Just follow the steps below. You can click the images to enlarge them.
Here are the steps taken to check the timing duration on a Homelite. You can use the same method on most small 2 stroke engines.
You will need a degree wheel, a pointer and a flash light.
For these steps you will need to remove the spark plug, the backplate, the exhaust header or muffler, the carb and intake manifold.
Mount the degree wheel to the crank. Then mount a pointer to the block. Now you are ready to blueprint your engine.
First lets do the intake timing. Rotate the crank while looking in the intake port."In the direction of the BLUE ARROW" You want to bring the bottom of the piston even with the bottom of the intake port. "SEE THE RED ARROW" (The port will be closed at this point) With your fingers through the backplate opening hold the crank in this location and set the timing wheel to zero at the pointer.
Now rotate the crank. (don't turn it using the timing wheel you might move the wheel and not the crank) Rotate the crank and look in the intake port as the piston goes up the port will open and as it comes back down the port will close. Stop it just as the piston covers the intake port."SEE THE RED ARROW" Now read the # off the timing wheel at the pointer. That will be the intake timing duration. (The amount of time the port was open in degrees) Remember the Blue arrow here shows the direction of the piston travel.
Now lets do the exhaust... This time looking in the exhaust port. Turn the crank until the top of the piston lines up with the top of the exhaust port. "SEE THE RED ARROW" ( Holding the crank in this location, turn the timing wheel to zero at the pointer.
Now rotate the crank "the direction of the piston is shown in BLUE again" (Remember do not turn the crank using the timing wheel).
Watch as the port opens and as the piston closes off the port."SEE THE RED ARROW" Look at the pointer and read the exhaust port timing. (The amount of time in degrees the exhaust port was open.)
By now you know to set the timing wheel to zero at the pointer before you check the timing duration. You also know to turn the crank and not the timing wheel. If you turn the timing wheel it could slip on the crank and your reading would be wrong.
OK lets move on to the transfer or blow down timing.
Here is where you will need the flashlight.(A small lamp will work as well.)
Take the light and shine it in the sparkplug hole.
Look in the exhaust port and rotate the crank until the top of the piston lines up with the transfer port line. "SEE THE BLUE ARROW" Then set the timing wheel to zero at the pointer.
Now rotate the crank "The direction of the piston is shown in RED" until the exhaust port closes "SEE THE BLUE ARROW" Then read the # off the timing wheel at the pointer.
(The amount of time the exhaust port was open in degrees from the time the transfer ports were closed until the exhaust port was closed.)
The last thing to make a note of is head clearance. Check it by using a small piece of solder. Put it in the sparkplug hole and make sure you have it over the wrist pin. If you don't the piston will rock and your will not have a good reading.
You rotate the crank. (smashing the solder) Then check the thickness of the solder. That will give you the head clearance.
Now that you know how to blueprint your Homelite engine you can move on to the next step.
Click Here if you have the New style 30cc Homelite Cylinder.
Click Here if you have the Old style 30cc Homelite Cylinder.
My goal is to help people get the most out of their Homelite engine.
I have gotten many emails asking about a timing wheel and pointer.
You can make both or I have them for $15.00.