cg125 : removed flywheel, now timing is maybe mehhhh

[speedingmotor...]

hello bcf

i removed the flywheel on my 1979 cg125 because i had to replace my contact breaker points, i tried my best to keep the flywheel in line when i put it back on, but i kind of feel like the timing is now off. it wont rev as high in the rpms as before, and when under load, it seems sometimes on the verge of backfire. perhaps i did something wrong? is there a way of checking readjusting the timing? i dont have the lamp, but i could go see my mechanic i guess. more intersted in understanding/figuring it out.

:: edit :: should i set the piston at TDC and refit the flywheel??


thanks bcffamily


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https://www.youtube.com/watch?v=zojEIR_SGSk

[cb1rocket]

This one is tricky to explain. But basically you need to set the gap on contact breaker correctly and in the correct positon. The flywheel is fixed by means of a woodruff key on the crankshaft spindle so isn't adjustable. If you have a meahanic I'm sure he would show you how it done if you pay him hood money.. there is also a mark on the flywheel that should align with a mark on the crankcase.

Someone will explain better than me
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[speedingmotor...]

hey cb1 rocket, thanks, so the flywheel will always stay in the "correct place" the loss of power could be from the gaps not correctly set?
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https://www.youtube.com/watch?v=zojEIR_SGSk

[MCN]

You probably have to set the piston to a position just before TDC. TDC is too late for the spark.

The thing that makes the spark points or CDI will have a rotor which is 'fixed' via a 'taper fit' to the camshaft which is synchronised via gears to the crankshaft.

If you haven't fcuked with the rotor position then the timing is OK.

(To check timing you need to determine the angle of the crank by sticking a rod down the spark plug hole and measure the depth when the rod contacts the piston. This is the Degrees Before TDC.

Ignition is always timed before TDC because of inertia in the mass of the piston and crank passing over the centre line of the crankshaft.

Not all engines are set at the same angle.

You can google this yourself.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[mudcow007]

Is this any help?

https://hondacg125.awardspace.com/basic_fault_finding.htm#Ignition-Timing

[Stoker]

It's the valve clearances that are checked at TDC, (top dead centre), which is the "T" mark....... You need to set the points at the "F" mark.

You should be able to adjust/set the points without removing the flywheel. The flywheel is kept in its correct position on the shaft by a small piece of steel called a woodruff key, which locates in slots on the shaft and in the flywheel.....if this ain't missing or deformed, the only thing affecting the timing is your adjustment of when the points open.

[speedingmotor...]

thank you everyone, i will have a look and report back


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https://www.youtube.com/watch?v=zojEIR_SGSk

[bikenut]

lets hope the fibre heel is still intact, and/or, the points "arm" is still "unbent".

When fitting the points, adjust the points "base" via the locking screw, so that the points ( and the heel and arm ) are "furthest away" from the flywheel points "cam", that's the "bump" part on the inside of the flywheel, the bump opening the points.

Then fit the flywheel etc. and adjust the points gap via the adjusting screw and flywheel window.

Is the points arm "unbent" or bent due to poor flywheel refitting ?
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