Project Bike: Yamaha Jupiter-Z 2004, DIY Valve Clearance Setting Maintenance

Hi there! Long time no see. I’m moving now, living in my new old home and thankfully I had a job as engineer at an automotive components manufacturing. Well… I bring my 2004 Yamaha Jupiter-Z as my daily commuter and I had a several project. But first, I want to share you how I maintain this bike

As a period product the maintenance is crucial, tune up oil changing or event just checking the tire pressure and screw tighten. And honestly I almost never took my bike to the service center hehe, I conduct maintenance at various period; tire pressure checking at 500km at once, oil and battery checking at 1000km, oil changing at 2000km and so on. And the most important thing is the tune up, I conduct the tune up at 10000km at once. Why it take so long time? It because considering it was a daily commuter not a motorsport racing bike or a logistic vehicle that bring the engine to the maximum load, I pretty confidence with this formula.

So now the tune up except the oil changing I’m just doing a simple to do items;

1.   Clean and re-set the carburetor

2.   Re-set the valve clearance

3.   Checking the spark plugs

4.  And check the chain loose clearance

From those items we will discuss about the setting the valve since it is actually simple and quick to do 

So first thing first is take the front body off so the engine can be easily accessed

Move to left side crankcase then open the rotor and marking cover (see the picture above) with the flat-head screwdriver.

Then open the intake and exhaust valve cover at the cylinder head.

Of course took out the spark plug to enlighten the crank shaft manual rotation when set the top position.

After that rotate the crank shaft to positioned the piston and it’ valves to top position, keep rotating until the “I” mark at the rotor inside the crankcase can be seen. Once it seen check the intake and exhaust rocker arm shake it as the picture below shown. Both of the intake and exhaust rocker arm should can be move to those direction, if so the top position is complete, if not, keep rotating the crank shaft, wait another mark shown and re-check the rocker arm. 

Once it done you’re ready to set the valve clearance. It’s okay to start from intake or exhaust, but first you need to loosen the lock nut by rotating it counter clock wise then adjust the clearance by rotating the adjusting screw with special tools. 

The intake clearance I set at 0.08mm and the exhaust is 0.1mm, the exhaust clearance is bigger than the intake because the exhaust produce more heat than the intake, so the steel deformation because of heat is also bigger than the intake, that’s why the exhaust clearance is bigger than the intake. Those number of clearance is my private setting. I use it on the standard cub and matic motorcycle 100cc until 125cc. I determine that number only base on experience, the 2004 Yamaha Jupiter-Z official clearance is 0.1mm for the intake and 0.12mm for the exhaust. I decrease it into 0.08 and 0.1mm because I need more efficient of valve stroke and minimize the noise from the rocker arm, it is safe from the leakage even I applied it to my racing camshaft that have higher valve lift than the original. Hope we can discuss to prove my private setting with the proper literature and calculation on the next time hehehe

Oh I forgot to explain how to fix the clearance; like shown on the picture above tighten the rocker arm’s adjusting screw and lock the lock nut with the feeler gauge still in the middle of rocker arm and valve to mold the clearance amount. After it locked up check the clearance again with slide the feeler in, if it can be slide at the medium force and had a little friction resistance the adjustment is ok, but… if it slide easily with no resistance or it difficult to slide even can be slide, the clearance need to be adjust again. 

Then you need to assemble the components again with the backward step of the disassemble step:

1.      Lock the rocker arm

2.      Assy the crank case cover

3.      Put the spark plug back

4.   Put the rocker arms cover back

OK, I wish that you guys could set your own 2004 Yamaha Jupiter-Z now but if your bike is not Jupiter-Z  don’t worry because this is the basic step to adjust the valve clearance, it can be adopted to another models. Well, see you at the next discussion also I’m in working of changing my project bike’s rims and tires so wait for it, see ya 

Regards,

Gigih P.