setting timing on a 2 stroke engine

[flatyre]

just fitted a new pot and piston to my Makita DPC6400 and can't get it to start, not even a splutter. it has good spark and a refurbed card, but even when I put petrol straight into the bore it still won't even fire. Can you mess up the timing on a 2 stroke, and how do you re-set it?

[adw]

The ignition timing would be set by the flwheel key, if the key has sheared then yes the timing will be out, you also have port timing so was it the correct cylinder and piston for the saw?

[harrythecat178]

Check flywheel key isnt broken, thats the only way to move timing

[spudulike]

You have ignition timing set by the flywheel magnet position, the flywheel key, the crankshaft and the coil.

 

You also have port timing which is set by the position and height of the cylinder and the dimensions of the piston.

 

If the correct parts are used, the ignition timing can be knocked out by a broken flywheel key or a coil failing. The timing of the cylinder can't be changed without grinding out metal or changing base gasket height.

 

It is more probably that the carb has been rebuilt incorrectly or there is another fundamental error with the rebuild.

[peatff]

Which way round did you fit the piston ?

[flatyre]

arrow pointing to the exhaust port.

[peatff]

If it's got a good spark and it's not kicking with fuel straight down the plug hole There's something fundamentally wrong, did you fit the piston rings ? (only kidding) If it was running before and you've done nothing to the flywheel then there should be no alteration to the timing. Even without the key the nut will hold it in place if it is tight.

[flatyre]

I bought it as a non runner, got the carb sonic cleaned but wouldn't run, piston wasn't the worst but fitted the new one and barrel, still won't run:confused1:

[Neil-R]

Has it got the correct coil fitted?? , many Makita /Dolmar models have different versions of ignition coils for one model of saw , if the wrong one is fitted the timing can be radically different , been there myself with a DCS500 fitted a black coil rather than red , would not even try to start

 

 

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[Jiles]

Have you checked compression? Hard to get anything to even pop, with less then 125#