Strange Spark plug problem

jchristy456

XS650 Enthusiast
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Location
Chicago
My fellow 650ers'


I will start with this. I recently took my bike a well know and recommended Chicago mechanic. He helped me tune my carbs and was alot of help. I dropped my bike off and picked it up about a week later. When i picked it up he told me "i couldn't get any spark to test the carbs." He put a 12v battery in line with my ignition. When i got the bike back to my shop i immediately pull out the battery and reconfigure my old setup. It fired up first kick. I currently use and spark cap with a HHB PMA and a pamco pete ignition. So, on to my problem. I rode 10 miles 3 days ago. the bike ran rough but pretty decent. I get back and i pull the plugs and the LEFT plug was decent looking and the RIGHT plug was very black and super fouled. I immediately think carbs. However after talking to a fellow 650 guy he tells me to put two new plugs in and swap my plug wires. I do exactly this. I rode ten more miles and it turns out that the problem followed the plug wire. Now with that being said i think that this has something to do with the guy that worked on my carbs putting a battery in-line and bypassing my sparks CAP. Any help would be super appreciated. I'm still a beginner. Thanks in advance. :banghead:
 
jchristy456,

Measure the resistance from one spark plug cap to the other. Should be 20K to 25K with 5K resistor caps. If the cap on the bad wire is open, that could cause a weak spark to that cylinder.
 
Ok so i measured the resistance and it was 23.1K. that seems to be in order. I'm putting new plugs in it again tonight and switching the plug wires one more time and running one mre test to ensure that the problem follows the plug. any other suggestions?
 
Took her out adjusted the fuel mix screws every 300 ft of riding and got it close. Full throttle no problem once I gets goin, quite a low end flat spot getting through the initial excellent. Hmm
 
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