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Old 21 December 2013, 04:59   #41
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Fit like Simon, didnae realise you were a Stoney loon!! I'll have to get in touch next time I bring the Rib up.
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Old 21 December 2013, 05:07   #42
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I think the lack of spark is the first port of call. Also check the carb has all the parts inside, check against a parts list. I had a yammie once missing a rubber plug inside the carb which let heaps of fuel into the bore causing serious flooding. Fuel pump can also do this, but you have checked it.

Lastly, if you end up with a wet plug and a good blue spark, I would look at the condition of the bores, coked in rings from over oiling or a bottom crank seal. A bust crank seal usually gives a red colour on the plug.

A good way to test for a strong spark is to insert a screwdriver into the cap and cable tie the shaft up to an inch from the block, a strong spark will Jump 1-2 cm. if not, it's clearly the first problem to sort out.
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Old 21 December 2013, 14:54   #43
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Right, the woodruff key is fine.

I've ordered a CDI unit, and will let you guys know if this solves the problem.

In other news, I bought an old seagull, stripped, cleaned, painted and rebuilded it. Started ok the third pull today!



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Old 23 December 2013, 15:08   #44
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and the plot thickens....

Changed the CDI unit and it made no difference. I did however, notice that if i hold the spark plug next to a bolt, the spark jumps from the electrode to the bolt, but not across the plug itself. If i reduce the gap to about .025" on the plug, it sparks as you would expect it to at .040". So it appears that I am not getting a strong enough spark. So where do I look first with that? magneto? Coil? HT lead?

Please note, this is the same with the old plug, and the brand new one.

Cheers

Si
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Old 23 December 2013, 16:36   #45
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I would do the easy things first, Check earths on the coils, renew the plug leads, check other earths on the block.

HTH.
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Old 23 December 2013, 16:42   #46
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Try the screwdriver trick. Find out how far you can move a screwdriver from the bolt. I also assume the recommended plug is being used?

I've not seen what you are describing happen before. It usually looks ok at the plug, but won't jump a larger gap.

Also maybe try without the plug cap and use a terminal, if bit is a resistor cap, there could be too much resistance.
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Old 23 December 2013, 18:37   #47
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By pass the kill cord i had a dodgy one.. use some ht testers to see if your sparking onto the plug from the coil
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Old 23 December 2013, 18:52   #48
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RIBase
Cut your losses, sell it to me for pennies and start afresh.
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Old 24 December 2013, 03:04   #49
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The spark might already be jumping a gap...what is the ohms reading of the spark plug wire? Hopefully it is not open. Throwing parts is not the right way to perform diagnostics. Testing then replacing the bad part is.
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Old 24 December 2013, 04:10   #50
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Can't remember the resistance of the HT lead but it was low.

In fairness, everything seems fine with the engine, so why not replace one component at a time until it works?
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