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Old January 29th, 2024, 02:12 PM   #1
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Name: Cody
Location: Oklahoma City
Join Date: Jan 2023

Motorcycle(s): 2007 Ninia 250R

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Ignition Coils and rev hang (?)

Hey all! I've got a 2007 250R, and it's got a fair share of problems. The main two are issues with the ignition coils, and that sometimes when I pull the clutch in, it seems to rev itself up to ~3,000 RPM.

First, ignition coils. I have a misfire on either cylinder between 45-55 mph in top gear, and I don't want to have to spend OE prices ($117/piece) on coils, if there's a cheaper option you all recommend. I tested them and they're showing about 19,000 ohms resistance on the secondary, when spec is 10-k13k. Any recommendations?

Second, the rev hang. It had been laid over at least once when I got it, and it didn't have any hang issues BEFORE it was laid over (I bought it from a friend), and since then, she had the carbs rebuilt, throttle cables replaced, etc. It's been tuned at least twice since the rebuild, and it runs okay otherwise, with good throttle response and power. It doesn't happen all the time, but it's almost a majority. It seems to stick at 3,000, then drop down to idle after a couple seconds, like the throttle is sticking open. I've looked at the throttle connections and it's not hanging open.

Any help is appreciated! TIA!
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Old January 29th, 2024, 03:51 PM   #2
Triple Jim
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Location: North Carolina
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Welcome, Cody!

I doubt if both coils went bad at the same time, and if they're measuring the same resistance, I suspect something is odd about the measurement method. Have you inspected the spark plugs? Misfiring could also be due to carb trouble.

Have the valves been adjusted recently enough that you have reason to think they're in spec? My 2005 was finicky to start and had rev hanging problems like you describe, and a valve adjustment cured those problems.

Hearing that the carbs were rebuilt doesn't instill confidence either, since many rebuilders are less than expert. If a rebuild kit was used, that could be part of all of the problem. Kits contain wrong parts, and if the needles are not genuine Keihin, you could have a lean spot right at 50 mph steady throttle, as an example.
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Old January 29th, 2024, 05:01 PM   #3
"Professional" mechanic
Name: Cody
Location: Oklahoma City
Join Date: Jan 2023

Motorcycle(s): 2007 Ninia 250R

Posts: 2
I did check the resistance following the Kawasaki service manual on both coils, and one said 17,000, the other said 19,000, so I *think* they're just old and about gone. I don't have any records on the bike other than what my friend had done, so I can't be entirely sure.

Both plugs are nearly brand new, less than 1,500 miles on them, and I'm unsure about valve adjustment. It was a decently hard hit from what she told me, so maybe something got knocked loose? I'm not entirely sure.

As for the carb, she shipped it to someone from these here forums and had them rebuild it, not sure exactly who did it though.
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Old January 29th, 2024, 06:31 PM   #4
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Name: Drew
Location: SoCal
Join Date: Jul 2013

Motorcycle(s): 2007 SV650S 2005 EX250F

Posts: 486
Welcome Cody. It sure sounds like gummed up carbs to me. I've had multiple sets rebuilt by one of the locals here on the forum, and he does good work. The problem with these particular carbs is that they are highly susceptible to fuel gumming and even a week or two of old gas sitting can necessitate a tear down and blow through with cleaner.
Don't think, look!
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