| Author |
Message |
    
Shane Curry
New member
Username: shane_from_jan_juc
Post Number: 2
Registered: 01-2009
| | Posted on Sunday, January 25, 2009 - 09:48 pm: | 
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Hello everyone
Please find attached a photo of my underwood single cylinder motor. This pretty little iron main'sl has been giving me dramas lately.It has been misfireing. I clamped an inductive timeing light to the spark plug lead and the misfireing is detected by the timeing light not flashing with every misfire.
However;
If I turn the motor over , with the spark plug out, via an electric drill connected to the front face of the starter pulley, I can see the spark and the timeing light flashing away without missing a beat.
Ive just had the magnito ignitor and lead replaced although the problem was occuring before that.
I tested the electric path of resistance, with my multimeter set on ohms x1, between the spark plug recepticle socket to the frame of the magnito with no resistance detectable.
Could anybody please interpret these findings
Regards - Shane  |
David Myers
Senior Member
Username: dave_myers
Post Number: 60
Registered: 11-2006
| | Posted on Monday, January 26, 2009 - 02:41 am: |
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Fit a new spark plug. The old one is breaking down under compression and failing.
Cheers, Dave |
Shane Curry
New member
Username: shane_from_jan_juc
Post Number: 3
Registered: 01-2009
| | Posted on Tuesday, January 27, 2009 - 01:22 am: |
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Thanks Dave
Went out and bought a new plug and she's now going like a dog scratching away under a table.
What threw me was I tried two plugs which I new had only two or three hours work on them but there you go.
Anyway thanks for the prompt reply seeing that I posted the message in the wrong sector
Ta - Shane |
David Myers
Senior Member
Username: dave_myers
Post Number: 61
Registered: 11-2006
| | Posted on Tuesday, January 27, 2009 - 02:42 am: |
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No Problem Shane, Glad to help.
Pretty looking set-up you have there, the hull looks great. Is the boat new or restored?
Just another tip, If the problem re-occurs with the misfiring, open the points of the maggy to about 15 thou. Most are set at 12 thou, but the dwell is too short for the flux to build up in the coil windings and you do not get a 'hot' spark, hence the plug will misfire under load. Just a thing to look out for.
Happy boating,
Dave |
Shane Curry
Member
Username: shane_from_jan_juc
Post Number: 4
Registered: 01-2009
| | Posted on Tuesday, January 27, 2009 - 09:59 pm: |
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G'day Dave
That tip with the maggy points may be just what I am looking for because the problem first appeared intermitantly under load. I'll hopefully take her out on the weekend and test it out.The dinghy's hull is cold moulded mahogany which I restored a few years ago.That boat in your ID box looks interesting, is it a snapper boat?
Here's a couple of extra photos
All the best - Shane
  |
Bruce Findlay
Advanced Member
Username: bruce_findlay
Post Number: 48
Registered: 03-2006
| | Posted on Tuesday, January 27, 2009 - 10:18 pm: |
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Dave, thanks for that maggy points gap tip, that might come in handy one day. I'll lock it away in my limited memory bank.
Shane, what a beautiful little boat and motor. I'd love to see her in the flesh one day. When are you going to drag her up to NSW for us to have a look at?  Bruce, |
Eric Schulz
Advanced Member
Username: eric_schulz
Post Number: 48
Registered: 01-2007
| | Posted on Wednesday, January 28, 2009 - 04:05 am: |
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Shane, I am surprised nobody has commented about your engine. If I am not mistaken, that is a rare model Underwood.
All the illustrations and engines I have seen have an enclosed flywheel, with the magneto attached to the flywheel cover. I have seen one engine with the magneto drive from the other end of the crankshaft and one direct driven from the end of the crank.
Your magneto looks to to have a chain drive, whereas they mostly had an eccentric on the crankshaft that operated a link to an arm on the armature shaft. This gave an oscillating motion to the magneto.
Does that muffler belong to that engine? I had not seen one like that on an Underwood.
Eric
This is a more usual design. |
Todd Vidgen
Senior Member
Username: todd_vidgen
Post Number: 111
Registered: 03-2008
| | Posted on Wednesday, January 28, 2009 - 03:43 pm: |
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I believe the muffler is a Blaxland unit
Also one thing to remember when you increase
the points gap, you also advance the timing,so
consideration should be given to resetting the
cam on the magneto |
Shane Curry
Member
Username: shane_from_jan_juc
Post Number: 5
Registered: 01-2009
| | Posted on Friday, January 30, 2009 - 05:10 am: |
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Thanks for the compliment Bruce, I would love the opportunity to explore some of NSW's rivers and esturies which are few and far between here on the West coast of Vic.
And Eric, with your question on the magnito drive, it's type with the eccentric on the crankshaft with link arm rocking a keyed receptical for the maggy. The muffler is a Blaxand unit
Thanks for your input too Todd, the timing is a thing thats easily adjusted on this motor, just a matter of backing off that wing bolt and tilting the body of the maggy.
Shane |
Eric Schulz
Advanced Member
Username: eric_schulz
Post Number: 49
Registered: 01-2007
| | Posted on Friday, January 30, 2009 - 11:16 pm: |
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Shane, I tried sending you an e-mail, but the address in your profile does not work.
My question was would it be possible to get another photo or 2 showing the magneto side and the drive end?
Thanks in advance.
Regards,
Eric |
