94 KE100 needs a fresh spark plug every start.

  • ckahleer
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94 KE100 needs a fresh spark plug every start.

21 Jul 2025 19:23 - 21 Jul 2025 19:27
#914921
 I went for a honey-do list ride today. First stop. Home Depot. in store for 20 minuites. Got back on the bike and it would not start. Put in fresh spark plug and it started first kick. Next stop the grocery store. Same thing, bike would not start when done shopping. Replaced spark plug, and it started first kick. This is nothing new, I carry 8 spark plugs with me. I had the carb off and cleaned twice Jet sizes, float height, air screw setting all comply  to service manual. see pic of plug. Looks rich to me, bur not sure how a 2 stroke plug should look.

 


 
1997 ZL600
94 KE100
82 KZ305
74 TC185
Last edit: 21 Jul 2025 19:27 by ckahleer.

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  • Wookie58
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Re: 94 KE100 needs a fresh spark plug every start.

22 Jul 2025 01:09
#914935
The colour doesn't look too bad, is it "over oiling" ? (2 stroke pump setting)
1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca

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Re: 94 KE100 needs a fresh spark plug every start.

23 Jul 2025 03:10
#914979
Have you ever performed a "lower-end" leak-down test? I do quite a few two-stroke stuff and subsequently why i have drawers of "custom" made block-off plates for the test. Plug, like Wookie states, doesn't look too bad..but..could have an iffy Rotor side crankshaft seal. Yours is of the rotary style intake induction and the Bakelite style sealing sleeve. You can get air leaks between carb and rotary valve cover resulting in having to "over choke" it to get it going. Also of course, eventhough it might seem like it has decent compression, does it really? Might have stuck/worn rings/cylinder/piston clearance issues. I always bore/oversize everytime i work on these little engines, just good refresh and insurance against possible problems. 
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Re: 94 KE100 needs a fresh spark plug every start.

23 Jul 2025 07:09
#914983
asphalt900 wrote:
Have you ever performed a "lower-end" leak-down test? I do quite a few two-stroke stuff and subsequently why i have drawers of "custom" made block-off plates for the test. Plug, like Wookie states, doesn't look too bad..but..could have an iffy Rotor side crankshaft seal. Yours is of the rotary style intake induction and the Bakelite style sealing sleeve. You can get air leaks between carb and rotary valve cover resulting in having to "over choke" it to get it going. Also of course, eventhough it might seem like it has decent compression, does it really? Might have stuck/worn rings/cylinder/piston clearance issues. I always bore/oversize everytime i work on these little engines, just good refresh and insurance against possible problems. 
Some of this is a little above my pay grade. I'm more of a shade tree mechanic, But will look into your suggestions once I get back from Mid Ohio Vintage Motorcycle Days.

Wookie, I tested oil consumption. The service manual specs are 2.6 - 3.0ml in 3 minutes at 2K rpm, with oil pump held full open. My test resulted in 4.0ml. Do you think this is enough to cause my problem?
I may have been a little high on the RPMs though. I need to get a get a better test tachometer and recheck.

Anyone at mid Ohio who sees a guy with a green KE100, along side the road, replacing his spark plug, that will be me.Stop and say Hi. Bike is loaded in the van and I'm ready to go!
1997 ZL600
94 KE100
82 KZ305
74 TC185

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Re: 94 KE100 needs a fresh spark plug every start.

23 Jul 2025 07:47
#914985
ckahleer wrote:
Anyone at mid Ohio who sees a guy with a green KE100, along side the road, replacing his spark plug, that will be me.Stop and say Hi. Bike is loaded in the van and I'm ready to go!
 
Will do! 
[img
1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1980 KZ440B
1981 Yamaha XT250H
1981 KZ440 LTD project bike
1981 GPz550
2013 Yamaha FZ6R

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Re: 94 KE100 needs a fresh spark plug every start.

23 Jul 2025 08:38
#914986
So... dumb question: is it possible that there is a poor connection in the coil / wire / plug cap that fails after sitting with a hot engine, giving you no spark, and then the act of removing / replacing the cap pushes the poor connection back together? 

Also when it doesn't start, do you check for spark before replacing the plug? I didn't see that in your description. 
1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1980 KZ440B
1981 Yamaha XT250H
1981 KZ440 LTD project bike
1981 GPz550
2013 Yamaha FZ6R

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Re: 94 KE100 needs a fresh spark plug every start.

23 Jul 2025 09:42
#914989
Before You find Yourself stranded and Nerdy has to loft your little bike to a safe depot, check some stuff ya might of missed. That tiny bypass hole circled in marker, has to be clear, essential!!  Should be able to shine a light thru the pilot jet hole and clearly see a ROUND hole. Gotta emphasize Magnifying glass!! Without it all you will see is a glimmer of light, Really focus the glass on it!! I have containers of this stuff, isn't above Your pay-grade, just look better. You cats have fun up there!!!     

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Re: 94 KE100 needs a fresh spark plug every start.

23 Jul 2025 11:05
#914994
ckahleer wrote:
 
Wookie, I tested oil consumption. The service manual specs are 2.6 - 3.0ml in 3 minutes at 2K rpm, with oil pump held full open. My test resulted in 4.0ml. Do you think this is enough to cause my problem?
I may have been a little high on the RPMs though. I need to get a get a better test tachometer and recheck.

Anyone at mid Ohio who sees a guy with a green KE100, along side the road, replacing his spark plug, that will be me.Stop and say Hi. Bike is loaded in the van and I'm ready to go!
Unlikely to be honest, too much oil effects the combustibility of the fuel but being a little over will help reduce the risk of seizures (I assume you thrash it with no mercy)
1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca

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Re: 94 KE100 needs a fresh spark plug every start.

23 Jul 2025 11:34
#914998
Wookie58 wrote:
 (I assume you thrash it with no mercy)
Is there another way to ride a 100cc 2-stroke?
1997 ZL600
94 KE100
82 KZ305
74 TC185

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Re: 94 KE100 needs a fresh spark plug every start.

23 Jul 2025 11:52
#915000
ckahleer wrote:
Wookie58 wrote:
 (I assume you thrash it with no mercy)
Is there another way to ride a 100cc 2-stroke?
[img
[img
[img
1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca

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Re: 94 KE100 needs a fresh spark plug every start.

23 Jul 2025 12:23 - 23 Jul 2025 12:37
#915001
Drain the autolube dry and run it on  premix to see if the plug still fouls with a reasonable mix ratio of 30:1?
Is the plug heat range correct? 
Does both the plug and cap have resistors in causing a weak spark? 
Don't do oil burners myself but just suggesting stuff. 
🤷
[img
[img
[img
[img
[img

Z1000J2 somewhat modified!
[img

Last edit: 23 Jul 2025 12:37 by Warren3200gt.

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Re: 94 KE100 needs a fresh spark plug every start.

23 Jul 2025 13:07 - 23 Jul 2025 13:08
#915004
Nerdy wrote:
So... dumb question: is it possible that there is a poor connection in the coil / wire / plug cap that fails after sitting with a hot engine, giving you no spark, and then the act of removing / replacing the cap pushes the poor connection back together? 

Also when it doesn't start, do you check for spark before replacing the plug? I didn't see that in your description. 
I replaced the ignition coil with the one in the attached pic.(the origional one would fail when it got wet). checked wiring from points to ignition coil , resistance of coils behind rotor, cleaned and set points for correct ignition timing. There is no spark when the bike will not start, but I can still shock myself real good. All it takes to get the plug working again, is spraying carb cleaner in it and drying it out. I'd go broke always putting in new plugs, so I have been cleaning and rotating the same plugs. 
1997 ZL600
94 KE100
82 KZ305
74 TC185
Last edit: 23 Jul 2025 13:08 by ckahleer.
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