Welcome to this week’s tech talk at Venom Motor Sports!
Often customers ask me about spark plugs. So today we are going to spend some time answering common spark plug questions.
Please click on our “Spark Plug” video link below to view our testing procedures and comparisons of actual spark plugs on our Venom 125 cc ATV.
Keep in mind that this information applies to all of our fine gas powered Super Pocket Bikes, Dirt Bikes and ATVs!
Ok onto this week’s topic.
Tim...how does a “spark plug” produce a spark?
Spark plugs produce a spark by forcing a high voltage electrical charge to jump across an air gap. The electrical energy comes from the ignition coil and is a very high direct current voltage charge.
The electrical charge runs from the top of the spark plug right down the center electrode in the spark plug body and then jumps across the air gap from the center electrode to the ground tip, producing spark. The ground tip is attached to the metal body of the spark plug just below the spark plug threads.
Installing a High performance “CDI” will increase the size of the spark produced by any spark plug. More spark equals more kaboom in the engine cylinder and better engine performance. Yes, you can order a new high performance “CDI” from us here at Venom Motor Sports.
Tim...how can I check to see if my spark plug is working?
That is super easy! Just remove the spark plug from the engine cylinder head and place the ground tip which is attached to the metal bottom thread base of the spark plug against the side of the engine. This will ground the spark plug to the engine and allow the electric charge to flow when the engine is rolled over. Rolling the engine over occurs when you try to start the engine using the electric starter or kick starter. With the spark plug removed from the cylinder the engine will not start, it will just roll over.
When you roll the engine over you should now see spark between the center electrode and the ground tip on the spark plug. Be careful when you are grounding out the spark plug to the engine. If you are not careful you may end up getting a bit of a zap from the spark plug or high tension wire. The charge is not high enough to seriously injure you, but you will be wide awake afterwards.
If you do not see spark...I would replace the spark plug right away. Spark plugs can fail in a variety of ways. Hard start, intermittent firing, poor performance and no starts can all be the fault of a bad plug. So I advise customers that spending $5.00 on a good spark plug is a great investment. Very often this cures a host of poor engine operation issues.
If in doubt chuck that spark plug out!
Tim...can I use any replacement spark plug when I need a new one for my bike?
Yes!, you can replace your spark plug with a spark plug from any manufacturer. Just take your old plug with you to your local auto store or hardware store. The counter person will be able to cross reference the plug numbers on your spark plug to a variety of replacement plugs.
Ensure that your new spark plug looks the same as your old spark plug, set the spark plug gap and you will be fine.
Personally, I prefer NGK spark plugs as I find they perform better and last longer than most plugs in my experience. The great thing is that they cost only a little more than a stock spark plug and still less than $5.00 each.
I my opinion this is the least expensive, high performance part you can add to your bike.
Tim...what is the “spark plug” gap commonly found on 110 cc and 125 cc gas engines?
Spark plug gap is the distance between in the air gap between the center electrode and the ground tip.
Typically the air gap on a 110 cc or 125 cc engine spark plug is .028 inches which is about the thickness of a bank card.
So if you can fit your bank card into the air gap it is fine. Better yet use a feeler gauge set to .028 inches, this is the most accurate measure. If the air gap is not properly set simply bend the ground tip up or down as needed to achieve the desired air gap.
Proper spark plug air gap ensures that the spark produced by the spark plug is the proper length to ignite the air fuel mixture in the cylinder. This will keep your engine firing at its best!
Tim...I installed a new spark plug and still have no spark, what do I check now?
This is where things get a little more complicated. You checked for spark, had none and then replaced your old spark plug. You try the bike again and still have no spark.
It can be a little frustrating but no need to lose your cool.
You can watch our video on how to test for spark, spark plug performance, and installation by clicking here
Check out our blog next week as we run though the complete ignition system on your bike.
We will examine ways to check and see which component has failed and get you on the road once again.
If you have any tech questions about our bikes, please feel free to email them to...
Have a great day!
Technical Support Specialist
Venom Motor Sports