Yerf-Dog cranks no spark no start

[joesplace_383]

i have a yerf dog rover 400cc that will not start cranks but it has no spark have replaced the stator and crank sensor ignition switch and cdi box and coil still no spark im getting the ground trigger from cdi box but no power to the coil with ignition on cannot find a wiring diagram that matches up to this unit all the parts were bought from amazon Japanese parts supplier. any help on this or theory of operation of ignition system would be great thanks

 

[Master Hack]

Probably the reason it wont start is cuz it has no spark. I think the two are related some how. I would srart by fixing the spark.

sadly you haven't given any worthwhile information, so nobody here can help.
at bare minimum you are going to need some basic electrical trouble shooting skills.
continuity testing every wire would be a good next step.
lacking the above mentioned skill, you better take it somewhere.

 

[Thepartsguy]

No real helpful info given as said above. Is that an ac or dc system? Did you buy an amazon ac or dc cdi box? ground to the coil? The cdi has one wire that goes to the coil and the other post is a toggle switch to ground to shut off spark.

Watch Harvey spooners portable cdi videos on YouTube and you will see a gy6 ignition is actually very well thought out and simple. By adding one wire you swap from an ac to dc cdi box or vise versa. gy6 ignitions fit ALMOST ANYTHING.. I have a cdi box purchased in 2024 on a Kawasaki from 1986 and a briggs from 1978 so the sky’s the limit.

 

[Rat]

i have a yerf dog rover 400cc that will not start cranks but it has no spark have replaced the stator and crank sensor ignition switch and cdi box and coil still no spark im getting the ground trigger from cdi box but no power to the coil with ignition on cannot find a wiring diagram that matches up to this unit all the parts were bought from amazon Japanese parts supplier. any help on this or theory of operation of ignition system would be great thanks

ALWAYS, ALWAYS, ALWAYS!!
Check, fuses, wire continuity, and connectors BEFORE replacing anything EVER!

You're doing nothing but wasting money and time while "Throwing $hit at the walls to see what sticks"... a method best reserved for AFTER an exhaustive effort of checking, researching, and researching everything that can, will, or might be the cause.

9/10 It will always be A loose, dirty, or broken connection or a bad wire. It only takes an abraded or melted wire laying against anything that conducts a ground to shut down or fry a CDI or other electrical component including blowing fuses as fast as you can turn the key after replacing.

stators in particular almost never go bad (when they do it is absolutely always a side effect of the real problem)

CDI, crank sensors, ignition triggers, and ignitor coils... do go bad but not as often as spark plugs or spark plug wires. Most times if they are completely dead it is again a side effect of a larger issue... generally speaking a short to ground, or a faulty VRR module allowing overvolt conditions which will USUALLY (but not always) fry the battery before any other significant harm comes to the system.

In a no spark situation the first thing I always check regardless of what engine or how many cylinders it has IS the HT (High tension aka spark plug wire) connections with the coil and cap.

Very often they are loose and can be fixed by clipping 1/4" off each end and reattaching, or the wire itself is worthlessly age and heat deteriorated and needs replaced entirely.

Ignitor coils, CDI's, can be bench tested with a Multimeter, I'm fairly sure crank position sensors and ignition tiggers can as well.

 

[joesplace_383]

No real helpful info given as said above. Is that an ac or dc system? Did you buy an amazon ac or dc cdi box? ground to the coil? The cdi has one wire that goes to the coil and the other post is a toggle switch to ground to shut off spark.

Watch Harvey spooners portable cdi videos on YouTube and you will see a gy6 ignition is actually very well thought out and simple. By adding one wire you swap from an ac to dc cdi box or vise versa. gy6 ignitions fit ALMOST ANYTHING.. I have a cdi box purchased in 2024 on a Kawasaki from 1986 and a briggs from 1978 so the sky’s the limit.View attachment 146076View attachment 146077

this is a dc system and ill attach more pictures

 

[joesplace_383]

this is a dc system and ill attach more pictures

unit has no spark that is why it will not start im trying to diagnose why it does not have spark checking wires to the coil there is 2 wires one is a ground trigger to activate coil the other wire if im corrrect the other wire should have 12 volts to it with the ignition on but it doesnt

info on unit: Yerf-Dog CUV Rover #34800 & #34801

•​

10 HP single cylinder engine​

4-Stroke, air-cooled, OHV, OHC,​

 

[Thepartsguy]

you need to look at the listing you purchased the dc cdi through. It should have come with a diagram. If you wire this stuff wrong it can make a bang so just use caution.

 

[joesplace_383]

you need to look at the listing you purchased the dc cdi through. It should have come with a diagram. If you wire this stuff wrong it can make a bang so just use caution. View attachment 146196

on the diagram the pin that provides pulse is that dc to the coil and how can i accurately check that

 

[Thepartsguy]

on the diagram the pin that provides pulse is that dc to the coil and how can i accurately check that

The pin on the diagram above labeled pulse goes to the red wire on pickup trigger. The white wire on pickup goes to ground.

Are you trying to convert from AC to DC because that can be slightly confusing.

The wire on the diagram that says to ignition coil goes to the green post on the coil. The coil will have one ground post you can add a switch to to shut off spark.

 

[Thepartsguy]

Ground
Pulse
Coil
12v positive

The two ground wires go to ground.

DC ignition power black wire from cdi goes to + terminal of 12v battery

You can see my BLUE pulse wire from CDI connected to the RED wire of the pulse trigger with a wire cap. The other WHITE wire off the trigger goes to ground.

You can see the green wire from CDI goes to the green post sticking off the coil.

You might have two posts a green AND a black post sticking off the coil. THE CDI WIRE MARKED TO IGNITION COIL GOES TO THE GREEN coil post.

 

[Timf1981]

Was a solution ever found?

People throw parts at stuff because willing knowledgeable people are not easy to find. And because gy6 parts are cheap on Amazon

If you have never worked on a 38400 yellow Yerf-Dog. Be careful of the advice you give. The starter switch is a little unusual. The correct/ original stator has 3 wires going to a square 4 plug and a separate blue/white trigger wire. It is a d/c system. And the cdi 2 wire connector has a brown wire to each pin. I don't totally understand the brown wires. I believe they come from the ignition switch. There is no kill button. The ignition switch act as the kill switch.
I have yet to locate an actual 38400 Yerf-Dog wiring diagram.
BMI lists a dc cdi for the Yerf-Dog at $61 I don't know it it is wired slightly different. In another post someone needed to remove one of the brown wires from the cdi to get it to have spark. With both brown wires in place. They would only get one spark. I can't remember if it got one spark when the key was first turned to the on position or when the key was turned to energize the starting

 

[Edwin Spangler]

Was a solution ever found?

People throw parts at stuff because willing knowledgeable people are not easy to find. And because gy6 parts are cheap on Amazon

If you have never worked on a 38400 yellow Yerf-Dog. Be careful of the advice you give. The starter switch is a little unusual. The correct/ original stator has 3 wires going to a square 4 plug and a separate blue/white trigger wire. It is a d/c system. And the cdi 2 wire connector has a brown wire to each pin. I don't totally understand the brown wires. I believe they come from the ignition switch. There is no kill button. The ignition switch act as the kill switch.
I have yet to locate an actual 38400 Yerf-Dog wiring diagram.
BMI lists a dc cdi for the Yerf-Dog at $61 I don't know it it is wired slightly different. In another post someone needed to remove one of the brown wires from the cdi to get it to have spark. With both brown wires in place. They would only get one spark. I can't remember if it got one spark when the key was first turned to the on position or when the key was turned to energize the starting

I would have never thought a Yerf-Dog came with a GY6... -Or am I just confused?

 

[Hellion]

I would have never thought a Yerf-Dog came with a GY6... -Or am I just confused?

I bet JimD would know. But I’m with you, thought they had the usual industrial engine and TC arrangement.

[EDIT]: this is not the usual Yerf-Dog. This is a utility vehicle that needs F-N-R to be of any real utility. Such a vehicle is basically beyond the forum’s purview. But we take all kinds here, unlike the Mos Eisley cantina, and the GY6 is common on karts/buggies…

 

[Edwin Spangler]

I bet JimD would know. But I’m with you, thought they had the usual industrial engine and TC arrangement.

[EDIT]: this is not the usual Yerf-Dog. This is a utility vehicle that needs F-N-R to be of any real utility. Such a vehicle is basically beyond the forum’s purview. But we take all kinds here, unlike the Mos Eisley cantina, and the GY6 is common on karts/buggies…

Oh yea I see now. Guess the pic didnt show at first.

 

[Sparkwizard]

When I read "400cc", I do not think about GY6. Maybe I've been under my rock too long.

 

[Edwin Spangler]

When I read "400cc", I do not think about GY6. Maybe I've been under my rock too long.

Lol that Tim fella got us all confused. Should remove any mention of GY6...