I'm working on an 04.5 sp500 with a bogging issue, went through all the fuel system and no am onto the electrical, the manual says to check the resistance between the spark plug wire and the left lead of the coil which is supposed to be 10.5ohms. I can't get any reading from either of the two leads on the coil. Plus it says to check the coil mount for a good ground to the engine. The coil is insulated with a plastic shell of course so am I just checking the bolt that mounts the coil to the mounting tab to the engine? Also it talks about checking the secondary coil, where is this, I only see one coil. Is there a way to check the resistance of the spark plug wire another way and can you replace the plug wire without replacing the coil?

 

I think I figured out to test the coil but need to know what my readings mean by those more knowledgeable about electricity. First off I couldn't get an ohm reading between the coil and the end of the spark plug wire so I unscrewed the resistor cap and cut off the end of the wire a bit, screwed the cap back on and had good contact. The book says the ohm readings should be 10,500k from the coil to end of plug wire, my reading was 25,000k, I guess telling my I have more resistance than what is called for, does this mean that I will have a weaker spark because of more resistance?

 

i would take a reading with the boot off and see what you come with.
i would also try to see if you have spark now since your actually getting a reading.

 

I get a reading of about 20,000K ohm with the boot off, which is about 5k less so I guess the resistor park of the plug wire is working. Also when I checked the cdi box for output the manual says it shoud be about 300v but my reading was almost 500v. Why all my readings are high I don't know. I always had spark so it's hard to tell if it's more than before regardless my problem still exsists. I have a buddy with the same machine as mine so I'm going to test his and see what his readings are then I'll have something to compare it to.

 

I checked the coil on my buddy's machine and his coil reads 12.3K ohm (book says about 10K)from the primary lead to the end of the plug wire vs 25K on mine, so it looks like I may have a bad coil. The output on his cdi box was the same as mine, about 500v. Now to shell out $146 for a new coil, ouch!

 

Try another DVM could be the one you have is reading wrong. Bogging issue? Color of the plugs? Lean rich? Does it backfire? If the plugs show they are burning correct then move on to the fuel side of it. We Need more info!

 

My machine started acting up when I was plowing the other day, it was like someone flipped a switch and all of a sudden it started cutting out and missing badly. It would idle fine but when you go to give it gas it will start missing. The plug is sooty. I went through the entire fuel system and didn't find anything wrong that's when I went to the electrical. Based on what I found with the coil that's my next move, I 've got a new one coming that I bought off ebay for a fraction of the cost they want from the dealer. If it's not the coil I don't know where to go from here.

 

usually if its something with your coil it's gonna make it so the machine doesn't run at all. If your plug is black then it is most likely rich, put a new plug in it and see if that helps if it does then you need to adjust your carburetor so your not fouling your plug

 

I've tried new plugs and they soot up when the machine starts missing. Like I've said I've gone through the fuel system, completely disassembled the carb and found nothing out of specs. Like I said my problem came on like a flip of the switch so I'm hoping the coil does it, plus being my ohm readings were off from what the specs are I'm thinking that may be it.

 

Can you check volts at the battery 12-6 12-9 static then 13-6 14-7 running is what you need? Did you check volts at the coil then back to the ignition switch ?