Re: Petter A1 Starting Issues

by Stu Pashley Sat Sep 26 2020, 09:37

StuartTurnerSteve wrote:The impulse coupling retards the spark until just after the piston passes top dead centre for starting, so should be opening as the impulse clicks.

15k ohms sounds high, 3-7KOhms is what I tend to look for. Pull the suppressor cap off.

Thanks have cut suppressor off and is now own to 5 K Ohm's so will make a new HT lead up.

by Stu Pashley Sat Sep 26 2020, 09:38

maryalice wrote:As told by my magneto repairer, Bin the suppressor they bugger magneto's.

Maryalice

Thanks have cut suppressor off and is now own to 5 K Ohm's so will make a new HT lead up.

by oldgit Sat Sep 26 2020, 11:04

Stu Pashley wrote:
Gaudin98 wrote:The mag is fitted 180 degrees out.
Would that not mean it would then be firing at BDC rather than TDC. If I turn it over it fires at TDC put points seem to close before impulse rather than opening

Did you check this out.
Gaudin98 is suggesting that the magneto rotor is 180 degrees out.
This would would make it 360 crank degrees out; causing the spark to occur at the, end of exhaust/start of induction stroke, rather than end of compression stroke.
if this is the case; your engine will not start, no matter how good your spark is.

by Woodsman Sat Sep 26 2020, 11:11

Re oldgit's post.
Why not just whip the head off and watch the valves cycle ?

by oldgit Sat Sep 26 2020, 11:25

That sounds good.
Or take the plug out and maybe you will be able to see the valves.
Or, press your thumb on the plughole and you will be able to identify the compression stroke by feel as you turn the crankshaft.

by Woodsman Sat Sep 26 2020, 15:03

Got there before me oldgit Smile

Note to self - THINK before posting. Embarassed

Should be able to feel the compression as you turn it over. Thumb over spark plug hole will indicate if there is some compression but not enough - should get a little burp just before impulse trips.

by Woodsman Sun Sep 27 2020, 10:36

Just had a duh moment. Embarassed

My A1 had a decompression lever fitted so you could crank like billy-o to get it spinning then let go of the lever to get compression.
Stuart please confirm either way.

by Appletop Sun Sep 27 2020, 17:11

[quote="Woodsman"]Just had a duh moment. Embarassed

My A1 had a decompression lever fitted so you could crank like billy-o to get it spinning then let go of the lever to get compression.
Stuart please confirm either way.[/quote]

Oh no you don't!!!! The Petter A1 has an impulse on the magneto and you should only need to pull it smartly over compression and not "swing it like billy-o". All the decompression lever is for it to allow you to turn the engine over for service use and is not a starting aid.

by oldgit Sun Sep 27 2020, 20:57

Did they make a diesel version of this engine?
I only ask as it seems an extravagance to have a de-compression system on a spark ignition engine.

by maryalice Sun Sep 27 2020, 21:28

My Lister L had a decompressor on it as standard as does my Lister M, without it they are pigs to get going let alone start, its not uncommon.

Maryalice

by Appletop Sun Sep 27 2020, 22:00

[quote="oldgit"]Did they make a diesel version of this engine?
I only ask as it seems an extravagance to have a de-compression system on a spark ignition engine.[/quote]

Yes, the PAZ1. Same base bolt holes but most of the rest is different.

by StuartTurnerSteve Sun Sep 27 2020, 22:06

Or the AA1.

Some Petter A1s had compressors, on the valve chest IIRC.

My little Condor has a decompressor, still the engine will stop you dead if you don't catch it right.

by Woodsman Mon Sep 28 2020, 10:32

Appletop wrote:
Oh no you don't!!!! The Petter A1 has an impulse on the magneto and you should only need to pull it smartly over compression and not "swing it like billy-o". All the decompression lever is for it to allow you to turn the engine over for service use and is not a starting aid.

Petter A1 Starting Issues - Page 2 Starti10

by Foden Mon Sep 28 2020, 10:44

Presumably during a 'brain failure' I remember picking an A1 up a few years ago for £20 and it had been 'rebuilt' by somebody in the past but they never got it running so they sold it at a farm sale and I got it from the lad who bought it just for the mag but then decided to sell it complete. The rebuilder had obviously tried hard as the plug threads were stripped where he had it out that many times, I recut them to 18mm. However to get back on track: the magneto was 180 degrees out, the throttle linkage was upside down so it was permanenty closed and on investigation it had new rings fitted but the con-rod was the wrong way round, other than that he had made quite a good job of it! Smile

It ran quite well eventually, but as I didn't rally it much I sold it on.

Pete.

by Stu Pashley Mon Sep 28 2020, 18:08

So firstly thanks for all your advice so far it is much appreciated. Well today I made some progress. Checked Magneto and think it was 180 degrees out as suggested so now set to fire at 20 degrees before TDC on compression. Cleaned and checked points set to 15 thou. New HT lead fitted(with out suppressor!!). Then gave it a try again. Managed to get it to run a few times for no more than 30 seconds before it died(note need to find and exhaust as it's seriously noisy with out one!!). Loads of fuel leaking from the bottom of the carb where the small bronze coloured plug is. Carb is set at Mixture 2 1/2 turns out, Air Reg 3/4 turn out and slow running jet 2 turns out. Tried adjusting settings but still wouldn't run for more than 30 seconds( I have stripped and cleaned carb again and checked float is Ok(also has a new needle valve and slow running jet fitted). Any ideas anyone?

by oldgit Mon Sep 28 2020, 20:10

maryalice wrote:My Lister L had a decompressor on it as standard as does my Lister M, without it they are pigs to get going let alone start, its not uncommon.

Maryalice

Thanks maryalice, my experience of stationary engines is somewhat limited, also my experience of magnetos the same.
Due to one of these posts I now see the reason for the impulse mechanism.
As a matter of interest were the Lister L and Lister M fitted with non-impulse mags?

I did once (some years ago) pick up a book on Lucas magnetos, which I was reading in a slack period at work. An engineer saw it and said he'd like to read it as he was having trouble with his vintage motorcycle magneto, so I put a book mark in and said don't lose my page and handed it to him; that's the last time I saw that book.

by maryalice Mon Sep 28 2020, 20:24

The Lister L had no impulse mechanism fitted and just to muddy the waters a little the M has a none rotary magneto called a Flick magneto which is effectively an impulse magneto Very Happy

but it doesnt rotate.

Maryalice

by Appletop Mon Sep 28 2020, 23:13

[quote="maryalice"]The Lister L had no impulse mechanism fitted and just to muddy the waters a little the M has a none rotary magneto called a Flick magneto which is effectively an impulse magneto Very Happy

but it doesnt rotate.

Maryalice [/quote]

To really muddy the waters the Wico EK has even less moving parts, only the points carrier moves on them.

by maryalice Tue Sep 29 2020, 08:03

Forgot that one.

Maryalice

by Stu Pashley Tue Sep 29 2020, 12:48

So firstly thanks for all your advice so far it is much appreciated. Well today I made some progress. Checked Magneto and think it was 180 degrees out as suggested so now set to fire at 20 degrees before TDC on compression. Cleaned and checked points set to 15 thou. New HT lead fitted(with out suppressor!!). Then gave it a try again. Managed to get it to run a few times for no more than 30 seconds before it died(note need to find and exhaust as it's seriously noisy with out one!!). Loads of fuel leaking from the bottom of the carb where the small bronze coloured porous plug is. Carb is set at Mixture 2 1/2 turns out, Air Reg 3/4 turn out and slow running jet 2 turns out. Tried adjusting settings but still wouldn't run for more than 30 seconds( I have stripped and cleaned carb again and checked float is Ok(also has a new needle valve and slow running jet fitted). Any ideas anyone?

by mattblack Tue Sep 29 2020, 12:54

Is the float height adjustable?

by Stu Pashley Tue Sep 29 2020, 13:34

mattblack wrote:Is the float height adjustable?

No can't adjust the height of the float. Can put a washer under the needle valve to lower slightly which I have done already(1mm). Float seems fine not leaking and seems to float on the bench no problem.

by maryalice Tue Sep 29 2020, 16:18

Try running the engine with the fuel cap off the tank, the air bleed maybe blocked stopping the fuel to flow.

Maryalice

by Woodsman Tue Sep 29 2020, 17:10

Got there before me Maryalice. Smile

But if it runs for 30 seconds it seems ignition side is close.

by Appletop Tue Sep 29 2020, 17:11

[quote="Woodsman"][quote="Appletop"]
Oh no you don't!!!! The Petter A1 has an impulse on the magneto and you should only need to pull it smartly over compression and not "swing it like billy-o". All the decompression lever is for it to allow you to turn the engine over for service use and is not a starting aid.[/quote]

[url=https://servimg.com/view/19972956/138][img]https://i.servimg.com/u/f31/19/97/29/56/starti10.jpg[/img][/url][/quote]

Fair enough, never used one that way, always just snapped mine over.

Was always told cranking an impulse weakened the spring.

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