Spark Plug Problem

Discussion in 'General Questions' started by GnomeGuy, Jun 7, 2014.

  1. GnomeGuy

    GnomeGuy New Member

    Im having spark plug clearance problems, with park plug and cap on, im just about 2-3/16th too tall, which resulted in a busted cap and bent spark plug. I will be replacing them, and im wondering if they make really short spark plugs for motorized bikes? Also do you think i could sort of lean the motor a little to the left or right to give clearance to a normal size spark plug without effecting the chain to the sprocket. Ive included two pictures of what im working with. The bike ran awesome until the spark plug cover and plug broke. :grin5:
    2014-06-06 23.37.32.jpg Photo Jun 06, 11 37 25 PM.jpg
     

  2. butre

    butre Well-Known Member

    Try a Champion CJ7Y or equivalent. They're about $2.40

    If that's not short enough you'll have to switch to an angle fire head.
     
  3. GnomeGuy

    GnomeGuy New Member



    Ok ill look that up, how can i find the CC's of my bike, i recieved my bike for free from an friend who moved away, and his dad built it for him, so he didnt know the CC's, but i seem to get about 25-35 mph out of it.
     
    Last edited: Jun 7, 2014
  4. butre

    butre Well-Known Member

    You can take off the cylinder head and measure the bore diameter and stroke. If he's getting 35 out of it it's probably a 66cc.
     
  5. KCvale

    KCvale Motorized Bicycle Vendor

    I agree, most likely a 66cc so this slant head for $10 may work.
    http://www.gasbike.net/bike-motor-parts-cylinder-head-cover-super-rat-gt5a.html

    When it comes to plugs I replace the stock plug with an NGK 5944 (BPR7HIX) Iridium, you will actually feel the difference in power.
     
  6. crassius

    crassius Well-Known Member

    I've seen slant heads for both 50cc & 66cc, but not sure they are still made. Wish there was a pic of bike to see if motor mount could be adjusted for more clearance as leaning the motor to the side is a bad way to go.
     
  7. GnomeGuy

    GnomeGuy New Member

    Ask and you shall recieve :) I am using an extra wide motor mount for the bike tube(cut vibration to almost nothing)
    photo 1.jpg photo 2.jpg photo 3.jpg
     
  8. crassius

    crassius Well-Known Member

    non-standard mounting method - looks to be trying to save the front derailer by mounting the motor with the front mount too high

    easiest thing to do is toss the front derailer (hardly used anyway & chain could be lifted with a finger if needed) - this would allow the motor to sit lower & have the carb at a level angle too

    a bit more work would be to lift the rear even more & drop the front by removing that flat plate & inserting enough PVC in front to fill the gap (possibly need longer studs) - this might still allow use of front derailer)
     
  9. Big Red

    Big Red Active Member

    crassius, As usual, is right. get rid of the front derailer so the front mount can move down. I do this every time before I even TRY to mount the engine. You dont need all those gears anyway, It's not a peddle bike anymore, Is it!!!
    Big Red.
    Yeah, I've been gone a while, I'm trying to get back, just taking some time getting there. This getting old CRAP aint for sissies. Did anyone even miss me? Probably not.
     
  10. GnomeGuy

    GnomeGuy New Member


    Im going to do that, i never thought of taking off the front derailer on the sprocket. Im not a very tall guy, which is why i really want this smaller bike to work.
     
  11. GnomeGuy

    GnomeGuy New Member

    One last thing, if i get a Champion CJ7Y Spark plug, can i still use standard Spark Plug Cap? OR do i have to get a special cap?
     
  12. butre

    butre Well-Known Member

    You can use the same cap, but you might have to trim the rubber part down a little bit.
     
  13. GnomeGuy

    GnomeGuy New Member

    Ok, good to know, thank you everyone for your tips, advice, and information! I look forward to getting my little commuter working again, putting gas in my car is getting way to expensive.
     
  14. KCvale

    KCvale Motorized Bicycle Vendor

    I concur as well, the carb is actually tilting back.
    I also remove the front derailleur on every build but not just for engine mounting, it's to get the blasted control off the handlebars!

    With a 2-stroke you are adding a clutch lever and a twist throttle to the handlebars that already has 2 levers and 2 twist or thumb shifters.

    Two things have to go to make it safe and easy to operate for my builds.
    A brake lever and the front derailleur.

    If the bike has a 'half grip' rotary shifters piece of cake!

    Remove the front derailleur shifter and move the right (rear wheel) shifter to the left which will be upside down but work, and replace both brake levers with a $10 SBP dual pull brake lever on the right.

    [​IMG]

    If your bike has combo brake-shifter levers screw em, your local bike shop if it's anything like mine will gladly hand you a brand new rotary rear gear shifter in exchange for a full set of front and rear matched combo brake shifters with the front derailleur and it's cable.

    Remember it's seldom just you that ever rides your machine to boot, simple controls are better for everyone.
     
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