My Yamaha YBX Restoration

[kiranby]

Hi all,
I am back with my YBX 125 restoration story. Let me first describe my ybx and my experiences associated with it in a step by step manner.

Year of manufacture : 1999 (non AIS)
Color : Black
Location : Bangalore
Mileage : Best 55 kmpl (city conditions)
Worst : 32 kmpl !(city)
Top speed achieved : around 118 kmph (on highway of course !)

Performance :
Believe my guys, at this point there is no second word. It performs very neat, its throaty and roary unlike other silent four strokes. The throttle response is simply superb. One has to ride it to believe it. Its response is very near to powered 2 strokes. It takes no time to reach high speeds. It always reminds me of the legend RX 100. There are many similarities between YBX and RX100. It can easily catchup with bigger bikes, atleast to some extent. Once i had a bigger rear sprocket (2T extra), the performance figures were superb. 0 to 60 in 6 seconds and 0 to 100 in just 11 seconds ! With the stock set-up the drag speeds in each gear experienced by me are as follows -

1st gear - upto 40 kmph
2nd gear - upto 60 kmph with a mad rush !
3rd gear - upto 80 kmph with mid range torque at its peak
4th gear - 100+ vrooooom !

My ownership experiences with it are simply awesome ! It never let me down in any circumstance. Before the restoration, i had covered around 1.6 lac kms on the ODO ! It was still doing hard. But pickup and mileage were bit poor with lot of engine noise ! So i decided to give a new lease of life to my baby !
Here are pics for viewing pleasure

 

[roman]

The ybx was a decent performer back in the 90s when yamaha had to shut down it's 2 strokes and i have driven this bike extensively, but I think your speedo was way optimistic ,don't think the ybx is capable of hitting those speeds. From what I remember it was a mileage oriented bike in replay to the rising oil prices.The speed you mentioned could be achieved only by shoguns and 135 back in the 90s

Can't believe that a bike can hit 40 Kph in the first gear(it will roast the engine for sure)
Please specify the restoration works in detail

 

[Mr.Boss]

Nice to see another 2 wheeler restoration job. All the very best.
Do post detailed snaps.

1st gear - upto 40 kmph

Can't believe that a bike can hit 40 Kph in the first gear(it will roast the engine for sure)

That's exactly my point as well. This is possible at 2 instances,
1) Though I don't have the actual drive ratios of YBX, assuming a similar ratio from RX135 to reach 40kmph in 1st gear one should do 9500 rpm at crank.
2) Faulty speedo

 

[Releesh]

Boss, Roman@

it may be possible with that bike if he upgraded the rear sproket with a smaller sprocket in rear, it surely do. But he mentioned he added a bigger one and no information about front sprocket. I checked it couple of years before in a Suzuki Fiero(on stock set up) and it reached near to 40km/hr in first gear, but it is not possible to change to 2nd suddenly. Even though if we applied clutch and reduced accelerater, it'll take some seconds to RPM come down and then only gear will slot to 2nd.

Though i didnt checked the top speed on 1st gear in Ybx, but i had extensive experiance with Enticer,old fazer, Gladiater and crux. Enticer & fazer has same engine with 4 speed and Gladiater has 5 gear. I am sure these bikes easily reach 30 km/hr in 1st gear. In Enticer, i were changing to 4th gear only after 80-90km/hr.

I had once fixed Rx 135 (5 speed) chain & sprocket( 32/36 teeth in rear i guess) in my gladiater and then,
Bike was catching more speed very easily in each gear,
felt Torque reduced and 5 gear is almost unusable
engine become so silent than unicorn in running and milage incresed.
problems were, bike may not move from standstill with a pillon or not take much load.

Roman@

YBX was a good powerful bike and performance is almost equal to some 150 cc bikes. More than 50 kmpl milage on this 125 cc bike will be a rare case.

 

[kiranby]

Hey, thanks all for going thru my post.
@ roman, Mr. Boss, the speedo is right. I have touched 40 kmph in first gear several times. The bike had stock sprocket at the front. It was tuned by a master mech in bangalore. Believe me guys, the drag speeds mentioned by me are correct. I have even raced my ybx with my friends rx135, fiero and CBZ on highway. It could easily catch up with them. After restoration i have ridden around 3500 kms, but havent tested drag speeds. Will soon test and post.

@Releesh, yes its performance is equal to most of 150cc bikes available today. It gives me 50 if driven in a decent manner. Mileage goes down if ripped.
Will put more pics ASAP.

 

[roman]

Roman@
YBX was a good powerful bike and performance is almost equal to some 150 cc bikes. More than 50 kmpl milage on this 125 cc bike will be a rare case.

Yamaha ybx was marketed as a stable,economic bike in contrast to the hara-kiri rx 135 and rxz of those era. It was the first yamaha 4 stroke .I had ridden that bike it was a decent performer but not hair raising as the two stroks and in it's stock condition i would rate it along with the later gladiators,ybrs.

Good restoration this bike is certainly a reliable workhorse

 

[kiranby]

Hi all, lets look at the concluding part ! Even after 15 years, the bike looked new with minimal scratches. The paint and chrome were intact. So i decided not to touch them and rebuild only the engine.

In the month of october 2014, i decided to restore it to its past glory. So started hunting for oe parts. There i came to know how difficult is it to procure oe parts. Yamaha guys have completely stopped supply of parts for ybx, so i had to search for oe parts with automobile dealers across bangalore !

It was my routine practice to enquire at each and every automobile shop en route my work place. None of the spares were readily available, so i had to book them against advance payment and eagerly wait for them to arrive ! The process of acquiring spares itself took nearly a month. Later, my job was to find a good mech to do it. This was even more difficult task, as you all know how competant the mechs are these days !

Finally almost all the parts arrived ! I am making a list of spares acquired below, as this may be useful to other members.

1. Rear wheel hub (oe)
3. Rear tyre with tube (Birla, 3.25 18)
2. Engine gasket kit (aftermarket)
3. All oil seal kit (oe)
4. Axel drive (as the old one had uneven splines !)
5. Guide stopper
6. New cylinder piston kit (oe)
7. Chain sprocket kit (oe)
8. New clutch plates with steel plates
9. New battery (Exide)
10. Tail piece (as old one was missing !)
11. CDI unit (india nippon, oe)
12. Wiring harness (swiss, as oe was nowhere available)
13. All control cables (oe)

Engine works carried out

1. Crank resetting with new bearings (SKF)
2. Head decarbonizing with new valves

here are the pics

 

[RVSB]

IIRC, There was also another bike looking the same. Its name is YD-125 I think.
The YD was one reliable workhorse. I saw a guy pulled up a 12 o clock wheelie on that one.
It can handle all the abuse that one Indian can do!

 

[kiranby]

@RVSB, yes thats yd125. Actually YD was a simple looking version of YBX.

Friends, now comes the engine rebuild story.
As the engine assembly began, some parts were replaced viz, rocker cam, timing chain etc.

My mech took 4 full days to complete engine overhaul. Finally the moment arrived for which i was eagerly waiting for ! A petrol bottle was connected and bike was started. It started, but to my utter surprise, there was a knocking sound coming out of engine ! Mech told me to run the vehicle for a week and the sound will vanish. But even after running it for a month, the knocking sound continued. I was totally down.

I literally fought with him and went to some other mech in my area. The new guy found the root cause of it ! It was actually coming from the big gear wheel behind the clutch bell assy. It is called "driven gear ". Again search started for that part and it was nowhere available. He then machined a faulty tooth on it and fit it back. But luckily the sound had gone and it was all smooth and original !

I thought everything ended smoothly, but it was not. Bike was running smooth with lot of missfires ! Again i started to scratch my head as no mech was able to solve this problem. Later i went to an auto electrician, who carefully examined my magnet coil and adviced me to get it enhanced with extra no of turns. I agreed and work was executed. Voila !, after a nice ride and tune, its all original guys ! I said UFFF... and enjoying it again like before.

Here are the pics ......

 

[om_nivaz]

Nice to see your thread. Now the engine is rebuild. Why don't you try replacing all the body parts. I see there are some scratches in front headlight doom... It's worth giving a full shot resto to the baby...
Long live ybx.

 

[kiranby]

Nice to see your thread. Now the engine is rebuild. Why don't you try replacing all the body parts. I see there are some scratches in front headlight doom... It's worth giving a full shot resto to the baby...
Long live ybx.

Hey thanks for going thru my restoration post. I have replaced my headlight with autopal 50/60 round doom. Other body panels are intact. So i dont think i need to replace them in near future. Anyway thanks for your advice. I think its worth every penny spent on it. Lets keep YBX spirit alive

 

[Nesarkiran]

Hi all,
I am back with my YBX 125 restoration story. Let me first describe my ybx and my experiences associated with it in a step by step manner.

Year of manufacture : 1999 (non AIS)
Color : Black
Location : Bangalore
Mileage : Best 55 kmpl (city conditions)
Worst : 32 kmpl !(city)
Top speed achieved : around 118 kmph (on highway of course !)

Performance :
Believe my guys, at this point there is no second word. It performs very neat, its throaty and roary unlike other silent four strokes. The throttle response is simply superb. One has to ride it to believe it. Its response is very near to powered 2 strokes. It takes no time to reach high speeds. It always reminds me of the legend RX 100. There are many similarities between YBX and RX100. It can easily catchup with bigger bikes, atleast to some extent. Once i had a bigger rear sprocket (2T extra), the performance figures were superb. 0 to 60 in 6 seconds and 0 to 100 in just 11 seconds ! With the stock set-up the drag speeds in each gear experienced by me are as follows -

1st gear - upto 40 kmph
2nd gear - upto 60 kmph with a mad rush !
3rd gear - upto 80 kmph with mid range torque at its peak
4th gear - 100+ vrooooom !

My ownership experiences with it are simply awesome ! It never let me down in any circumstance. Before the restoration, i had covered around 1.6 lac kms on the ODO ! It was still doing hard. But pickup and mileage were bit poor with lot of engine noise ! So i decided to give a new lease of life to my baby !
Here are pics for viewing pleasure

I also wanted to do engine rebuild for my ybx can please guide me good mechanic in Bangalore it's urgent reply soon or else give me your contact no I'll call you

 

[Pradeepsg]

Hey thanks for going thru my restoration post. I have replaced my headlight with autopal 50/60 round doom. Other body panels are intact. So i dont think i need to replace them in near future. Anyway thanks for your advice. I think its worth every penny spent on it. Lets keep YBX spirit alive

Kiran, pradeep here. I'm working in getting my bike restored as well. Need some advice, can you ping me pls?