Ordered a new coil today. Figured I should mate it to a new plug cap as well. The factory cap is INSANE expensive, and does not even come with the rubber boots for either end. I looked at the factory cap and it reads "NICHIWA XD05F". So after some looking, I come across a ton of listings for an NGK cap that is printed with "XD05F". It is a universal 102 degree cap that comes with the boots on it. It is also dirt cheap. Now I have never heard of Nichiwa, but I have a lot of experience with NGK. I found it very strange that there is really no mention of the use of these on the forums or on youtube. It is a resistor cap, but can be used on non resistor plugs according to the ebay listing I bought it from. Only $7 shipped, so if you guys say it's a terrible idea, it will be no big deal. Here is the description copied from the NGK site. I read on the Dennis Kirk site that if a bike starts and runs fine, but then dies when it warms up, that it could be an electrical issue. I have been chasing an issue with this bike for several days. Tonight, I installed a new plug which made it run better, and longer before it died, but died nonetheless. Then I decided since I was ordering a new coil, I would cut the pug wire back a bit and thread the cap into it and see if it helped. It did not. It made it worse, but seemingly the same symptoms, just worse. Thoughts on using this cap, and wtf I got going on with this thing? There is not much mention of coils, nor plug caps on here. I am really hoping I do not have a bad CDI/ECU. My apologies for all the new threads. I do use the search function prior to posting. Mods, please feel free to delete the "Could it be the COIL?" thread. No one answered it. Perhaps from lack of interest, or lack of experience. Again, below is the description from the NGK site for the plug cap. One can easily find photos of it by searching NGK XD05F. I am very anxious to hear some feedback on this.

Resistor covers may be required for power sport applications when spark plugs alone don't provide sufficient noise suppression. Designed to reduce electro magnetic interference and radio frequency interference, which can interfere with electronic ignition components, causing misfires and poor engine performance.

• Highly durable phenolic resin and EPDM rubber
• Ceramic resistors ensure optimum performance and reliability
• Built to withstand extreme heat and vibration
• Prevents flashover
• Ensures optimal service life and performance

https://www.ebay.com/itm/NGK-Spark-P...72.m2749.l2649

https://www.ngk.com/product.aspx?zpid=20072

 

Hmmm, hopefully the new coil will resolve your issue. Air leaks? Have you checked float bowl level? You can check float bowl level by attaching a clear plastic hose to the float bowl drain and bending hose in a U that comes up above float bowl. Gasoline will settle in clear tube at same height as the gas in the float bowl.

 

I've been following your various threads. And I feel your pain, man. Troubleshooting an intermittent issue on what is supposed to be a pleasure vehicle ranks near the top of my list of pet peeves.

I would suggest you update your signature to include where you live. Weather and elevation could be a contributing factor here. Would be different in Yuma AZ vs, say, Boulder CO.

How many miles are on the bike?

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I didnt read all your threads, but did you clean the efi and ignition box connectors already? With alcohol or even wd40 or some deoxidizer product for connectors

 

Just for a test pull the headlight bulb, start the bike, and see if the bike still dies the same. Without the extra load of the headlight a bad coil may be good enough to keep running. I once had a vehicle with a minor crack in one of it's two coils. When I drove during the day it ran fine. At night I turned on the headlights and the engine would almost die. It took a day of digging to figure out it was the coil and not a short somewhere.

Also, you should be able to check resistance through the could against spec, but that won't help if it's a heat induced issue that fails once it warms internally.

 

Yeah, a heat induced electrical component failure or breakdown is a pain. When I worked at a shop, we had a coil machine with an adjustable set of electrode pins behind a sealed glass. You'd hook up a fully charged battery and connect the coil leads to the machine.

You'd turn a dial that increased distance between the pins until the marked/indicated distance could not be overcome by the spark strength. You either had to have a distance value from the manufacturer for such a test or you had to have a known, working coil to compare when the spark broke down.

Even though this wasn't fully heat related, it usually indicated if you had a weak coil and that weakness usually always indicated that it would be worse as heat was applied. Resistance value measurements alone would often not tell you if the coil was weak, but would tell you when the coil was totally dead.