HONDA CB750 Four K0 by yvesvidal - TAMIYA 1/6 and MPC 1/8

[yvesvidal]

Folks,

 

This is a crazy idea, but I have to try it: Build two models of the same Vehicle, but at different scales. I have also decided to not build another war machine (for the time being) as the planet absolutely needs a wind of peace, harmony and balance. 

 

I am a fanatic about Motorcycles and started riding at the age of 13 years old (legal age in France was 14) using mopeds from friends. At the age of 14, I got my first little motorcycle, a DERBI 50 cc with a gearbox with 3 speeds controlled by the foot. The gear patterns were reversed from the Japanese motorcycles and what was to become the standard, but the idea was there. I still have that DERBI bike and moved to a Suzuki 125 GT, at the age of 17. All my youth was spent admiring these big machines such as HONDA CB750, CB550K, LAVERDA, Moto Guzzi V7, Suzuki and other Kawazaki Mach 2 and 3 (the widowmakers) and smaller motorcycles such as the Yamaha, Honda CB125 K4 and many more. A large chunk of my life would then be spent without owning any motorcycle but the urge was always there. In 2001, I purchased a BMW R1100S that I still have today and ride occasionally (that model was never reproduced in scale model, unfortunately).

 

One of my favorite bikes and one that truly revolutionized the world of motorcycles, was the HONDA CB750 Four introduced in 1969 to the world. Much has been said about this bike but I never had a chance to ride it, unfortunately. I did ride the CB 550K and the CBX 1000 with six cylinders in line, though. These were two incredible bikes, especially the CBX with its fantastic power, speed and accelerations.

When the CB750 Four K0 came out, it was immediately embraced as a cult bike and many famous people in Europe (and elsewhere) were seen riding it. Here is an example of French singer Francoise Hardy, riding her CB750 in the streets of Paris: 

Back to the scale models, after this brief introduction of the fantastic HONDA CB750 Four.

 

I built the HELLER Honda CB750 (1/8) in 1971 when that model came up on the French market. I was not even a teenager at that point and my passion for motorcycles was already intense. HELLER was proposing a large choice of models, all in the scale of 1/8: Nortons, BMW, Laverda, Honda, Kawazaki, Yamaha and a few others.

 

The HELLER model was fantastic and very realistic and seems different from the MPC model that I will be trying to build. I compared the sprues of the HELLER and the MPC kits, and they are vastly different although at the same scale.

 

First the TAMIYA kit at 1/6th, which is a classic and has been available for a very long time: 

The kit I bought on E-Bay long time ago, is very old and the decals are damaged due to their ages. All the other parts (rubber mostly) are still in very good shape and flexible. I contacted TAMIYA USA who offered to sell me another set of decals as soon as the stupid confinement is over.

For the scale of 1/8, I could not get an HELLER kit at a decent price and thus fell back on the MPC kit. Both Tamiya and MPC are depicting the original K0 version of the CB750, with its sleek air box and its lack of the small lights dashboard, available on later model K1 to K4 as well as the later CB 550K bike. 

As indicated before, I am going to try to build the two kits at the same time. I have never done that before and I honestly think it is crazy. However, it will be interesting to compare the excellent and extremely detailed Tamiya kit with the more common and affordable MPC kit and appreciate the different sizes of the parts and sub-assemblies.

 

Progress will be slow as I still have to finish my submarine.

 

Yves

 

 

 

[kpnuts]

I'm in.

[MadManSK]

Nice idea.. I drive on motorbikes from my 10 years. Before only motorbikes made in Czechoslovakia, like JAWA and CZ.. Later first Japan m.b. HONDA VF 750F (nice too) and finally I am driving on Honda CBR XX Superblackbird.
I will folow your new build. I am looking forward.

 

[yvesvidal]

And the craziness starts.... 

 

On the Tamiya kit, the wheels are very nicely molded, but these spokes chrome plated and touching each others, are not exactly realistic. So, I jumped in and decided to replace all the plastic spokes with insect pins. I purchased the larger size (#5) which at the scale of 1/6 are very close to the diameter of the prototype spokes. It is a very tedious job and I am replacing one spoke at a time, to keep the wheels round and concentric. The pins I have are of the perfect length and once bent, fit without any additional cutting.... a bit of luck. The end result is not too bad and you can compare the kit wheel and the reworked wheel: 

I did not install the small brass pieces used to adjust the tension of the spokes. I could not find any tube or insulating material small enough to do a good job. In addition, the color would probably not match and the size of these parts is really so tiny that I decided to skip them, completely.

The difference in rigidity of the wheel flange is amazing. Where the plastic flange can be bent easily, the metal spokes are very sturdy and solid.

Here you can compare how the spokes are behaving: quite a contrast!! Plastic above, stainless steel below: 

Other side, showing how this is all put together: 

The idea of re-wiring (or re-spoking) the wheels came from what I consider to be the best motorcycles kits builder in the world: Kinishi Karube.  His site can be reached at: http://kimshouse7015.com/

 

Yves

 

[popeye the sailor]

nice start yves......looks really good!

[Egilman]

I"m here

 

[kpnuts]

Omg that's detail I would never undertake (I replaced the spokes on a 1/12 Bentley and swore I would never do it again, admittedly that was 5 wheels)

A great start.

[Egilman]

16 minutes ago, kpnuts said:

I replaced the spokes on a 1/12 Bentley and swore I would never do it again

it's a bit easier at twice the size......

 

[yvesvidal]

Yes, it is a bit easier but I am glad I finished the front wheel. Once you get the pace, it goes relatively smoothly. The trick is to be organized and to do one spoke at a time.

For the MPC model at 1/8, I did not replace the spokes.... I do not know how this Japanese Kinishi Karube does it, but I am not able (or willing) to spend so much time perfecting a plastic scale model. 

 

So, here is the process:

 

Both sides done, all chrome paint removed, ready for gluing: 

Details of the insect pins used for that model: 

Gluing phase. You need a lot of clamps, as there is a tremendous pressure for both sides of the wheel to split: Plastic glue with a layer of CA glue to secure the whole thing. Let it dry for a few hours.

Ready for mounting the tire: 

And the front wheels finished: the MPC model is  a lot easier to put together....

Re-spoking is a lot of work, but I believe that the end  result is worth it. Notice the difference of tires: Tamiya has Bridgestone whereas MPC proposes Good Year. Tamiya tire is 3.25 x 19 and MPC tire is 3.75 x 19. Slightly wider on MPC and their "9" looks like a "0".

 

Yves

 

 

Edited May 7, 2020 by yvesvidal

[Old Collingwood]

45 minutes ago, yvesvidal said:

Yes, it is a bit easier but I am glad I finished the front wheel. Once you get the pace, it goes relatively smoothly. The trick is to be organized and to do one spoke at a time.

For the MPC model at 1/8, I did not replace the spokes.... I do not know how this Japanese Kinishi Karube does it, but I am not able (or willing) to spend so much time perfecting a plastic scale model. 

 

So, here is the process:

 

Both sides done, all chrome paint removed, ready for gluing: 

Details of the insect pins used for that model: 

Gluing phase. You need a lot of clamps, as there is a tremendous pressure for both sides of the wheel to split: Plastic glue with a layer of CA glue to secure the whole thing. Let it dry for a few hours.

Ready for mounting the tire: 

And the front wheels finished: the MPC model is  a lot easier to put together....

Re-spoking is a lot of work, but I believe that the end  result is worth it. Notice the difference of tires: Tamiya has Bridgestone whereas MPC proposes Good Year. Tamiya tire is 3.25 x 19 and MPC tire is 3.75 x 19. Slightly wider on MPC and their "9" looks like a "0".

 

Yves

 

 

I've laced and tuned  cycle wheels  but never a motorcycle.

 

OC.

[popeye the sailor]

little too insane for my blood........looks good though.

[mtaylor]

The lace wheels are amazing.  

[Old Collingwood]

14 minutes ago, mtaylor said:

The lace wheels are amazing.  

Quite an artform for lacing and tuning a wheel   using a rig  with center blocks you position each side with the wheel  center  centtered, then you turn the nipple on each spoke increasing or decreasing the tention pulling/releasing the rim till it dead center between the block, you do this all around the rim till its true.   (I used to build repair bicyles for a living years ago)

 

OC.

 

 

Edited May 8, 2020 by Old Collingwood

[CDW]

Great project Yves. Those wheels are gorgeous! 

In 1972, I rebuilt this 450 Honda. The 450 was a huge step up from the CB350, the dual overhead cams made a big difference. Standing beside me is my older brother who helped me with the project. He and I were both motorcycle fanatics.

 

[kpnuts]

Looks great yves but still something I will never try again.

[popeye the sailor]

you can't help but notice the size difference between 1:6 and 1:8......

[Old Collingwood]

1 minute ago, kpnuts said:

I would have loved to put them with the enormous 1/4 ducati but I had already sold the 1/6 honda and Suzuki on ebay for the princely sum of £3.50

"What  - made"    that was bad   your workmanship deserves far more  than that.

 

OC.

[kpnuts]

I was annoyed that was both of them for 3.50 I said when the bloke came to collect them I would rather have set fire to them. He did say sorry I didn't think I would get them for that.

Anyway I dont want to hijack Yves post I just thought I would show the size difference.

Edited May 8, 2020 by kpnuts

[yvesvidal]

Let's move to the chassis of both bikes. Here again, Tamiya presents a fabulous chassis with a  great assembly, similar to the real one. We are just missing the soldering rods and the torch.

MPC on the other hand is really simplified, even for a 1/8 scale model. You can tell that the kit is old, was never re-tooled and as far as I can remember, the HELLER kit was more detailed and close to reality.

 

First the rear arm: exquisite of details on the Tamiya model, with adjustable wheel holders and soldering lips. MPC, on the other hand, ultra simplified and vaguely correct.

The main frame: 

There is a lot of work to finish up the frames with putty and fine sanding to make these tubes round. Not so bad on the Tamiya, but the MPC will require some TLC. Fortunately, I have that new Acrylic Putty (Vallejo) recommended by CDW. It is going to come handy, here.

 

On the Tamiya kit, everything is replicated with exquisite details: look at these solder marks..... It is just amazing for a kit created in 1971.

Yves

[kpnuts]

Yes the tamiya kits are beautifully made I love them.

[kpnuts]

I actually have the heller kit and started it (will have to dig it out maybe we could compare that one to the mpc one, I know it's still not in the same ball park as the tamiya kits)

[kpnuts]

I just checked on scalemates and the heller version is a rebox of the mpc one so it's the same kit.

[yvesvidal]

17 hours ago, kpnuts said:

I just checked on scalemates and the heller version is a rebox of the mpc one so it's the same kit.

Scalemates is completely wrong on this one. Below are two pictures taken from the Super-Hobby site, depicting the Heller kit. You can see that the Heller kit is built like the Tamiya kit, whereas the MPC takes a lot of liberties with the accuracy. Just compare the Heller sprues with the previous pictures I posted before. I still believe the Heller kit is vastly superior: 

Yves

Edited May 10, 2020 by yvesvidal

[yvesvidal]

Both frames have been puttied (to a certain extent) and tubes filed to make them look like round steel tubes. Finally, everything is primed in light gray, with automotive primer.

Below is a picture of the real frame from a HONDA CB750 1974. The picture is from a famous Auction site, someone selling a complete frame: 

The main thing that jumps to your attention are the two re-enforcement bars located under the fuel tank. These are missing from both kits. However, they do exist on the HELLER kit (see previous post).

 

Below is the frame, from the HONDA spare parts manual. Most likely, this is a newer frame, possibly found on the latest CB750 Four models (1974 and newer).

 

On the MPC kit, it is not possible to add them as the underside shell of the fuel cell, matches very closely the tubular upper spine of the frame.

 

On the Tamiya kit, it could be done as the fuel cell matches the real tank and allows for these bars to be installed. However, I think that if Tamiya did not depict them, it is because they have modeled the 1969-70 early model of the CB750, which probably did not have these two bars. I suspect these bars were added later on, to increase the stiffness of the frame and the road handling.

 

My understanding is that the Tamiya kit depicts the early CB750, as is proven by the ignition system of the kit. The MPC kit having been issued in 1971, may also have taken the same approach.

 

Simple regret on the Tamiya kit: I wish they had stamped the CB750 Serial number on the collar of the front fork. It is something that could be done by hand and would be visible, once the model is completed.

 

Yves

 

 

Edited May 11, 2020 by yvesvidal

[yvesvidal]

Moving along to the front fork. Tamiya fork presents some kind of suspension, whereas MPC is solid. The instructions: 

Working suspension for Tamiya, a lot more simplistic for MPC: 

Tamiya uses a nice brass tubes arrangement and two springs to offer about 5-6 mm of travelling: 

MPC did cast the fork with Chrome plating, which needs to be removed, as there is no chrome on the fork of a CB750: 

All the parts are soaked in that Super Clean degreaser suggested by CDW and Egilman, and after 6 hours, the parts are turned to their original black molding. Other parts only took a few minutes, after setting them in my warmed ultrasound cleaner..... Somehow, the plating on the fork sprue seems to be very thick.

 

Sizes and complexity comparison: 

Finally, forks have been glued, sanded, painted with Tamiya flat aluminum: 

To complete this part of the assembly, here is the Honda Manual page on the fork and a picture of a real Honda CB750 fork: 

You can see how the Tamiya rendering of that part is so exquisite.

 

Yves

 

 

Edited May 14, 2020 by yvesvidal

[kpnuts]

Nice work and comparison.

[MadManSK]

Yves work is always smart and a pleasure to watch 🙂

 

Width between two tires half an inch its interesant...

 

tamiya model looking better, of course, it is about scale... better scale, more details...

 

Jan. MMSk

 

[yvesvidal]

Frames have been painted with Tamiya Black X-1: 

Yves

[yvesvidal]

Due to some security firewall issue with this web site, I have lost an entire and comprehensive update on the MPC kit. Therefore, I will only post a few pictures and give some brief explanations (I hate to do things twice).

 

The MPC engine parts were de-chromed in a few minutes, using a warmed ultrasonic cleaner with Super Clean. Parts were assembled, primed and painted Tamiya flat aluminum. Sorry for being so brief, but everything was clearly documented with a galore of pictures in the lost post.

 

The engine was then inserted into the frame and glued in place: 

And finally, the rear shock were installed, locking the rear wheel holder in place: 

I have looked at quite a few pictures of HONDA CB750 of the early days. The engine has very few chrome parts and I have only kept that cover, with the original chrome plating.

I think that most of the time, it is aluminum highly polished: 

 

Now, I need to catch up with the Tamiya kit.....

 

Yves

Edited May 15, 2020 by yvesvidal

[MadManSK]

Pfuuuu.. this engines looking realy good 

 

Jan.

 

Edited May 15, 2020 by MadManSK