Petter M 1.5

Hi Chaps,

I spent an interesting but not very fruitful morning trying to kick some life into my newly acquired 1.5 Hp Petter M:

Crank, crank - - - No Spark :(

Clean magneto points,

Crank, crank - - - No spark :(

Strip magneto - - - secondary open circuit :(

Swap magneto for known good item.

Spark! :)

Crank, crank - - - No Fuel :(

Strip mixer

Q. The books I have indicate that the bigger 'M''s have a cone type fuel collector, mine doesn't. Is this normal for the 1.5 HP? The atomiser on mine is just a block with a few holes in it.

Clean / rebuild mixer.

Crank, crank - - - Nothing :(

Crank, crank - - - Compression seems a bit feeble. :( :( :(

Whip head off.

Bore looks OK, not oversize, no wear ridge, not much piston movement. New Rings required?

Crank, crank - - - fuel getting in now :)


Crank, crank - - - Nothing except a blister on thumb (the one that's kept out of the way when cranking - b*****ks) :(

Swift application of easy start - - - Nothing but smoke from exhaust :(

Check air valve clearances (desperation setting in) - - - OK but reset to


Crank, crank - - - b****r all!!!! :(

Chucked a couple of squirts of oil down the plughole to gain some compression (and some more easy-start).

Crank, crank - - - more smoke from exhaust, otherwise b****r all :(

Fed up - - - Get coffee and go and do something else! :)

So .................

Is there something missing from my atomiser assembly?


To ask the question for the thousandth time, who is the best bet to supply piston rings?


Any other ideas?

Best regards but a slightly dejected,


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Only the early ones have the cone type, approx pre-1919. A plain atomiser is correct for yours. There are three possibilities in order of likelihood: The atomiser is too far from the piston (reset to 1/16") it may have been broken off. half mine have been. The atomiser is blocked. Clear with brass wire - holes go right through the diagonals You have ball trouble. The ball in the elbow twixt carb and atomiser is not sealing hth Roland (who bought a nice Victory 5hp today :-)

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Roland Craven

Reply to
Roland Craven

Would the "victory" be yet another Petter

Mart> On further thoughts....Assumecarb is getting fuel??

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Might be :-)

Reply to
Roland Craven

Thanks Roland,

Fuel is getting through (now), I could see it being pulled into the bore when I took the head off and turned the engine over. I reset the atomiser to

1/16" from the piston so I guess the lack of compression and therefore the rings are the problem. I'll strip the thing down soon for a proper inspection.



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The normal CR is only 4.5;1 and they'll start with 3/10 of the cube root of BA. Also unless the rings/bore are totally shot the compression will rise with a run especially on load. I'd try a different plug first.... Just back with my tan from Yesterday's Farming which just seems to get better every year. John Manders happy as Gas-turbine APU absent :-) hth Roland

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Roland Craven

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