not enough spark to start

[Alex.bikes]

I am working on a yamaha moto 4 badger, 80cc quad. It has everything it needs to run exept enough spark. I bought a new spark plug and ignition coil and it has spark now. There is not enough spark to actually start the engine yet, even on starter fluid. it is a c7HSA spark plug, and am looking for a plug that will produce more spark. Any ideas on how to get more spark? Anything will help

 

[panchothedog]

Is that the plug recommended by Yamaha? Plugs can be to short, and to long
( that's bad ) and have different heat ranges. But I don't think a different plug is going to produce MORE spark. Run the plug recommended by Yamaha. If you can see the spark when it's grounded outside the engine, that should be enough. You might have other problems.

 

[Alex.bikes]

I am using the one reccomended by yamaha but it isn't enough spark for the engine to actually fire. Any ideas on how else I can fix this?

 

[Whitetrashrocker]

Need more info.
Is the cylinder getting fuel?
Is there compression?
What's the story?

 

[Master Hack]

Tesla coils work well.

 

[Denny]

If it won’t start on starting fluid it may have a compression or timing problem.

 

[Rat]

I am using the one reccomended by yamaha but it isn't enough spark for the engine to actually fire. Any ideas on how else I can fix this?

Not enough spark

An engine will run on weak spark, not great but it will for intents and purposes start and run good enough.

On that note, You do not know that you have good spark just because you have a pretty spark in open air... 100psi of internal pressure changes how things work lot and that's not even "good" compression being that 90psi is the service manual recomendation for replacing the rings in most smaller engines.

You're probably not getting enough or maybe any gas into even ignite so that a carb tear down.

Having gas in the carburetor bowl does not mean it's getting into the engine.

Timing could even be off a few degrees

Bad valve lash holding open a valve

bad cam timing (cam chain jumped a tooth or two) if it's OHC instead of OHV

I could throw a longer list of reasons it won't start... but "NOT ENOUGH SPARK" will never be among them.
Your mechanical ignorance might be though.

 

[Alex.bikes]

I tested the carb on my minibike and it was good. It was a quad that my uncle had outside for a few years. Has compression fuel everything it needs to run, but problems with spark. Sounds like it could possible be timing as well.

 

[Rat]

I tested the carb on my minibike and it was good. It was a quad that my uncle had outside for a few years. Has compression fuel everything it needs to run, but problems with spark. Sounds like it could possible be timing as well.

Well if you put the carb on a running engine and it still ran... that's good

It could still be sucking air through a flattened out sun baked intake gasket.

The only thing I know for 1000% sure is it's not a matter of "Not enough spark" please never say some dumb crap like that again.

The spark could be intermittent,
The spark could be out of time,
There are at least a dozen reasons why an engine that seems like it should run, doesn't.

 

[Denny]

Start with doing a dry and then wet compression test.

 

[Rat]

Bad Valve Timing
Bad Spark Timing
Bad valve lash setting
Dropped Rod (ohv)
Bad Compression
Bad Intake Gasket
A/F screw adjusted wrong for the engine in question
Idle set wrong for the engine in question

Loose spark wire
Loose spark cap

The last two specifically can cause no spark in any given position as well as fire in others... it's a crap shoot.
Remove wire, trim by 1/4" on each end, squirt some dielectric grease where it goes into the boot and coil thread back in tight.

It did occur to me another issue could be if it's a resistor cap (3-5 Ω) there's possibly an issue with the spring in the resistor holder (heat or rust) which could cause intermittent spark issues or no spark at all. For this reason I DO NOT USE RESISTOR CAPS; I remove, and replace them as soon as possible. I also refuse to use resistor plugs (NGK BPR5ES denotes being a resistor plug opposed to NGK BP5ES not having a resistor) simply because a plug is worthless the second the resistor blows... no resistor means a plug that can potentially fire for decades reliably. I've seen 60 year old plugs that still fired of like new simply because they had no resistor and the engine they were in was pampered and serviced regularly.

 

[Master Hack]

Start with doing a dry and then wet compression test

That wet test is tricky! It has to be completly wet. If you can find a neighborhood pool, get in the shallow end with the test subject and proceed as you would with the dry test.
Denny should have tips!

 

[Denny]

Terry, you’re thinking of the wrong wet test. The one you’re thinking of is for the ladies. After you throw them into the pool when the come back up if they want to kill you their bad. If their laughing, their keepers!!!

 

[Denny]

The correct way to do a compression wet test is to add a teaspoon of 10w30 and see if the compression comes up more. If it does better start tearing it apart.

 

[Alex.bikes]

right on brother