Yamaha FZ-16 or Fazer 153cc shares the same 153cc two valve engine. Its time tasted and proves to be highly reliable and smooth offering from this Japaneses manufacturer. One of the factor, due to the engines nature of being reliable is highly over looked by the users, that’s the tappet adjustment of valve clearance settings.
What is Tappet / Valve Clearance ?
The engine comes with two valve. One inlet and one exhaust. The inlet valve allow air and fuel mixture from carburetor to come into the engine combustion chamber and the after combustion, the exhaust valve allows the burnt gases to go out via the exhaust.
There is a specified gap, as you may see in the above illustration, which may needs to be adjusted over time, since the tension of the springs may increase of decrease.
What happens with wrong settings ?
Over time of usage, due to wear and tear, the valve sprint may lose tension or the rocker arm may lose its edge, hence allowing the gap to unsettle. If the value drops below specified limit, you may find starting trouble in cold weather, but usually the gap increases, and when it does, you would face host of issues.
- Vibration from engine.
- Noise from engine..
- Power loss in high RPM
- Effects in fuel economy as the bike starts to give low mileage
- With time, it would effect the valve and may cause valve damage and lead to engine seize !!
How often you may need to look into the issue ?
As per the Yamaha Service Manual, both user and service center, company recommends to check and adjust at every 12,000 kms, meaning once in every 4 service. But from our experience, we would say, you can safely do it at every 15,000 kms or once every year.
How do one adjust the valve / tappet clearance ?
Yamaha service center is the best place to get it done, but we advice you stand there with your bike and make sure they do it right. You may get it done from any experience mechanic also, but do supervise the process via this below guide on how to adjust the valve / tappet clearance of the engine.
Always make sure, the engine is dead code. Since metal expands in heat, so if one carries out the process of adjusting in warm or hot engine, the setup values wont be correct, so make sure there is at-least a 2 hour rest given to the engine to cool down before the work is done in the valve clearance adjustment.
Valve / Tappet Clearance values
Following are the values to set the gap,
Inlet -> 0.08 mm to 0.12 mm
Exhaust -> 0.12 mm to 0.16 mm
Open up the engine top cover
The top cover is right on top of the engine and can be removed easily by removing few screws to access the valve / tappet adjustment area.
Set the piston to TDC mark via the adjuster provided in starter clutch side.
Now one may use the filler gauge to slide into the gap and set into right value.
Once done, simply put the cover back on, and there you go, its done.
Its simple straight forward job, costs Rs. 100/- in service center and even less when done from outside, but helps to keep the bike in good condition so always make sure to adjust the tappet, once a year or once every 15,000 kms.