what have i missed?

[Jerry In Maine]

just finished exhuming an SJP.

when i first got it the piston was froze in the cylinder and in general it was a mess.
did a complete teardown/rebuild. new rings, gaskets, etc.

grabbing the spark plug wire and rotating the flywheel makes me say "Woo-Hoo" in a fairly loud voice so i know i have some degree of spark.

...and she won't run. most i've got so far is a couple pops and a puff of smoke from the exhaust. just for grims i exchanged the carb with a known good one off another motor. still nuthin'

can't figure what i missed. i never had to pull the points out before, but this one had some corrosion in the points box so i overhauled that too. set the point gap at 0.020". if i have spark could i have anything wrong in the ignition that could still keep the motor from running?

i think this is one of those "can't see the forest for the trees" type of problems...likely the issue is looking right at me - but for the moment i'm baffled.

[Charles uk]

All you need for it to run is compression, fuel & a good spark at the right time.

Now go away and check them all individually & post the results.

[Horsley-Anarak]

Spin it up with the plug out and grounded, do you get a nice spark?

If not my money is on a duff Villiers coil.


H-A

[charlesp]

Is the magneto baseplate in the right position, with its locating screw nose in the crankcase dimple?

[Jerry In Maine]

pulled the plug, wired a ground to the threads and got a nice fat, blue and steady spark, so ignition should be ok. ignition plate is properly mounted (but i can see a little fuel/oil around the joint where the plate slides onto the crankcase) and that loooooooong screw that holds the plate in place is secure so the timing should be ok

using known good carb - but did try two others i had on the shelf. piston is drawing in fuel since i can see fuel/oil drips from the exhaust. thought of a fouled plug especially since i did use a considerable amount of oil during re-assembly, but plug remains dry.

don't have a pressure guage to test compression - but it has as much as any of my others as best i can tell.

fuel is fresh as i mixed it this morning.

baffled. almost seems like a witch put a curse it. arm is tired from pulling the rope so i'll launch another seagull-jihad tomorrow morning.

thanks for the help!

[Horsley-Anarak]

Did you put the piston back the correct way up, lumpy bit at the top?

H-A

[Jerry In Maine]

yes h-a,
piston is lumpy-bit up!

thank you though, 'cause that the sorta thing i'm good at messing up!

[billyboy]

you do realise that the small engines are supposed to have more than double the compression of the big ones?

[charlesp]

The fact that the spark is ok doesn't mean the baseplate is right. Check that the end of the retaining screw is engaged in the dimple. It's that position that affects the timing, and if the motor has been stripped down that'll have been disturbed.

[Jerry In Maine]

...its in the dimple

[Charles uk]

Did you set the points with the flywheel in place?

[Jerry In Maine]

yes - set points with the flywheel in place

[Charles uk]

What position on the clock face is the magneto base plate locking screw when the spark plug is 12?
& have you renewed the spark plug cable?

This has got to be a real silly one!

[Jerry In Maine]

with spark plug at 12:00, ignition plate locking screw is at 6:00 and it was 2:30 PM EST when i checked.
plan to install an ignition plate off another working motor. have reason to belive that spark is intermittent.

[Horsley-Anarak]

My money is on a duff Villiers coil.


H-A

My money is still on that