effect vanished. 60/40 is my go to mixing ratio for lacquers and similar and works perfectly with my usual colors and relatively low pressure setting. More thinner would lead to not enough color coverage and possible color running.
Clear seems to be a different breed and I was confused about past results, where I thought, contamination was the problem. Luckily, I try colors on a dummy sprue first, as not all the cotton candy residues vanished with overcoating. Tiny white residues where left, not acceptable for me.

Cheers Rob