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Can anybody please help have no spark on my Sthil ts420 have replaced flywheel coil Cutout switch and spark plug but still no spark can anyone please help

see page 46 for specifications, check spark plug gap, check air gap from coil to flywheel, use 93 octane gas with Stihl two cycle oil.

mechanic mark said:

https://m.stihlusa.com/WebContent/CMSFileLibrary/instructionmanuals/STIHL-TS-410-420-Instruction-Manual.pdf

see page 46 for specifications, check spark plug gap, check air gap from coil to flywheel, use 93 octane gas with Stihl two cycle oil.

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Thanks for reply have checked all these things you have mentioned but still no spark

Unplug the kill wire and then try to start it... if it sparks the wire could be grounding before the switch.

Scrubcadet10 said:

Unplug the kill wire and then try to start it... if it sparks the wire could be grounding before the switch.

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Just tried it still no spark apart from the flywheel everything is new and gapped correctly have tried a second hand flywheel but still cannot get a spark at the plug is there anyway to check the flywheel? Looks ok doesn’t seem to be cracked or anything

You may not be spinning the flywheel fast enough, do not try it with a drill, but put the starter back on, and check for spark in a dark room. The newer ignitions do not put out too bright of a spark.

Have been trying with drill thought that’s was the best way ?

Drills do not spin the flywheel fast enough to test for spark.

get a screwdriver or magnet and see how hard the flywheel magnets are pulling.

Magnets seem strong going to refit starter and try it again cheers

Magneto coils are polarity sensitive .
Have you installed it right way round ?
Usually marked "engine side"

Question. Did the new come with the high tension lead or did you reuse the old one? If reusing the old lead it might be the problem.

Yes coil will only fit one way and it came with ht lead and cap fitted good news have got a spark but still not starting think someone’s been changing carb settings going to try and find the settings for carb and give it a try it’s nearly started but not quite

Take off the muffler and peek at the piston.
Or peek at the intake side if you have the carburetor off, you will likely see nothing good.

First check the cylinder condition as Fish suggests.

Following is assuming the limiter caps have been removed and is the initial carb settings.

: Turn the high speed screw H (1)
clockwise until it is firmly in its
seat.
: With the high speed screw H (1)
in its seat, give it 1.5 turns
counterclockwise to obtain the
basic setting.
: Turn the low speed screw L (2)
clockwise until it is firmly in its
seat.
: With the low speed screw L (2) in
its seat, give it 1 turn
counterclockwise to obtain the
basic setting

These carbs are sensitive to adjustment, a little bit goes a long way!

Thanks all will give it a go tomorrow let you know how I get on

Does anyone have a diagram of where the fuel lines fit as I have just discovered that the primer bulb had been bypassed because it was faulty have now fitted new primer now when I try to run the engine after priming it runs for a few seconds then stops know carb has three connections for fuel line the tank has a high and low connection
And one goes to the air filter as a breather but cannot workout which connects where