K-750 timing and 6V elec. ignition

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mitcheman
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K-750 timing and 6V elec. ignition

Post by mitcheman » Mon Jul 22, 2019 5:33 am

Hi guys,

I hope you can help me. I have got a Dnepr K750 with a 6V elec. ignition. I've had to replace my previous elec. ignition because it shorted out :-(.

Now my issue. I have the ignition with the LED on it. But now the timing. I have no hole to check the timinig so I cannot check BTDC.

What is the propper way to set this up? I know I need to pop the end cap off and check the piston travel and set it to 9mm before the end of the stroke. But what do I on the rotor? Do I need to put it before the cotact so it's (the LED) about to come on or does it need to be on (the LED)?

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propwash
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Re: K-750 timing and 6V elec. ignition

Post by propwash » Mon Jul 22, 2019 9:09 am

What ignition?
Does the electronic ignition instructions state to set at, BTDC or TDC?
As you probably know, normally, the flat heads are set to have the points open at BTDC - approx 34-36 deg, which translates to 9mm BTDC as measured at the cylinder.
Some electronic ignitions are set at TDC. This would only require a dowel to determine TDC.

mitcheman
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Re: K-750 timing and 6V elec. ignition

Post by mitcheman » Mon Jul 22, 2019 11:52 am

I would like to know when my sparkplug needs to fire. Is this at 9mm btdc or at tdc? She is running currently but nog good. Backfires, gets hot does not idle without chocke and sounds slow when I rev it.

Got this set: https://m.ebay.nl/itm/K750-6-volt-Micro ... Sw5utabhi7

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propwash
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Re: K-750 timing and 6V elec. ignition

Post by propwash » Mon Jul 22, 2019 1:22 pm

Standard points -
Points should open (plug fires) at 36 deg BTDC or 9mm as measured from the top of piston travel. This is about the only way to set since there are generally no markings on the flywheel and no peep hole in case.
The lever on the handlebar is a manual retard lever used when starting the engine.

I don't know anything about the electronic ignition you have linked. However, it looks similar to the Type 3 many use on OHV engines. These are set at the fire position (9mm BTDC in your case) and the rotor placed such that the rotor line is between the +10 and -10 marks. You will also want to re-gap your plugs to approx 1mm. This should be a starting point.

mitcheman
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Re: K-750 timing and 6V elec. ignition

Post by mitcheman » Mon Jul 22, 2019 1:50 pm

Okay checkee the setup and it seems fine. But the sparks looks a bit weak to me... gap is 1 mm? Damn. Gotta check that. Saw that the battery was low ish on acid. Filled it and hooked a charger up.

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Re: K-750 timing and 6V elec. ignition

Post by propwash » Mon Jul 22, 2019 2:55 pm

0.8-1.0mm will work for plug gap.

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