| Author |
Message |
    
Rob Cook
Member
Username: rob_cook
Post Number: 4
Registered: 03-2011
| | Posted on Wednesday, May 18, 2011 - 06:27 am: | 
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Any suggestions on how I can check if the magneto for my Blaxland Twin is giving a strong enough spark?
If I wind the engine over slowly (with the spark plug out and the body earthed) I get just a little flicker. Is this enough or am I looking at having to have it overhauled?
Would appreciate any help the experienced can give.
Seems to be the only thing stopping it from running again.
Rob |
Allen Flux
New member
Username: allenf
Post Number: 1
Registered: 02-2011
| | Posted on Wednesday, May 18, 2011 - 08:05 am: |
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Don't wash the grease out of the bearings of the maggie with the wd40 unless you have to,try to spray around them .There should be a clean bright blue flashing spark. |
Greg Y
Senior Member
Username: gregoryan
Post Number: 81
Registered: 09-2004
| | Posted on Wednesday, May 18, 2011 - 10:34 pm: |
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And; don't forget that dirty breaker points can cripple the circuit, even if they look clean they can have a black oxide stuff on the contact surfaces. Use some very very fine abrasive paper, or sometimes even a piece of card will remove the black! I have often found that this has brought a long-stored maggie back to life! |
Laurie Derwent
Senior Member
Username: laurie_d
Post Number: 99
Registered: 10-2009
| | Posted on Thursday, May 19, 2011 - 07:42 pm: |
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I have found the following two methods for testing a maggy to be effecive.
Method one: Get a trusted and relaible person (wife, child but not mother in law) to hold the end of one spark plug lead and the maggy. Turn the maggy in the correct direction a turn or two and wait for any response from trusted person (no response means no spark, sudden jerking motion = healthy spark). If it is working properly and you need to conduct further tests you may need to choose a different person (random selection is a key aspect of reliablity in such such statistical research). The second way (I use it regularly) is to fit the maggy to the motor and leads to the plugs,attempt to start motor. If sucessful, run motor for required time and enjoy the day. If not, try method one.
Often the weak spark found when the plug is out is due to a poor earth between plug and motor. |
Rob Cook
Member
Username: rob_cook
Post Number: 5
Registered: 03-2011
| | Posted on Friday, May 20, 2011 - 03:30 am: |
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Thanks to Greg for the hint about the points, makes a nice big blue spark on the bench now.
Still won't start though, fuel mixture is getting through as evidenced from the spark plug after attempts to start and the magneto timing checks out.
Maybe just my jinxed lifelong struggle with 2-stroke engines.
Rob |
quinton wilkinson
Advanced Member
Username: qwilkin
Post Number: 37
Registered: 08-2009
| | Posted on Friday, May 20, 2011 - 03:50 am: |
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is spark though to plug seems odd if good spark andd timed correctly, mine starts first time every time check with Tod Vidgren on 02 43631361 he is all things ob blaxlands or phone blaxland chapman marine on 0265583182
Quinton |
neil r jones
Senior Member
Username: senojn
Post Number: 78
Registered: 08-2006
| | Posted on Friday, May 20, 2011 - 04:09 am: |
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I prefer Laurie's second method .It works every time ?
His first method I have tried (once) and I was the reliable person on the receiving end .
A friend spun it quickly while I was holding the two leads . He laughed. I dropped the magneto and smashed the rotor . I cried. Had spark then it did'nt.
Ended up giving the broken rotor Aub Rose.
It' called aversion therapy ! |
David Myers
Senior Member
Username: dave_myers
Post Number: 102
Registered: 11-2006
| | Posted on Friday, May 20, 2011 - 04:23 am: |
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Rob,
Check the mixture settings. The initial setting of the needle is 1 turn maximum from fully closed. The Air mix screw on the top of the carby should show 4 threads. Is the Air Valve spring Ok? Is the Air Valve OK?, Is the Float Ok, Not sinking?. These are all points that can affect the starting / running of the engine. The Blaxland twins are so simple to run it can't be much wrong. Are the Spark Plugs OK. They may spark all right out of the motor but under compression they may be failing. This is a common problem, especially if the plugs are Champions made in... MEXICO. They fail badly even if new. Check the above items and let us know how you go.
Mixture and Plugs are the main culprits.
Cheers,
Dave |
Rob Cook
Member
Username: rob_cook
Post Number: 6
Registered: 03-2011
| | Posted on Friday, May 20, 2011 - 07:31 pm: |
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Thanks Dave.
I will get new spark plugs, not only for this one but the Single and the "Little" Single that are following.
Will also dismantle the carburettor again and check all of those points. Did not realise the criticallity of the air valve and spring, any suggestions for sourcing new parts for them?
the eventual plan is to have a line-up of various Blaxlands in the local maritime museum so future generations can see and hear them. So need to be sure they will always run. Might even be tempted to buy a locally available Super Pup to round out the line.
Rob |
Laurie Derwent
Senior Member
Username: laurie_d
Post Number: 102
Registered: 10-2009
| | Posted on Sunday, May 22, 2011 - 07:54 pm: |
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Rob,
Have you mounted the maggy perpendicular to the line of the shaft and are you pulling the motor over in the opposite direction to the arrow? If you are starting it in the same direction as the arrow the maggy needs to be in the slot so it is not perpendicular to the shaft (i.e. the standard 'reverse' running set up). Regards Laurie |
Rob Cook
Member
Username: rob_cook
Post Number: 7
Registered: 03-2011
| | Posted on Monday, May 23, 2011 - 03:04 am: |
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Laurie,
Can you help me a little more please?
As the magneto drive was full of goop (like gunk but thicker) I dismantled it which required retiming of the magneto as the drive gear just goes onto a taper with no keyway.
I used the Blaxland manual and set the points to open at 2.25 inches before TDC (I am assuming that the mark on the flywheel is at TDC as the flywheekl was off the crankshaft when I got it and have fitted it thus) in the direction of the arrow on the flywheel.
Then I try to start it in the direction of the arrow.
Note: reversing is not important for a display engine, I just want it to run.
Rob |
Greg Y
Senior Member
Username: gregoryan
Post Number: 82
Registered: 09-2004
| | Posted on Monday, May 23, 2011 - 05:51 am: |
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I have known of at least 2 blaxlands with ther TDC mark in the wrong place. The flywheels are fitted on a keyless taper too, so they may have slipped or been installed in the wrong spot. You better confirm the real TDC with a dowel down the plug hole. In the manual it looks like the mag drive pin is aft when at TDC [?] |
Andrew Munns
Member
Username: johnoxley
Post Number: 27
Registered: 04-2010
| | Posted on Monday, May 23, 2011 - 05:09 pm: |
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To set TDC fit a trammel or fixed method for making a line on the top of the flywheel - then fit a stop at the spark plug location that will sto/measure the flywheel about 20 to 25 mm before TDC. Rotate engine forward to touch the stop and mark the flywheel. Rotate engine backwards to touch the stop and make another mark. TDC should be exactly half-way between the two marks. The hard parts on a non-keyed flywheel is firstly releasing the tapered fit and then keeping the flywheel in the right place while tightening the "nut". It might be easier to make a temporary TDC mark if needed. |
Laurie Derwent
Senior Member
Username: laurie_d
Post Number: 103
Registered: 10-2009
| | Posted on Monday, May 23, 2011 - 08:42 pm: |
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Rob, I am familiar with goop but am surprised to see it appearing on a magneto drive. Among other things it is important that the contact surface between the magneto mount and the maggy is clean to ensure a sound earth. I concur with Greg's comment of using a (clean) dowel to test for TDC of No 1 piston. Again if you are starting the motor in the direction of the arrow the maggy must be positioned offset to perpendicular. Regards Laurie |
