"ran when parked"

[G_YamTech_314]

As I posted earlier, I did some work for a friends TW200. I patched it up, and took it for a ride, and he rode it some as well, when we put it away all was well, we said our goodbyes and I put the bike on the battery minder to recharge. I saw the light was green, so I pulled it off, and tested the cranking power of the battery. It was at this point I realized the bike wasn't starting??? Oh. Wtf... So... The plug has 0 ohms resistance, but a plug from my XS has about 5.6k ohms. (Known good plug)

I should mention, I started the bike without choke, and it ran at like 500rpms lol, so I choked it and got it up to speed, he told me to take it for a ride with the choke on, so I did, now I fear the plug may be fouled. Can anyone think of any possible cause? Other than choked ride for 30 seconds? I should add that he rides through deep water, dirt, mud, and dust. Do any of these factors affect the lifespan of a sparkplug with 1100 miles on it?

I just wanna resolve this without telling him so I can avoid the headache if at all possible lol!!

 

[59Tebo]

I wouldn't think your friend's riding locales would have as much to do with the spark plug's lifespan, as much as how he rides it (rpms), carb tuning, etc...
Usually, "ran when parked" is what the PO does!

 

[gggGary]

TW200 stock plug DR8EA
XS650 Stock plug BP7ES
One of those plugs has an R in the part #
R for resistor; the XS650 uses a resistor plug cap instead of a resistor plug. My understanding is the resistance helps the voltage build up before the spark jumps, leading to a bigger fatter spark.
So the TW plug should read 5K from tip to center electrode,the XS650 plug zero (ish) Only one, the plug OR the plug cap should be resistor style.

 

[G_YamTech_314]

So... A new spark plug did NOTHING.

Which means it's gotta be something in the ignition circuit. Probably a coil?

I know that colder weather can sometimes cause coil failure .. but it ran lastnight. I'm so frustrated...