Home Restoration Restoration topics Yamaha MF1 restoration, part 1#
Yamaha MF1 restoration, part 1#

The restoration of the Yamaha MF1 will take a long, long time! It is so old and rare that I have to be very careful while taking it apart.

 

I decided to start very slowly with the electrics. Normally I keep that to the last, but now I want to repair all parts when they are taken off the bike and put them immediately (as far as possible) in boxes, ready for later fitting.

Ready for "attack" with my tools! (26-01-2009)

 

Yamaha MF1 1961
Yamaha MF1 1961

The handlebar is a simple pipe with a welded-on pressing, covering the wires.

 

Yamaha MF1 1961
Yamaha MF1 1961

The flashers are riveted to the pressing, so have to be drilled-out.

 

Yamaha MF1 1961
Yamaha MF1 1961

The headlamp does not look very different from later ones. Already on this early machine the nice plastic connectors were used. Everythnig is in good order, just dirty.

 

Yamaha MF1 1961
Yamaha MF1 1961

 


Interior of the headlamp nacelle shows how much workmanship Yamaha already put into this little machine, at a time when most (if not all) European bikes only had electrical problems.

 

Yamaha MF1 1961
Yamaha MF1 1961

The Yazaki speedometer is stamped "351113". As it is a Japanese year, it means 35 + 25 = 1960, Nov. 13th. Therefore it is evident that the bike is produced in 1961.

 

Yamaha MF1 1961
Yamaha MF1 1961

The battery compartment under the seat is a bit rusty, but all components came out alrigth.

 

Yamaha MF1 1961
Yamaha MF1 1961

The handlebar lever assemblies were a bit worn. The l.h. side has a broken horn button.

 

Yamaha MF1 1961
Yamaha MF1 1961

 


And on the r.h. the switch knob misses. The wiring is also a mess. So that is the first small job to do!

 

Yamaha MF1 1961
Yamaha MF1 1961

(02-02-2009)

I checked all the old Yamaha Parts Books and legshields were used for many single cylinder models in the 1960's. The plastic shields were always "137" numbers (YA5). To my great surprise, such a set was still available for the YB100. I received it within 2 weeks and if I do not find original ones these can be made fitting (I only have to alter the 2 stays)

 

Yamaha MF1 1961
Yamaha MF1 1961

Turning back to the handlebar levers I have the brake lever so the clutch lever has to be made from another one. I found a lever similar in size and it was welded-up in the Yamaha workshop.

 

Yamaha MF1 1961
Yamaha MF1 1961

After that it requires a lot of very precise grinding and filing to get somewhere close to the original. Took me 2 days !!!

 

Yamaha MF1 1961
Yamaha MF1 1961

 


With a first bit of polishing with steel wool the assemblies look reasonable. As it is very risky to try to straighten the lever (l.h.) I just leave it as it is, nobody will see it. Polishing will be done outside when the weather is better, now it freezes in the Netherlands.

 

Yamaha MF1 1961
Yamaha MF1 1961

Next I have to renew all the electrical wires on the handlebar. Plastic hoses have cracked, etc. So from some old wiring harness I have taken the appropirate colors and soldered-up new sets. Here the l.h. wires need a shrink-tube on the horn wire. This is easily done with a heat-gun.

 

Yamaha MF1 1961
Yamaha MF1 1961

Completed this l.h. wiring can be fitted into the handle assembly when it is polished.

 

Yamaha MF1 1961
Yamaha MF1 1961

On the r.h. side I had to do the same. Here 2 small wires (green + brown) have to be soldered to the main green + brown flasher wires as direct connectors to the flashers. These 2, together with the electric start wire (blue/white) get an extra shrink tube. When sliding the wire package through the plastic tubing it is necessary to spray the wires with silicon-spray, otherwise it will be very, very difficult.

 

Yamaha MF1 1961
Yamaha MF1 1961

 


Next on the list is the dynamo

 

Yamaha MF1 1961
Yamaha MF1 1961

(11-02-2009)

With a small power tool and a felt polishing tip, using aluminium polish, the dynamo is brightly polished back to ( nearly) its nice finish from about 50 years ago.

 

Yamaha MF1 1961
Yamaha MF1 1961

The result is worth one hour's work.

 

Yamaha MF1 1961
Yamaha MF1 1961

Next are the front flashers. The rubber bases under the lenses are severely cracked. The easiest is to glue them with 10 second glue on a sheet of thin rubber. I always use old bicycle tyre inner tubes for these kind of small operations.

 

Yamaha MF1 1961
Yamaha MF1 1961

 


Now I have a temporarily repaired rubber bases. I have to repair the cracks later. maybe I do that with fluid rubber.

 

Yamaha MF1 1961
Yamaha MF1 1961

The horn came out virtually brand new. It only had to be polished. But it was hidden from the elements within the headlamp nacelle.

 

Yamaha MF1 1961
Yamaha MF1 1961

The voltage regulator cap was quite rusty. It was bead-blasted and re-sprayed. The base was cleaned and polished as the dynamo and the result is okay.

 

Yamaha MF1 1961
Yamaha MF1 1961

The speedometer is in a very sorry condition. I managed to take the rim off (it was dented all over) and straightened it. Cleaning comes later.

 

Yamaha MF1 1961
Yamaha MF1 1961

 


Apparently this little moped did not run much, as the ignition switch is quite okay. With 2 new chrome screws it can again be installed later.

 

Yamaha MF1 1961
Yamaha MF1 1961

Yesterday I brought these 7 parts to my chrome plating firm. Gearchange lever, kickstarter, brakepedal, the headlamp rim (2 pieces), the headlamp reflector (has to be silver plated) and the small speedometer rim. Cost will be Euro 175,00. For some of you this might seem expensive, but in the Netherlands these companies do not pollute the environment anymore. I am prepared to pay a little more for that.

 

Yamaha MF1 1961
Yamaha MF1 1961

The mufflers are another problem. My MF1 is a late one with a larger muffler, bolted to an extension arm on the frame. It is very rusted. I have a new muffler from an early MF1, which can be used (I fitted it on this picture), but then you see the frame extension. And I do not want to cut it off of course. i have to decide later what to do.....

 

Yamaha MF1 1961
Yamaha MF1 1961

It is very important to keep the old bolts, nuts and washers, as Yamaha used different dimensions in those early years. Most of the bolts had larger heads, what is 12/13 mm now, was 14 mm back in the early 1960's.

 

Yamaha MF1 1961
Yamaha MF1 1961

 


Same goes for the nuts of course, you can see that they are all larger (and thicker).

 

Yamaha MF1 1961
Yamaha MF1 1961

The washers are sometimes the same, but there arfe also many different sizes.

 

Yamaha MF1 1961
Yamaha MF1 1961

Wheelshafts, etc can be simply galvanised as well, on the MF1 they were not chrome plated.

 

Yamaha MF1 1961
Yamaha MF1 1961

Next we turn back to the engine. The rotor has to be removed and that can be a very diffficult operation. It took me 2 weeks to find a solution. Normally you use the Yamaha special tool, a bolt with a hardened pin at the end. But this did not work at all, the rotor did not come off. Next I used different sizes of shockpullers and it still did not work! On the picture I made puller under tension, trying to "screw" the rotor upwards. Again impossible!

 

Yamaha MF1 1961
Yamaha MF1 1961

 


Finally I turned to my friend Jan Smit http://www.jspp.nl/

and he did the trick within 5 minutes using some Dutch ingenuity and some Star Wars "The Force"! The solution is the following: use an old motorcycle valve, grind the head off and insert it into the hole in the crankshaft. The valve must be just so long that it ends under the (here 8mm) thread in the rotor. Screw a hard steel bolt into the rotor and use an airpower tool on the screw. It is simply "bang" and the rotor is loose. And nothing is damaged.

 

Yamaha MF1 1961
Yamaha MF1 1961

Now the r.h. crankcase cover can be easily removed. The clutch is the same inverse type as was later fitted to the YDS3 bikes and so.

 

Yamaha MF1 1961
Yamaha MF1 1961

All parts can now be taken off and laid down for a picture which I can later use for assembly.

 

Yamaha MF1 1961
Yamaha MF1 1961

 

Yamaha MF1 1961
Yamaha MF1 1961

 


The crankcases can now be split. After undoing all the screws I fastened the Yamaha special tool (expected the worse of course), but after a few turns of the rod the crankcases separated without problems. A small tap with a plastic hammer at the rear (as there is a fitting bushing there), helped as well.

 

Yamaha MF1 1961
Yamaha MF1 1961

Tap also the gearbox shafts a little while doing this.

 

Yamaha MF1 1961
Yamaha MF1 1961

The gear shifting mechanism is bolted into the left hand crankcase half and can be taken out as well, just 5 6 mm bolts.

 

Yamaha MF1 1961
Yamaha MF1 1961

The clutch can be pressed in by using a few sockets or so, then the spring can be taken out and the other parts. The single friction plate looks quite good fortunately.

 

Yamaha MF1 1961
Yamaha MF1 1961

 


(16-03-2009)

The crankshaft is in a very good condition. There are no marks on the shafts at all. The only small problem is that the small-end bearing bush is a loose fit. I have to make a new one. Unfortunately there is no room for a proper needle bearing!

 

Yamaha MF1 1961
Yamaha MF1 1961

The gearbox shafts and gears are also okay. Yamaha used very good material in those days and it is of course a simple 50 cc machine.

 

Yamaha MF1 1961
Yamaha MF1 1961

The crankcase halves are also without faults. At first sight I thought that there were small cracks everywhere but these were casting flaws.

 

Yamaha MF1 1961
Yamaha MF1 1961

(30-03-2009)

And the last picture of the final disassembly shows the larger painted parts, just before they went for cleaning.......!

 

Yamaha MF1 1961
Yamaha MF1 1961

 

 

 

 

 

 

 

 
 

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