Calling all Petter M experts

- P
- Pete Aldous
  
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posted
18 years ago

Sat, Jul 19, 2003 5:39 PM

I have bought a 1934 1.5 hp Petter M (you remember, the one on Ebay with the
serial no plate held on with cross head screws yuk!).
Anyway, more out of interest, I mailed him to find out what he really wanted
for it and it transpired that the guy put a reserve of £350 on it, and it
only reached £226. He was going to offer it to the highest bidder but....it
would not start anymore. Seems it runs for a couple of minutes, and then
stops. He messed around, could not fix it and gave up.
Anyway, to cut a long story short, I made him an offer, as it stood, and he
accepted. So, I get it home, and it starts, and runs for a couple of
minutes, perfectly (weakening it off gives the usual pops and bangs that the
public likes) and then just stops.... just like turning the mixture screw
shut or shorting the plug lead.
It has a spark, timing OK. and I have stripped the carb, cleaned everything
I can find and it starts and runs again....and then stops. I have gad the
air plate off the crankcase and it looks OK, I have had the "fuel pump"
plate off, checked it and it seems OK.
I have run out of ideas guys so, anyone got any suggestions?
Thanks.

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- campingstoveman
  
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posted
18 years ago

Sat, Jul 19, 2003 5:53 PM

I think this is a job for "Super Petter" sorry Roland could not resist :-))
Martin P
Pete Aldous wrote:

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- Pete Aldous
  
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posted
18 years ago

Sat, Jul 19, 2003 8:41 PM

Thanks for that Roland, I have had the foot valve out, sucked (uurrgghh) and then blown and it seemed to seal, likewise the ball valve on the pump union but I have not stripped them down yet. The really strange thing is that when it stops, no amount of topping up the carb will get it going for at least an hour which sugested the mag, so last time it stopped, I whipped the plug lead of and held it against the engine which produced a spark right down to the last rev!!!
Yes, John Southall is round here now and remarked that his Petter did not have the finials that this has....looks like they are off a coffin!!!!
Going out tommorrow so I guess it will be Monday before I get another chance to look at it, thanks again.
Pete Aldous

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- Peter A Forbes
  
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posted
18 years ago

Sat, Jul 19, 2003 8:54 PM

Sounds like a vapour lock in the carb or the fuel line, is that getting really hot for any reason ? try cold wet cloths on the piping before it stops and see if that keeps it running.
I recall the Rover 3500 cars (2000 shape with the 3.5 V8) that had the fuel lines running inside the prop tunnel with the exhaust.....
Peter
-- Peter & Rita Forbes snipped-for-privacy@easynet.co.uk Engine pages for preservation info:

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- R
- Roland and Celia Craven
  
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posted
18 years ago

Sat, Jul 19, 2003 9:27 PM

Most unlikely. Mine ran all last weekend at a water temp of 180-200f. My experience is that the suck/blow test is not a reliable guide to future performance :-) Next step is to remove the carb and check the distance from end of jet to piston (using a depth gauge to achieve Sounds like a vapour lock in the carb or the fuel line, is that getting really

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- P
- Pete Aldous
  
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posted
18 years ago

Sun, Jul 20, 2003 8:36 PM

An update, aimed at Roland really.
Foot valve definately OK (held fuel up for 24hrs) as is the valve in the fuel pump union. Disconnecting bent fuel pipe from that union and the carb and turnin over produces fuel proving the pump works. Checked distance of jet to piston and it was a bit to big so I adjusted it as best I could, but stangely, there is not enough thread to get it to 1/16th also, you are right about the ball, it is steel, but having said all that, it has run, and perfectly when it did.
Not that happy with the fuel level as it seems lower than specified but it is fixed, right, by the little holes in the rod that you pull up to drain the fuel from the carb.
So late this evening, I am back to suspecting the mag, as I cannot get a spark out of a few odd D16s that were laying about, but I can from an Champion A6 and a Champion 7 but as soon as I turn the engine over, it soaks the plug with fuel. Tomorrow, I will try a plug from a working engine, but for now, I am kn******d, where is that Whisky bottle.
Incidentally Roland, what plug should the little begger take?
Pete Aldous

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- Pete Aldous
  
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posted
18 years ago

Sun, Jul 20, 2003 8:40 PM

Roland,
I am forgetting my manners with the last post, I should have started it with thanking you for your help so far, frustration setting in I guess. Thanks again.
Pete Aldous

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- J K Siddorn
  
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posted
18 years ago

Mon, Jul 21, 2003 12:27 PM

No Petter expert me, but it does sound like an ignition problem OR primary compression - but I'll leave the latter to wiser heads than I ;o))
I think I'd make sure the plug lead has a copper core. If so then ;-
A.) swap the mag for another if available. If not, fit a specially made up cheap plastic copper cored plug lead with a bit of wire (pop rivet ends are perfect) shoved into the ends of two short lengths. Join them by sliding a bit of plastic pipe over them, separating the two ends by a plug gap so you can see the running spark. Get a coffee, start it up and sit and watch the spark. If it falters, you'll be able to see it without disturbing it. B.) If 14mm, fit a brand new plug with an extended nose - so long as the piston doesn't hit it. If not, reduce the plug gap by half. C.) reduce the points gap by a few thou
These are only empirical diagnostic exercises, naturally, intended to track down the errant part.
Regards,
Kim Siddorn.

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- Pete Aldous
  
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posted
18 years ago

Mon, Jul 21, 2003 7:48 PM

Thanks for the input Kim, your idea regarding checking the spark between lead and plug produced NO SPARK so I suspect the mag is breaking down under load.
Has anyone got a BTH type M1-AF4 for a Petter M please?
Pete Aldous

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- J K Siddorn
  
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posted
18 years ago

Mon, Jul 21, 2003 10:00 PM

"Pete Aldous" wrote
Thanks for the input Kim, your idea regarding checking the spark between lead and plug produced NO SPARK so I suspect the mag is breaking down under load.
Has anyone got a BTH type M1-AF4 for a Petter M please?

Silly question time. Don't shout at me ...............
Have you cleaned and gapped the points?
Removed the pickup brush holder and given the slip ring/brush holder a wipe with a meths soaked rag?
Removed the points baseplate and checked to see that the earthing brush is touching the surface beneath it/is present!
Regards,
Kim Siddorn.
PS. The ST P3 now runs backwards having reversed the timing to suit the new magneto. Did you notice the trail of first class cast iron weld on one of the feet? somne of the best work I've seen. Also, I suspect that the side has been frosted out of the cylinder long ago, but it is so well cleaned up that I'm not certain yet. It starts so easily I'm looking forward to getting it up together with its dynamo. ;o))

- P
- Pete Aldous
  
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posted
18 years ago

Tue, Jul 22, 2003 7:15 AM

Yes, done all that, I will probably pull the mag apart to see if there is any other problems with the condenser perhaps.
Glad that work on the ST is going well, I had noticed the weld on the foot, but not the side of the cylinder, look forward to some pics of it doing some work with the dynamo.
Still think I need a mag........
-- Pete Aldous

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