Miyata Assembly - Why Hello There!

It speaks!

Thanks to a new petcock from Treatland and a new 12v battery from Pep Boys, the Miyata started right up and ran great. I didn't even need to adjust the idle or idle mixture. The petcock uses a M16x1.0 bung, and luckily some Puch mopeds and Ducatis use this size. It threaded on like a champ, and thanks to a glass fuel bowl in the bottom, it is easy to see fuel flowing.

Now I get to turn my attention to all the little details, like getting some chrome re-finished, making a rear taillight, finding some rear turn signals, and new Miyata script logos for the side covers and handlebars. All the fun stuff.

Miyata Assembly - More Stuff

I got a couple small things installed, mostly just to see how it looks. Including the side covers:

I was originally thinking the bike would have too much green, and maybe the side covers should be a different color, like vanilla or cream. But I kinda like it like this, and it will get better with the "Miyata" script logos on the side covers:

In preparation of it running, I threw on the exhaust system. All the chrome on it was heavily pitted, so I'm trying to decide what to do with it. I found a chrome shop in Yuba City, so I might pay them a visit with the full exhaust and the headlight chrome ring.

Miyata Assembly - Seat and Footpegs

I found a set of footpeg rubbers for a Yamaha YSD1 with a very similar pattern to the original Miyata units:

I also got the original seat pan and foam built back up. It took a few tries, but the original seat covers seems to fit:

It is a little bit lumpy on the side, but I think it will smooth over as it stretches out over the new foam. I was able to really scrub the old grim off the vinyl and it looks pretty good:

Miyata Assembly - Wiring

Short story made super boring...I got both spark on the Miyata, and an electric starter that turns the engine over. I realize that sounds normal, but considering I have no wiring diagrams, and that some of the wiring was disconnected when I got it, I'm amazed I got it on the first try.

As luck would have it, the big red wire from the key connects to the red wire on the main harness, which then connects to the starter relay and coil output. So my first try, it made the sparkies and the button on the right handlebar activates the starter. It is strange having an electric starter on a bike. My thirteeen other little dinks just have a kick starter.

I just need a 12v battery that fits in the battery tray. And then I guess I can put some fuel in the tank, mount up the exhaust, and maybe it will run?

Miyata Assembly

What a better way to spend a near 70 degree day, than to do some assembly on the Miyata. I managed to get it into a roller pretty quickly.

Installing the rear wheel assembly:

front and rear suspension and wheels installed. A roller!

I also planned ahead and got the main wiring harness run through all of its little tangs (that keep it secure):

After lunch, I installed the handlebar and controls, some of the cables, the luggage rack, and finally the engine:

Starting to look like a bike!

Miyata Details - Paint and Wheels

I took advantage of the good weather we've been having lately, and got a bunch of the Miyata parts painted. That means I might be able to do some assembly this weekend! Which is always the fun part.

But before that, I managed to get the bastard wheels fully assembled. Bastard, because as mentioned before, the Miyata used a bicycle size wheel and tire. I wouldn't be able to reuse the original wheel rims because the chrome was knackered. I had a spare set of good 17" rims, and ordered a set of shorter 184mm wheel spokes from the land of Bangkok. It all managed to come together quite nicely, after an evening of lacing.

C'

Miyata Details - Stripping and Cleaning

I've spent the past week doing all the dirty work, cleaning up old grungy parts and stripping paint. My least favorite activity in a restoration project. But I've made good progress, especially yesterday and today.

The hardest part to strip was the frame. Lots of little nooks and crannies to get into:

By comparison, the engine cleaned up nicely. I pulled both the magneto side and clutch side covers off, so I could clean them inside and out. I decided not to take off the cylinder, since it looked so good. I did, however take off the cylinder head and decarbonize the combustion chamber.

Chris H.

Miyata Details - Wheels/Tires

As if some of the details on this Miyata weren't weird enough, guess what I discovered when I started tearing down the wheels? It doesn't use a conventional 17" or 18" motorcycle wheel/tire. It uses some strange 1960 bicycle style setup. The tire and tube are marked "22x2.25" and the tire has a protruding lip that fits into a corresponding groove in the wheel mounting surface.

Proof:

So here is the problem. The original wheel rims are horribly pitted chrome. Also the tires look to be originals, and are dry cracked. I was assuming I could replace the rims with new/spare 17" rims like used on the Honda Cubs I have so many of. Or the 18" rims from the Honda S90s I have. Not quite. The stock rims measure somewhere in between a 17" and 18" rim.

That means the wheel spoke length won't be ideal. too short for 18" rims, too long for 17" rims. I could cut about 1/4" off the spokes, but the threads won't be deep enough. So I would need to re-thread 72 spokes. And I'm sure it is a very small, fine thread that I might not have a die for.

But the land of Bangkok came to my rescue. When I ordered new spokes for the Kawasaki project, I noticed some vendors offered generic spokes in different lengths. So maybe I could get a set of spokes that were longer or shorter, without paying a custom spoke shop to make me new ones at $3 a spoke.

The stock spokes measure roughly 192mm long. I found the same joint that I got the Kawi spokes from have 184mm sets, with brand new nipples. I did some measuring, and it looks like these will work just dandy in conjunction with the 17" wheel rims. Which is great, because I have two very nice 17" rims, two 17" tubes and rim strips. All I need are two new tires.

So I spent the afternoon stripping down the stock wheel assemblies so I can clean up the hubs. And I'll place an order for my new spokes once I get a full price for two sets with shipping from the land of Bangkok.

Hopefully this grand plan works.

Miyata Details - Ignition

Interesting ignition/stator/coil setup on this beast. The stator is pretty typical, with the points and condenser mounted to the plate. What is somewhat unique, is the fact the points cam isn't attached the inside of a flywheel In fact, it seems to be on the end of the crank snout.

Points look brand spanking new, as does the condenser:

On all of my other bikes, a flywheel is bolted on the end of the crank, and rotates around the coils. Usually the inside of the flywheel has a cam that the points run off of. In this case, there doesn't seem to be a flywheel. And the combined coil and starter run inside the magnets, which are attached to a stationary drum:

Miyata Details - Seat

I very carefully pulled apart the seat on the Miyata. The seat pan is in very good shape, just a little dirty. The foam is a strange combo of three different types of rubber, foam, and a topping that feels like soft wall insulation. The whole thing is lumpy and bumpy, and will need a total redo. The upholstered cover is actually in pretty good shape, with only one small tear. I might try to fix that and keep the cover original.

It looks rusty, but the seat pan is mostly just covered with dried up seat foam:

Miyata Details - Exhaust

This is one of the parts on the Miyata that is quit a bit different than any of the other bikes I have. The header pipe is conventional, but the main exhaust expansion chamber has a mount built into it, and a silencer. The rear part of the expansion chamber actually fits over the end, and is secured with a nut that attaches to the long threaded rod sticking through the middle.

Main diameter is 1", then expands to 2.75".

Miyata Details - Shocks/Forks

I've been disassembling some of the smaller items on the Miyata, including the rear shocks and front fork assembly.

Rear shock assembly town down. Notice the gray plastic spacer that sits under the spring:

Front fork uses leading links, with small shock/spring combos. Very similar to the early Honda leading link setups:

Both front and rear setups laid out:

Chris H.

Amal 392 Detail Photos

As the title suggests, some detail shots of the Amal. The throttle valve is 16mm in diameter:

Miyata Details 1

I couldn't help myself. I wanted to see the condition of the top end on the Miyata Engine. It turns over very nicely, so I knew it wasn't frozen up. As it happens, the cylinder looks fantastic. Very clean bore, no scoring at all. And since I don't have any specs, I was curious what type of carb it runs, and what spark plug. Of course the spark plug has likely been changed, and who knows if it is the correct one. But at least I know the thread pitch and reach are correct.

Interesting combustion chamber shape, with offset plug location:

Amal carb? Really? An Amal 392 to be specific. I'll have to research this monster to see how big it is. PS: I don't have big hands, so you can compare the size of the inlet to my thumb in this pic:

BTW, the spark plug was a Champion L90C. Which corresponds to a NGK B4H.

Edit: For Sean and Mr. A:

I did some google searching on the Amal 392. I found this posted on the VJMC list:

"To help aid in identifying what might have used this 392 Amal I have posted

photos and they are in the 7th group on first page. 20mm bore on mounting
flange with a bolt spacing of 38mm. Thanks for your interest and help.

Wally Skirman"

Miyata Teardown Deuces

I spent about an hour this morning finishing the teardown on the Miyata. It went pretty smoothly, as everything had enough oil and grunge on it to not be rusted. It was also interesting to see how different this bike is put together. Completely different way of mounting parts, more and different types of fasteners etc.

End Result:

Edit: I weighed a few of the major parts, just for shits:

Frame: 23#

Engine: 30#

Front Wheel: 12#

Rear Wheel: 13#

Front Fork Assembly: 10#

Swingarm: 5#

Exhaust: 2#

Miyata Teardown 1

I cleaned up the garage a bit, and got the Miyata Miyapeto into the forefront, for a bit of teardown.

Handlebars off:

Main electrical junction. Despite the early 1961 vintage, the Miyata is both 12 volts and features an electric starter:

Seat off:

Now it is time for grub.

Miyata Miyapet Intro

Yes, I added another bike to the stable. In this case, a make and model I had never heard of, which was part of the attraction to it. It is a Miyata Miyapet, made by the Miyata Bicycle company sometime in 1962 or 63. It is a bit of a mystery, as they apparently only made motorcycles for a couple years. So far I've only been able to find a few sales brochures for sale on ebay. Not much else with regard to history or technical specs. The brochures say it is 50cc, has a 3-speed with conventional clutch, is 12v, and has a starter.

C'

Possibly Buying a Miata

In this case, it is spelled Miyata. A Miyata Miyapet to be specific. I know hardly anything about this machine, and google isn't being very helpful either. Pics of this 50cc beast are below:

We'll see if I can arrange for pickup from the owner this week.

No Susan, I don't need another motorcycle. Thank you for understanding.