Petter A1 Starting Issues
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maryalice
Woodsman
oldgit
Stu Pashley
Gaudin98
Robotstar5
tony RA
11 posters
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Petter A1 Starting Issues
Today I tried starting up my Petter A1 for the first time. Turned over but nothing. Fuel in the Carb and took the plug out and checked and a good blue spark at TDC. When I turn it over then stop it blows a fair bit of fuel out of the strangler(it's a Zenith 24T2 Carb which has been pretty much completely rebuilt) Strangler is spring loaded closed(is this correct, I have tried with it open and closed but no joy). Anyone any ideas(thought maybe a float issue)
Stu Pashley- Born to be wild
- Posts : 29
Join date : 2020-07-06
Re: Petter A1 Starting Issues
The choke butterfly should be spring loaded open and closed to start may have been assembled wrong
good luck with it Tony
good luck with it Tony
tony RA- A credit to the forum
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Age : 77
Location : newtown powys
Re: Petter A1 Starting Issues
As above, choke should be sprung in the open position, also check it's not flooding, I had to put an extra washer under the needle seat to lower the fuel level in the float bowl as it would drip fuel out the mouth.
Try a bit of fuel in the plug hole, if it fires it will prove the timing/mag are OK which just leaves the carb.
Try a bit of fuel in the plug hole, if it fires it will prove the timing/mag are OK which just leaves the carb.
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Stuart
Robotstar5- Life Member
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Join date : 2018-09-25
Re: Petter A1 Starting Issues
Thanks. I will sort choke so it is spring loaded open!!. Also going to strip down carb as suspect may also have a stuck or leaky float so will check and as you say may add a washer under the needle. Any advice regarding carb settings. How about the slow running jet should this be fully in or out some turns? Will try the fuel down the plug hole to confirm it is a carb issue not a spark issue.
Stu Pashley- Born to be wild
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Join date : 2020-07-06
Re: Petter A1 Starting Issues
Try screwing slow running jet fully in, don't overtighten, then open a couple of turns.
Have manual. PM me if you need a copy.
Have manual. PM me if you need a copy.
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Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman- Admin
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Re: Petter A1 Starting Issues
Many Thanks just PM'd you.Woodsman wrote:Try screwing slow running jet fully in, don't overtighten, then open a couple of turns.
Have manual. PM me if you need a copy.
Stu Pashley- Born to be wild
- Posts : 29
Join date : 2020-07-06
Re: Petter A1 Starting Issues
Woodsman wrote:Try screwing slow running jet fully in, don't overtighten, then open a couple of turns.
Have manual. PM me if you need a copy.
For the A1 or the Zenith carb?
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Stuart
Robotstar5- Life Member
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Re: Petter A1 Starting Issues
Robotstar5 wrote:Woodsman wrote:Try screwing slow running jet fully in, don't overtighten, then open a couple of turns.
Have manual. PM me if you need a copy.
For the A1 or the Zenith carb?
For the Carb if possible. Have a manual for A1. Thanks
Stu Pashley- Born to be wild
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Join date : 2020-07-06
Re: Petter A1 Starting Issues
Stu Pashley wrote:Robotstar5 wrote:Woodsman wrote:Try screwing slow running jet fully in, don't overtighten, then open a couple of turns.
Have manual. PM me if you need a copy.
For the A1 or the Zenith carb?
For the Carb if possible. Have a manual for A1. Thanks
I have a carb "manual" (only a few pages), if @Woodsman doesn't send you one, drop me a PM with an e-mail address and I will send it.
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Stuart
Robotstar5- Life Member
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Re: Petter A1 Starting Issues
Manuals sent.
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Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman- Admin
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Re: Petter A1 Starting Issues
Woodsman wrote:Manuals sent.
Many thanks for that.
Stu Pashley- Born to be wild
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Join date : 2020-07-06
Re: Petter A1 Starting Issues
So stripped the carb down and all looks ok. Float seems fine. If I take the spark plug out and turn over I have a good blue spark at TDC. I have taken the end cap off the magneto to have a look at the points. If I start at TDC(Magneto just fired and key way at bottom).As you rotate the flywheel, once you rotate through around 270 degrees the points begin to close then the central shaft seems to stop rotating even though you are still rotating the flywheel before it then clicks over on impulse. If I then rotate flywheel backward approx 20 degrees the points open. Is this correct as currently at a bit of a loss. I did also try dropping some fuel down the plug hole and a bit of pencil graphite on the plug and did get a nice flame out the exhaust so guess must have sparked.
Stu Pashley- Born to be wild
- Posts : 29
Join date : 2020-07-06
Re: Petter A1 Starting Issues
The magneto will stop rotating while the impulse engages.
I ask this every thread about engines not running.... but have you taking a resistance reading from the HT lead to earth (Magneto body, cylinder head bolt etc)?
I ask this every thread about engines not running.... but have you taking a resistance reading from the HT lead to earth (Magneto body, cylinder head bolt etc)?
StuartTurnerSteve- Life Member
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Re: Petter A1 Starting Issues
StuartTurnerSteve wrote:The magneto will stop rotating while the impulse engages.
I ask this every thread about engines not running.... but have you taking a resistance reading from the HT lead to earth (Magneto body, cylinder head bolt etc)?
Just checked from Plug cap end of HT lead to earth is 0.02 M Ohms.
Stu Pashley- Born to be wild
- Posts : 29
Join date : 2020-07-06
Re: Petter A1 Starting Issues
Points are closing just before TDC should they be opening just before TDC? If so how do you correct?
Stu Pashley- Born to be wild
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Join date : 2020-07-06
Re: Petter A1 Starting Issues
Should be opening at tdc with the impulse, it will automatically advance the timing.
StuartTurnerSteve- Life Member
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Re: Petter A1 Starting Issues
So is that the problem the points are closing before TDC rather than opening even though impulse is firing at TDC. Anyone know how I correct this?
Stu Pashley- Born to be wild
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Join date : 2020-07-06
Re: Petter A1 Starting Issues
The mag is fitted 180 degrees out.
Gaudin98- Expert
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Age : 55
Location : Lancashire
Re: Petter A1 Starting Issues
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 openingGaudin98 wrote:The mag is fitted 180 degrees out.
Stu Pashley- Born to be wild
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Join date : 2020-07-06
Re: Petter A1 Starting Issues
Magneto should 'fire' at 20 degrees before TDC. Slowly turn engine over compression. The impulse should click just before TDC. Loosen the bolts and rotate magneto to adjust timing - anticlockwise to advance. You could mark flywheel and body when at TDC, then measure circumference with tape - divide by 360 and multiply by 20 to give offset from TDC.
Good luck
Good luck
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Regards Paul
Tha can alus tell a Yorkshireman - but tha can't tell him much.
Woodsman- Admin
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Re: Petter A1 Starting Issues
So at a bit of a loss. Magneto tweaked and now firing at 20 Degrees before TDC(Thanks Woodsman) and giving a good blue spark. Put the spark plug back in and try to turn over and still nothing. Points open after impulse then close again just before impulse, is this correct? Have checked the Carb and that all seems OK. Checked resistance of the HT lead and measured 15 K ohms(is this OK). There is a suppressor cap fitted, I know some say not to have these on a Magneto engine. I know I must be missing something just don't know what.
Stu Pashley- Born to be wild
- Posts : 29
Join date : 2020-07-06
Re: Petter A1 Starting Issues
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.
15k ohms sounds high, 3-7KOhms is what I tend to look for. Pull the suppressor cap off.
StuartTurnerSteve- Life Member
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Join date : 2020-01-02
Re: Petter A1 Starting Issues
As told by my magneto repairer, Bin the suppressor they bugger magneto's.
Maryalice
Maryalice
maryalice- Life Member
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Re: Petter A1 Starting Issues
From what you say it seems to be failing under compression? Maybe the coil has a break in the wiring which can jumped when the plug is in air but not when under pressure. What is the resistance of the coil
Apologies just spotted that you have already measured coil resistance.
I'd be tempted to attach any old piece of stranded wire to magneto and use gloves, insulated priers, or numpty to hold the other end about 6mm from 'earth' and give it a whirl. If you get a decent spark try attaching to plug and give another go.
Just for interest - a nice description of the impulse mechanism here:
https://www.flight-mechanic.com/the-fadec-system-impulse-coupling/
Apologies just spotted that you have already measured coil resistance.
I'd be tempted to attach any old piece of stranded wire to magneto and use gloves, insulated priers, or numpty to hold the other end about 6mm from 'earth' and give it a whirl. If you get a decent spark try attaching to plug and give another go.
Just for interest - a nice description of the impulse mechanism here:
https://www.flight-mechanic.com/the-fadec-system-impulse-coupling/
Woodsman- Admin
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Re: Petter A1 Starting Issues
Woodsman wrote:From what you say it seems to be failing under compression? Maybe the coil has a break in the wiring which can jumped when the plug is in air but not when under pressure. What is the resistance of the coil
Apologies just spotted that you have already measured coil resistance.
I'd be tempted to attach any old piece of stranded wire to magneto and use gloves, insulated priers, or numpty to hold the other end about 6mm from 'earth' and give it a whirl. If you get a decent spark try attaching to plug and give another go.
Just for interest - a nice description of the impulse mechanism here:
https://www.flight-mechanic.com/the-fadec-system-impulse-coupling/
No I had only tested resistance of HT lead. But have since ditched the suppressor cap and this is now down to 5 K Ohms so may make up a new HT lead.
I have tested the coil. If I go from Magneto Body to the tab on the coil it's 5 k ohms. If I disconnect the LT coil lead and condenser and test it between Magneto body and LT Lead I get 5 ohms used 2 multi meters and have the same readings with both.
Stu Pashley- Born to be wild
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Join date : 2020-07-06
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