Testing Honda GX340 generator ignition coil

[elliott194]

Hello, can anyone give me advice on deciding whether this coil is good or not please? It’s quite rusty and I have no spark...

The problem is I cannot find any resistance values for this model coil...

The Honda part number is 30500-ze3-003

The primary windings were 0.25 Ohms, the secondary windings were 4.53 Ohms.

Both readings are lower than other differently designed ignition coils for small Honda engines. I can buy a new coil but they are very expensive (£100) and no returns!

 

[DPG]

The coil readings will always be slightly different. How much are they different?

What about a non-OEM replacement?

Edit, might have got the wrong link here but you get the idea

WOOSTAR Ignition Coil Assembly Replacement for GX120 GX140 GX160 GX168 GX200 5.5HP 6.5HP Engine Generator Lawn Mower : Amazon.co.uk: Garden & Outdoors

WOOSTAR Ignition Coil Assembly Replacement for GX120 GX140 GX160 GX168 GX200 5.5HP 6.5HP Engine Generator Lawn Mower : Amazon.co.uk: Garden & Outdoors

www.amazon.co.uk

 

[Lucien Nunes]

the secondary windings were 4.53 Ohms

If it really is.4.5Ω then it's shorted, but it seems an unlikely figure. Are you sure it's not 4.5kΩ? That would be reasonable, although tbe coil could still be faulty in other ways.

 

[elliott194]

The coil readings will always be slightly different. How much are they different?

What about a non-OEM replacement?

Edit, might have got the wrong link here but you get the idea

WOOSTAR Ignition Coil Assembly Replacement for GX120 GX140 GX160 GX168 GX200 5.5HP 6.5HP Engine Generator Lawn Mower : Amazon.co.uk: Garden & Outdoors

WOOSTAR Ignition Coil Assembly Replacement for GX120 GX140 GX160 GX168 GX200 5.5HP 6.5HP Engine Generator Lawn Mower : Amazon.co.uk: Garden & Outdoors

www.amazon.co.uk

Hi DPG, these are the normal values for similar coils...

GX120 - GX160 Honda engines, the secondary resistance value should be in the region of 5.9 - 7.1 kΩ.
Mine 4.5kOhms

GX120 - GX160 Honda engines, the primary resistance value should be in the region of 0.8 - 1.0 Ω.
Mine 0.25 kOhms

 

[elliott194]

If it really is.4.5Ω then it's shorted, but it seems an unlikely figure. Are you sure it's not 4.5kΩ? That would be reasonable, although tbe coil could still be faulty in other ways.

Hi Lucien, well i'm probably using the multimeter wrong... I had the setting on 20k

 

[Lucien Nunes]

On a 20kΩ range the resistance must be 4.53kΩ, as the display would read up to 19.99kΩ in increments of 0.01kΩ = 10Ω. In which case unless you have a reference figure for that coil that is different I would say it's probably OK for continuity. The insulation might be faulty though, which often only shows up when actually producing a spark (or not) due to flashover.

 

[brianmoooore]

Resistance measurements on the secondaries of these kinds of coil are of limited value. A few turns of the coil shorted out will stop it working without any noticeable reduction in resistance.

 

[Lucien Nunes]

Indeed. Like TV line output transformers, where the resistance might be correct to within any reasonable tolerance and giving no sign of insulation failure, arcing or corona. The shorted turns can only really be discovered by ringing the transformer with a test waveform.