Restoring Yamaha 100cc (YB100, model:1980)

[fakhir]

Hi everyone,

I have decided to restore my dad's old YB100. It has been lying around in the garage for 10 years or so. I would also like to mention that I have absolute ZERO experience regarding bikes or engines and not even remotely related to those, this is my first ever project.

PS: Since I am a bit busy with my own projects, the progress on this is going to be a bit slow (probably only weekends). And this project can even fail due my lack of experience !


OK enough talk, let's get started:

Original condition: The bike appears to be in a pretty bad shape:




Special thanks: I would like to thank our respected pakwheels member @vickytulla (Waqar) for the much needed initial guidance.

[fakhir]

Went to bilal ganj and bought some tools. The pressure gauge and impact screw driver are two very cool tools that I've ever owned:

Another angle of the bike:

Yet another angle:

Looks like it was a heaven for spiders:

[fakhir]

Cleaning the Bike

There was loads of gunk and dried out mud underneath the engine. Probably that resulted in huge amount of rust.

Lesson: Always clean off dirt and mud from your bike as frequently as you can.

I used soap and some scrubbing brushes. Majority of the gunk is gone. Only very tough patches still remain under the engine which I plan to remove later. Bike looking a lot better now:

[hidalgo]

MASHALLAH its gonna be a nice restoration . we also had same 1979 model yb100 its number was gaa 8084 my dad literly loved that bike but in 2002 we had to sale it due to financial crisis . but its my wish to find it buy it resto it n gift to my dad . there are many more experienced guys regarding bikes here but i am here to help you as my lil knowledge is considered regarding yb100

[hidalgo]

how much the grey tool kit costed you ? it costed me 2.3k from b gunj

[fakhir]

Damage inspection

Time to do a close damage inspection.

Battery acid appears to have damaged the side cover:

Battery acid is probably spilled every where. Huge amount of rust everywhere:

Chain cover is full of rust:

Odo meter is in a bad shape. Flasher covers are broken, bulbs probably fused:

Right side of the engine: Rusty, soft and deformed screws. It is going to be a total nightmare while opening these up:

Right side of the bike:

[hidalgo]

i can give u a price estimate for cosmetics and engine rebuild .

[fakhir]

Thanks a lot !

how much the grey tool kit costed you ? it costed me 2.3k from b gunj

The 52 piece socket spanner set? Well I got it for 2.1k on a discount LOL !

[fakhir]

i can give u a price estimate for cosmetics and engine rebuild .

Sure please ! Any kind of help is appreciated . But I don't think I may be able to get original parts. And I don't want to use new model parts on the bike. My primary goal is to get it running. Cosmetics etc are 2nd priority (but still important).

[hidalgo]

Sure please ! Any kind of help is appreciated . But I don't think I may be able to get original parts. And I don't want to use new model parts on the bike. My primary goal is to get it running. Cosmetics etc are 2nd priority (but still important).

better take it to any mechanic or flush engine oil , clean its carborator , replace spark plug , fuel it ( mk sure tank is clean)
if current is still there , chances are that you may start it even at home by your self

[hidalgo]

fakhir both fenders approx 600 pkr
seat 650 pkr
speedo 450pkr
indicator covers 5 rs each .

[hidalgo]

for complete engine rebuild including labour u ill stay under 5k budget limit and do it easily

[fakhir]

Some major damage in the rear fender:

Rear view, some more rusty parts, broken components:

Dents in the tank:

And loads of rust at the rear end of the fuel tank. There are probably some holes as well:

Gear shift pedal appears to be deformed:

Getting battery out of the bay:

Rectifier mounting plate has almost disintegrated. And God knows what other junk was lying around inside the battery chamber:

[fakhir]

better take it to any mechanic or flush engine oil , clean its carborator , replace spark plug , fuel it ( mk sure tank is clean)
if current is still there , chances are that you may start it even at home by your self

There is absolutely no current nor any spark. Maybe I need to analyse the generator assembly later down the road.

I won't take it to any mechanic. It is my bike and I will restore it myself at home (well as much as I can). So instead of giving 5k labour to the mechanic, i'd rather buy some cool tools for myself !

[hidalgo]

after market tanki tapay available for 1.2 k
all rates m telling u are in pindi they will be more less in lahore

[hidalgo]

There is absolutely no current nor any spark. Maybe I need to analyse the generator assembly later down the road.

I won't take it to any mechanic. It is my bike and I will restore it myself at home (well as much as I can). So instead of giving 5k labour to the mechanic, i'd rather buy some cool tools for myself !

going to mechanic is not bad , i was saying as its ur 1st project so u should keep it simple for ur self . rest as u want . ps how much is the pressure ? and how this pressure guage works

[fakhir]

Mouse droppings LOL. Looks like the mouse has been chewing wires and battery container, explaining acid leakage:

Electrical system is a total mess:

Spark plug seems to be in healthy condition. There are no oil, deposits or erosion on the electrodes, probably hinting that the engine was also in healthy condition (but let's see). By the way before taking out the plug or the battery I tried to start the bike (10-15 kicks) and there was absolutely no spark in the plug electrodes.

More broken parts:

[hidalgo]

how you checked current

[fakhir]

going to mechanic is not bad , i was saying as its ur 1st project so u should keep it simple for ur self . rest as u want . ps how much is the pressure ? and how this pressure guage works

Pressure gauge is pretty easy to operate. Just take spark plug out of the head and insert the pressure gauge into that hole. Now crank the engine 4-5 times until there is no more pressure rise on the gauge. On a bike, around 4-5 kicks will do. But I do know that if pressure is anything less than 100 psi, you need to rebuild the engine (or set valves etc). If a piston has 100 psi pressure then it means that it is on its death bed. CG 125 has 145 to 170 psi according to factory specifications.

I didn't measure the pressure yet.

how you checked current

For now I just took the plug out (making sure it is still connected to the generator assembly) and placed it close to the head and cranked the engine (4-5 kicks in this case). No spark at all. This means either spark plug is faulty or the ignition switch is not working or even whole generator assembly needs some serious attention. Since I planned to open up the engine anyways, i didn't bother going into electrical details. But maybe in near future!

[hidalgo]

good going . i suppose u not that new to bikes u can do it easily .