Craftsman No Start

[lefty]

I will do that. What are your thoughts on valve adjustment in relation to this problem? I read some stuff on the interwebs speaking to that.

[lefty]

The spark plug was very black...sooty, if that information is of any help in this.

[lefty]

I just checked the valves. They're within spec, which is .004 - .008 for both intake and exhaust.

[bgsengine]

Its a lawnmower right? direct drive blade .. always check flywheel key betcha you find one partly sheared

[Fulltilt]

In addition, did you bother to check for a blown head gasket? Cyl leakdown test... or the ol' air in the plug hole while you listen trick???. Should have done it when you had the valve cover off, no?

[lefty]

Thanks BG. I'll tackle that soon.

Thank you also Fulltilt. Yes, I did have a successful leak down test on this one. About 4% loss at 92 lbs. Only sound was a little hiss from the dip stick.

How about this for a thought problem. After I changed the coil out for a known good one, based on KE4's theory, I had a complete no start. So I tested the coil on there for spark but didn't have one.

So I took the shroud off to examine the kill switch and noticed that when the kill lever is depressed, there isn't much travel in the wire. It seams the wire is too long and takes some turns that look sharper than I would have designed. And the two little pieces of metal do not separate that much when the lever is depressed.

I couldn't get my .006 gauge between the pieces of metal. After I manually squeezed the metal at the kill switch to make some more room. I think it may need some lube because when I let go, the spring brought it back but this time there was some more gap. Have a strong spark now.

The kill "tang" for lack of a better word, which is fixed and connected to the wire leading to the coil, appears bendable. May I bend that up a bit to make some room.

Is it a viable theory to think that maybe when things heat up, that switch may act up causing insufficient room between the two contacts? Has any one ever seen this? I'm thinking I bend that a bit, oil the pivot point for the kill lever, put her back together and give her a try.

[KE4AVB]

I have seen few where the kill wire actually make contact the engine metal ground as it just push through and capture by the spring effect of contact assembly. So I would also where kill goes into the contact.

[lefty]

I have seen few where the kill wire actually make contact the engine metal ground as it just push through and capture by the spring effect of contact assembly. So I would also where kill goes into the contact.

That picture is right on the money. The view is upside down as it is installed. So should I fiddle with it a bit?

[KE4AVB]

If you want to. It just a spring contact that the throttle lever must touch to kill the engine.

[bgsengine]

from the sound of things fiddling with that would just make things worse and no it is unlikely the clearance changes as it heats - not very much - Your issue as far as that goes is your MZR cable - it's either the wrong one (not uncommon) or it is stretched (housing shrank or melted or damaged) or the end where it pops into the handle is worn (very common) so that it tilts up towards the bail handle - and that little bit of tilt is more than enough to cause your clearance issue.

I think you have a sheared flywheel key judging by the sooty black spark plug (assuming your air filter is fine)

Just pop the flywheel nut off and have a look at the keyways to see if they line up or not and see about fixing or replacing your MZR cable with the correct one.. Flywheel Key $3 , Cable $18 - $21 in parts and thing's fixed most likely.

(Can you tell I have seen this exact situation dozens of times..?)