have i just been an idiot

[miker]

took stihl hs 85 hedge cutters apart today, after i had took the pot off i suddenly realised i hadnt marked where tdc was in relation to flywheel, does this affect the timing??? as now they wont start.........doh

[TimberCutterDartmoor]

no. it's 1 crank rev per 2 strokes so there's no timing to muck up!

 

Check for spark; coil pick-up needs to be pretty close to flywheel without touching!

[miker]

got spark, put a rizla flap under coil pick up maybe that is too big a gap

[miker]

and plug is wet

[Ian Leach]

Apart as in handle switch and all wires stripped too?? Could you have trapped the wires putting they plastic casing back on. earth

[miker]

took wires off the coil,and made a note how they went, i replaced the piston so thats how far i went in taking it apart

[spudulike]

Er - call me Mr Thicky from Thicksville but the flywheel should be keyed in to the crank, this dictates the ignition timing by keeping the magnets in the flywheel in the correct relationship to the coil position and crank position - at TDC, the magnets should be in front of the coil.

 

If you can rotate the flywheel in any position then the key has fallen out or you have crushed it if it is a moulded one in to the flywheel itself!

 

I have yet to come accross a two stroke that doesn't pick up the ignition timing in this way!

[spudulike]

no. it's 1 crank rev per 2 strokes so there's no timing to muck up!

 

Check for spark; coil pick-up needs to be pretty close to flywheel without touching!

 

Sorry - two strokes have to spark a few degrees before TDC same as fourstrokes, they spark on every revolution where fourstrokes need a spark every other revolution although many have a "wasted spark".

 

Flywheels on two strokes are always keyed on to the crankshaft so the magnets pass the coil at theright time to make the spark happen at the right time.

 

No offence meant but just correcting a mistake

[TimberCutterDartmoor]

Sorry - two strokes have to spark a few degrees before TDC same as fourstrokes, they spark on every revolution where fourstrokes need a spark every other revolution although many have a "wasted spark".

 

Flywheels on two strokes are always keyed on to the crankshaft so the magnets pass the coil at theright time to make the spark happen at the right time.

 

No offence meant but just correcting a mistake

 

What mistake?!

[spudulike]

Not sure if you are being serious but I was stating that both two and fourstroke engines do have systems in place to ensure a spark happens at the right place after you said two strokes dont have any form of ingition timiing - I could expand this on to cams and points as per much older two stroke engines but think thaat it best you guys send your blown up saws to me and I will fix them - broken flywheel keys a speciallity - I love backfiring chainsaws!!