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No Spark / Weak Spark

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313 views 3 replies 3 participants last post by  RhinosRKool123  
A
#1 ·
So the '07 Rhino 660 got a new one-way starter clutch bearing. During reassembly, the spark plug boot cracked and broke. I ran the Rhino for testing purposed by just jamming the spark plug wire against the plug. Ran great that one time.

Now it doesn't start. Spark is VERY intermittent and seems weak when I do get it. Battery is charged and on a boost pack. Even just holding the plug wire near the engine, I get spark that seems weak and inconsistent. It ran perfect one time, so I know the timing is good.

I ran through Section 9 of the manual. Every single Step. This is where I'm at:

- New boot has a 5k resistor in it. Manual says 10k resistance is normal. Should still work, right?

- New coil, same result.

- New plug, same result.

- The only thing I can't accurately test is the "Rotator Rotation Direction Detection" coil. My resistance is at .7 ohms, and manual calls for .07-ish ohms, but resistance across my bare multimeter leads is about .6 to .7 ohms, so I think I'm just reading the resistance of the leads themselves. I can't get the resolution to read that low, but its not showing open.

I'm stumped. Its just not getting good spark. The CDI wouldn't affect the spark intensity, would it? I'd think it only effects spark timing.

What could cause the spark to be so weak with a new coil and a full battery on a booster?

Could the stator rotation direction detection coil cause this? I did do some work in the stator cover, but it started and ran beautifully one time after the work was done. I can't imaging the stator decided to die after one use? Maybe?

Did I damage anything by jamming the plug wire against the plug without a boot/resistor?

I'm probably not using OEM plugs, but it ran for years on the old plug just fine until now.

Thanks for any advice,

Mike
 
A
#2 ·
Nope. It was the CDI. Replaced it with a cheap one from Amazon, and it fired right up with a bright blue spark.

Now, in 2025, does anybody still make a good CDI module for this Rhino for under $100? I bought a cheap one for $25 just to get running, but I'd like a real one to run full time.

Thanks!

Mike
 
R
#4 ·
Unfortunately, I saw your post too late to be of help, but to answer one of your questions (that you already figured out), yes the CDI can determine the strength of the spark. CDI stands for Capacitive Discharge Ignition. Basically the capacitor in a CDI takes the electrical energy from the stator and stores it up until the engine needs a spark, then that stored energy gets discharged all at once in a quick, high intensity burst, which then goes to the coil and finally to the spark plug. I had a dirt bike a long time ago and I was stumped because I had pulled the spark plug and I could see that it was getting a spark, but it wouldn’t run. So I just grabbed the plug with my hand and grounded it on the engine when I kicked it over and it didn’t feel like a very strong shock at all. Anyone who has ever been shocked by touching a spark plug knows what a good-working ignition system should feel like (hint: a tazer lol), so I replaced the cdi box and I had a strong spark again.
 
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