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I understand I need top dead center(tdc) when adjusting the intake valves. Do I need to adjust to tdc when doing the exhaust valves as well or leave it for the intake and adjust from there?
 

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Hello Zuma125gal,

Once you move the piston to top dead center on the compression stroke, you can adjust both the intake and exhaust valves. There are different clearances for the exhaust valves versus the intake valves.

There’s a Yamaha Zuma service manual available for a free download here:

Scooter Service And Repair Manuals

There’s also some Youtube videos that illustrate how a valve adjustment is done. One of them is125ZumaGuy’s video is nice.


Best of luck. 🛵💨💨💨

— Rick
 

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Most OHC use the TDC-C [top dead center - compression stroke] method:
A. Watch intake valve go down, then when it starts to come up, look for the F-T kind of marks for Fire and TDC. Set both intake and exhaust at the same TDC-C. Find the T mark and line it up with the stationary mark. Don't need to move the crank cover off, use a wooden chopstick and follow the piston up at the spark plug hole, making sure the intake valve starts to close, so as not to tag the valve, and guide the stick up so it is not cocked at an angle coming out of the hole, if applies.

The second method is to remember the letters EOIC and a phrase:
B. This will be remembered by adding the words after you watch the event is to remember; 'as soon as', you see the movement's action is to 'stop.' Where it does not matter where you to start first, you look at the action of the valve's movement of either opening or closing and who is it in its stroke.
EO: You will watch the valves event and 'as soon as the Exhaust Opens, you stop.' Adjust the intake.
IC: Watching for the action of, 'as soon as the Intake Closes, you stop.' Adjust the exhaust.
 
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