1974 Kawasaki F7 Spark Problem - Kawasaki Motorcycle Forums
 
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post #1 of 10 (permalink) Old 09-19-2013, 02:00 AM Thread Starter
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1974 Kawasaki F7 Spark Problem

Hello All!

I purchased a very well maintained 1974 Kawasaki F7 (175cc) about Six Years ago, and it ran great. After about a year, I was teaching one of my children to ride, and I parked the bike using only the Kill Switch to shut it down, leaving the Key in the On Position, althouth the light/s were not turned on. It sat this way for about 4 (+/-) hours, and when I went to fire the bike back up, NOTHING. I usually never park a Dual Purpose Bike this way, but for some reason, this time I did.

I pulled the plug, connected the coil wire, held the plug's base to a good ground, kicked it over several times, and I had NO SPARK. I played around with it for a while, and it still didn't produce a spark. The Kill Switch still felt like it was operating smoothly, but I disconnected it "just in case". Weird!

I have had many other projects going on, and now I want to get this bike running again. I know I'm going to have to clean the entire fuel system, including tearing down and cleaning the carburetor. I thought I would have gotten to this issue before now, or I would have drained everything before I let it sit for Five Years.

I hope to get as many of your suggestions regarding this "No Spark" issue as possible.

I've been riding for quite some time, and have owned quite a few bikes. The way this "No Spark" issue came about seems strange to me. I feel as if I'm overlooking something very simple.

ANY AND ALL SUGGESTIONS WOULD BE VERY MUCH APPRECIATED!

Thank's in advance for your valued feedback.
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post #2 of 10 (permalink) Old 09-19-2013, 09:49 AM
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Re: 1974 Kawasaki F7 Spark Problem

I don't know much about your bike model but if you left the key in the ON position, there is a good chance the battery is dead because the KILL switch only kills power to the ignition coil and not anything that may be wired other than that; many bikes will have the tail light wired separately as a safety feature and you could have had the light remain on when you parked it or something similar. Test the battery with a hydrometer (small ones are available at any auto parts store) and if all cells are in good condition (top with distilled water), charge and then try it. If the battery is totally dead, you won't get spark and if you jump start the bike or kick start, it won't run decently until the battery is charged some.

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post #3 of 10 (permalink) Old 09-19-2013, 10:17 AM
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Re: 1974 Kawasaki F7 Spark Problem

Your in luck I have several videos on my website that will help you get up and running. (links posted below) A "no spark" condition could be as simple as a broken wire grounding out the ignition somewhere along the line either from the kill switch to the coil or the key switch to ground (see wiring diagram on my site). Leaving the key "on" with or without a battery present had nothing to do with the issue as this bike does not require a battery to run. If the problem is not as simple as a grounding issue, there are some tests you can perform on the exciter and signal coils of the ignition that reside behind the flywheel (there is also the lighting and charging coil but those have no impact on the ignition). You can test the high tension coil as well however that is usually not the problem in most cases.

This is part of my "Barn Fresh" motorcycle restoration series of my 1970 F5 (350) Big Horn, it uses the same ignition as your F7. This particular episode deals with carburation and ignition, I to had a "no spark" situation and this video shows how I diagnosed it. The picture at the top of the page shows what the ignition looks like however I go into detail in the video. Episode 7 shows the bike running after I found the problem.
Barn Fresh Episode 6 - Motorcycle How to and Repair

You may want to watch the entire 13 episode series to see the bike restored from start, from finding it and pulling it literally out of a barn, to the final finished bike at it's first show.

Here are two other videos that dive specifically (and more generally) on how to get a non running motorcycle running again
getting a bike running - Motorcycle How to and Repair

This is part 2 following up on the first video
getting a bike running part2 - Motorcycle How to and Repair

ServiceManuals - Motorcycle How to and Repair Here is a link to a page where I have various wiring diagrams and the test values for different ignition components. Your F7 wiring is there as well as info on testing the exciter and signal coils.

Be sure to cruise around my website as I have even more "how to" motocycle/atv videos with lots of tips and information as well as other general motorcycle stuff.

BTW I also have an F7, a first year low frame/engine number 1971 model.

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post #4 of 10 (permalink) Old 09-30-2013, 03:20 PM Thread Starter
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Re: 1974 Kawasaki F7 Spark Problem

Many thanks for your input, "wiredgeorge" and "thejunkman"!

I purchased a reasonably priced ignition coil (the original spark plug wire is getting short anyway, due to cutting it back for a new boot), and selenium rectifier (I inadvertently placed something heavy on my original one, and I didn't trust it after that). I hope this doesn't turn out to be the CDI Unit or one of the Internal Ignition Coils, as I'm certain you're aware they can get a bit expensive.

I'm anxious to pull this bike out and get it running. I thought I would have had the time to do that last week, but I have a business to run, and things come up.

As I mentioned, I'm going to have to do some serious cleaning to the entire fuel system. Seafoam to the rescue there (I hope)! Are there any other little tricks on this that you may know of?

Although I'm experienced at working on bikes, it's amazing how I keep learning new "tips" and "tricks" from other enthusiasts!

Also, what are some of the best parts sources you may know of for these "Vintage" bikes? Obviously some things can be found on Ebay, but any others you may be aware of would be much appreciated. Perhaps maybe even some of you folks have some parts you would be willing to sell?

Once Again, Thank You For Your Replies!

Any Other Replies Would Also Be Welcomed!
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post #5 of 10 (permalink) Old 09-30-2013, 08:42 PM
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Re: 1974 Kawasaki F7 Spark Problem

Well cleaning the fuel system will require you to completely dis-assemble everything and clean it and or replace any suspect rubber parts. Seafoam, while a good product and I use it, is only really for if the engine is running reasonably well and only minor dirt/varnish is suspect. A bike like yours in the condition I think it is in don't even try just dumping it in the tank with some fresh gas and trying to start. It won't start most likely.

I would do some testing to your coils first in diagnosing your ignition problem.

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post #6 of 10 (permalink) Old 08-10-2017, 09:49 AM
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"Leaving the key "on" with or without a battery present had nothing to do with the issue as this bike does not require a battery to run."

junkman,

Regarding your quote above concerning the F7, will running the bike without a battery fry the CDI? i'm finding conflicting information on paper, as well as online. I consider you the master of these machines, so please let me know when you get a chance! I plan on keeping a fresh battery with mine, but i would just like to know the technical implications of battery vs. no battery.

thanks!
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post #7 of 10 (permalink) Old 08-10-2017, 05:34 PM
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CDI has its own independent magneto driven power source, so no harm done if the battery is not present.
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post #8 of 10 (permalink) Old 08-10-2017, 06:42 PM
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Thanks! Is the case the same with the lights? I have an old 6 volt Honda moped that'll run without a battery, but as soon as you hit the lights, they burn out if no battery is present...same case with these older Kawasaki 2 strokes?
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post #9 of 10 (permalink) Old 08-10-2017, 07:55 PM
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Not the same for lights.
All lamps must be present, functioning and of the correct wattage.
Battery must be present and charging system working correctly.
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post #10 of 10 (permalink) Old 07-10-2019, 03:47 PM
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Kawasaki F7 1974 Ignition problems

We have a 74 Kawasaki F7 175 that will not advance spark so it just sits at the 4/6 timing marks when you rev it w a timing light on it (using a 12v battery to power the light). We just replaced a bad cdi w another used cdi to get spark back and it runs like a total dog from midrange up. Anythoughts/ Timing plate hasnt been moved and were trying not to set the base timing off to compensate for the lack of functioning advance.
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