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KE 100 Spark plug Fouling

Discussion in 'Bike Mods, Performance, Maintenance & Repair' started by jcduncan, Jan 10, 2005.

  1. jcduncan

    jcduncan Rookie DRN Member

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    1976 KE 100 starter bike for my son. He just wants to ride it in open fields until he feels comfortable on trails not BMX racing. The engine runs for about 10 minutes & then fouls the plug. Can anyone assist me with this problem?


  2. Phydeaux

    Phydeaux Rookie DRN Member

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    I had an old Kaw G5 100 (similar to your KE100) that started fouling plugs all of a sudden. After a couple of evenings of tinkering I found that the oil injector pump was stuck wide open. Once that was remedied it quit fouling plugs.

    Also, are you certain that the plugs you are using are the proper heat range? A cold plug running at low speeds may foul pretty quickly.

    Another thing to check is the choke/enrichener circuit in the carburetor. If it is not closing completely the rich mixture could be causing your problems.

    There are probably other possible causes, but these three should get you started on troubleshooting your problem. Good luck.
  3. jcduncan

    jcduncan Rookie DRN Member

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    Can you explain what the choke/enrichener circuit is?

    The plug idea will definitely be tried tomorrow. Thanks!

    Last, How can I determine if the oil injector pump is stuck open & can I fix it or will I have to replace the oil injector pump? Your advice is truly appreciated.
  4. reelrazor

    reelrazor Rookie DRN Member

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    Choke/enrichener is a plunger that adds more fuel for start-up. The lever on the carb that says 'choke' is directly attached to it. Basically make sure that the plunger that it operates is disappearing into the carb body. It(the plunger shaft) should have some wear on it(it will be brass) and it will slide thru a rubber collar. All of the bright brass should be hidden in the 'off' position.

    Follow the throttle cable back from the carb. You will find that it makes a fork with another cable that leads to the oil pump. There will be a cover over the oil pump(either in the side case of the engine, or behind the front sprocket-I can't remember which on those bikes). The pump cable will attach to a lever or a wheel on the pump that will either move as you operate the throttle or it won't.

    There are usually marks on the lever/wheel which are supposed to line up with a mark on the mount/pump.

    If it has been sitting a while you may need to wring it out for him and clear the crankcases of old oil. get it warm and let er scream a few gears.
  5. Phydeaux

    Phydeaux Rookie DRN Member

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    Wellllll, . . . it's like this, it's been probably 20 years since I owned that old Kaw, so my memory might be a bit fuzzy, but here goes.

    Your little Kaw has a rotary valve engine, so the carb is mounted on the right hand side of the engine under the cover at the front of the engine. To check the oil injector pump or the carburetor you will need to remove that cover.

    For cold starting there is an enrichener circuit (not an electrical circuit but a path for fuel flow) built into the carb. When you pull out on the "choke" knob it moves a plunger up and allows additional fuel into the engine. Once the engine is warmed up a little bit the knob should be pushed all the way back in to prevent the engine from running rich when warm and fouling a plug. If the plunger doesn't fully seat and block fuel flow it will continue to feed too much fuel to the engine. There is usually a little plastic threaded fitting that the choke cable runs through to the plunger. The first thing you can check is to determine if there is a little bit of slack in the cable when the choke is pushed in. If there is then it's likely you don't have any problem there. You can unscrew the fitting and pull out the plunger, spring , and fitting. Don't take the assembly apart unless you need to replace parts. The only reason to pull this assembly out is if you think that the plunger is binding up in the carb.

    The carb and oil pump are both operated by the throttle cable. The throttle cable splits and goes two directions as it enters the area under the cover. One end goes to the carb and the other goes to the oil pump. When you twist the throttle the cable running to the oil pump should rotate a little arm on the pump. As long as it moves back and forth and is returning all the way to a stop or to the end of the cable travel it's probably ok. There are some adjustments to the travel that can be made, but usually this only needs to be done when the throttle cable is replaced, and as long as it's close you should be fine.

    One more thing occured to me. What type of oil are you running in your injector tank under the seat? It should be two stroke injector oil. If the tank is full of four stroke oil or two stroke pre-mix oil it will also foul plugs. I used to run Bel-Ray Si-7 injector oil and had no problems. If you aren't sure what type of oil is in the tank or if you know it's the wrong stuff drain the tank and put the right stuff in there. Be sure to get an oil for "autolube" or "injector" systems. Any decent dealer should be able to give you the right stuff. The bike will have to flush out the oil in the lines while the engine is running, so you might foul another plug or two, but then it should be fine. This could be the source of all of your problems.

    It's hard to diagnose things long distance, and if you aren't too mechanically inclined you could be getting in over your head, but most of what you are looking at isn't too complicated. Just be patient and don't break things. Oh, you also might need an impact tool to knock the screws loose in the cover over the carb. I hope I haven't told you too much. ;^)

    I'll check back if you have additional questions.
    Last edited: Jan 10, 2005
  6. Okiewan

    Okiewan DRN is my fault.

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    Umm.. disconnect the oil injector and just run pre-mix?
  7. yamahonky

    yamahonky Rookie DRN Member

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    If you drive slow for a while, it might load up on gas and foul. Just pull the clutch and give it a rev or two to clear it out every once in a while. If your plug is dry and black, coated with carbon, your running too rich. If it is wet with oil, than that's your pump stuck open or the kind of oil in the tank. If all else fails, get a manual for your bike so you can get it jetted just right. :cool:
  8. tbrooks

    tbrooks Rookie DRN Member

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    Hmmmmmmm

    How long has it been since the top end on this bike was serviced? check your compression and buy a repair manuel it will do more for you. most of these bikes were kids bikes ie they ride the hell out of them for hours on end and they don't get worked on unless the will not run. :cool:
  9. pyrofreak

    pyrofreak Rookie DRN Member

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    Anybody know the head bolt torque on the KE100?
  10. Someone

    Someone Rookie DRN Member

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    I was thinking the same thing. My first 2 stroke was a Batavis moped (whopping 49cc's) and after talking to some of my more fortunate friends with YZ 80's, they convinced me to do the same. They also wanted to rip my engine apart to give me more power, but my dad would have killed me (he rode it too and thought it was too fast at 35mph downhill). :)
  11. Phydeaux

    Phydeaux Rookie DRN Member

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    Head bolt torque - 2.2kg-m or about 16 ft-lb (or lb-ft if you prefer)
  12. pyrofreak

    pyrofreak Rookie DRN Member

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    Phydeaux- Thank You So Much!!!!!!!!!!!!!!!!!!!!!!!!!!!!
  13. jcskibby

    jcskibby Rookie DRN Member

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    i like the pre mix idea,could anyone tell me the proper pre mix ratio?
  14. Phydeaux

    Phydeaux Rookie DRN Member

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    The ratio depends somewhat on the oil you use and a lot on strong opinions and folklore. In my 2-stroke days I always ran Bel-ray at 32:1. I never had any trouble with fouling plugs and I never burned up an engine. The wrist pin bearing and dry side crank bearings lasted about forever. Oil has changed a lot in the last 15 years tho', so maybe there are others who can offer recommendations based on more current experience with modern lubes.
  15. 91-YZ250-Chris

    91-YZ250-Chris Rookie DRN Member

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    Please take out the oil pump, I fried my ke100 motor because the darn thing failed. Just take out the gear behind the oil pump and put it all back together. This will also help with the fouling plugs at low speeds. Oil injection is awsome till it breaks and your stuck with having to buy a new top end.
  16. reelrazor

    reelrazor Rookie DRN Member

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    In 20 plus years of working on bikes and snowmobles for a living I have seen 0(that's ZERO-NONE) oil pumps 'fail'. I have seen lines come off, and pump drive belts(sleds) break. I have seen drive gears strip(always heavy clutch and tranny wear along with that-tells you something about the maintenence habits-some people think that since they are putting oil in the tank and it disappears that they never have to change oil). I have seen people allow enough dirt into the tank that it blocked flow of feed oil to the pump. I have seen lots of air in the lines indicating the tank was allowed to go empty at least once. I have seen throttle/pump cables be un-maintained to the point that the cable breaks that actuates the pump.

    I cannot count(too many) seizures I have repaired because people mistakenly put straight(unmixed) gas in their gas tank.
  17. Phydeaux

    Phydeaux Rookie DRN Member

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    I have to agree with reelrazor on this one. I've seen pump cables break, and plastic hoses crack or pull loose, tanks clogged with gook, and even loose mounting screws but never an out right pump failure. Sure, if you're going racing ditch the pump but if you're just going to bop around in a field and have fun the autolube set up is pretty bullet-proof. And when was the last time you saw a KE100 on the starting grid?
  18. jcskibby

    jcskibby Rookie DRN Member

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    you just should of seen me smoke this old guy in his electric
    scooter at the grocery store parking lot! :laugh:
    thank you all for helping me,this bike was a gift,it starts on the first kick,but i have to repair,service,and clean what looks like many years of neglect,thanks'again!!
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