Spark plug gap

Discussion in 'Bicycle Repair' started by Frankfort MB's, Apr 30, 2016.

  1. Frankfort MB's

    Frankfort MB's Well-Known Member

    What is the right gap for a ngk plug on a 66/80cc I run mine at 32 and I'm curious to know what everyone else runs
     

  2. skyash

    skyash Active Member

    I have had so much trouble with this my bikes like big gaps 1mm and bigger some are different and like small gap. I would try every thing you hear about this subject you never no whats best for your bike. it makes a difference.
     
  3. skyash

    skyash Active Member

    After all the tests I whent back to the stock carby and hade better luck
     

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  4. Frankfort MB's

    Frankfort MB's Well-Known Member

    Do you see a difference between the iridium plug than a regular plug?
     
  5. skyash

    skyash Active Member

    I herd good things and got one for $30 and it's the worst one of the lot never could make it compatible with my bikes. So don't jump on one just yet. Look were your gaps at now and go from there open it a bit and go around the block let it warm up you can take the plug tool and thin flat head or feeler gage with you if it's no good change it back.
     
  6. Frankfort MB's

    Frankfort MB's Well-Known Member

    I use b8hs NGKs and its too cold for all of my bikes so I was going to get a b6 b7 and b5 to see what's best
     
  7. 45u

    45u Active Member

    I run a B7HS gaped to what the book says of around .025. I run a cooler plug then many but you have to under stand I live in middle GA and the tempt here are already over 90 degrees and during the summer it gets up to 3 digits with a 80% plus humility. After over 2 1/2 gallons of fuel run throw her she still has the same plug.

    Now if you are running a hopped up motor with more compression a colder plug might work better.
     
  8. Frankfort MB's

    Frankfort MB's Well-Known Member

    I feel ya im from Kentucky it's not much cooler here, it's a good thing these things can stand the heat;)
    Mine doesn't like the cold though
     
  9. 45u

    45u Active Member

    All my air cooled motors love the cold much better then the hot. I my self much rather have the cold then hot. You can always put more cloths on when cold but you can only take so much off with out going to jail when it is hot. Other then my motor bike my only transportation is my rig (motorcycle with sidecar) as I hate a cage! Been that way for over 45 years none stop. Only time I had a car is when I was raising my children.
     
  10. butre

    butre Well-Known Member

    below 30 and my engines make zero power. all my engines like somewhere between .037 and .043
     
  11. HeadSmess

    HeadSmess Well-Known Member

    never bothered measuring the gap. i just take a peek, see a gap, stick em in... as long as it isnt huge or too small... 0.5 to 1mm.

    it makes literally sweet eff all difference. we arent running points ignition on these things!
     
  12. butre

    butre Well-Known Member

    you'd be surprised. I tried the factory recommended .028 for a giggle once and it just missed and surged and all manner of nasty things
     
  13. HeadSmess

    HeadSmess Well-Known Member

    0.028...lemme see now...

    divide by 25.4, multiply by something um...

    0.7mm? um? thats a standard plug gap...
    or 0.07? arrrrg!

    you know i refuse to follow any plans that are measured in that horrible unit, though i always found it amusing to call a 4x2 a "3 35/64 x 1 49/64"...(finished size is 90x45 over here...)
    the number of customers that were amazed i could use both units (when i worked in a timber yard) was astonishing. but thou just hurts my head... even if my lathe is imperial, i hate it hate it hate it! ever tried cutting metric threads on an imperial lathe? you cant take it out of gear! forwards, stop, backwards, stop, forget to back tool off, snap, regrind tool, re-align tool, snap, repeat process, give up and wait two weeks for a weird sized die to arrive off e-bay... M9x1? wtf?

    nope, i still say as long as its about the same as a credit card is thick...its fine. never had an issue.

    have burnt plenty of ignition coils out by going over 2mm though...
     
  14. butre

    butre Well-Known Member

    it's a standard gap, but it doesn't work well at all in any of my engines. I just did some tests on my race bike and went 50 on flat land with stock gearing using a .039 gap, lost a whopping 5 mph with an .028, and it took me a whole lot longer to reach top speed.

    and then the engine overheated and started losing power, but that's neither here nor there. it's still got my winter plug in it, not too nice when it's 90 degrees instead of 30

    I love thou, it's easy to think in for me. especially gapping spark plugs, one thou in any direction makes enough of a difference that using millimeters or even tenths of a millimeter isn't sufficient, but going down to hundredths of a millimeter just complicates my thought process.

    I can think in either unit just fine but all my precision instruments are imperial.
     
  15. 45u

    45u Active Member

    My little stock motor bike runs great on .025 to .030. It will even pull my 220 pound
    butt up step hills. Never tired a bigger gap but will for the fun of it.
     
  16. butre

    butre Well-Known Member

    I have a 220 pound butt as well, and my bike doesn't notice a difference between it and my racing buddy's 130 pound butt. I actually get better acceleration than he does, because I'm less afraid of destroying the clutch.

    my race bike makes a buttload of power and the top speed is only restricted by gearing. it can damn near climb a vertical wall and and in the quarter mile it outruns some cars
     
  17. 45u

    45u Active Member

    I am getting ready to open my plug up a little to see how it does. Will report back after I test it.
     
  18. 45u

    45u Active Member

    Butre are you running a stock or up graded CDI? I am guessing up graded. The one on mine right now is stock. Only thing on the motor that is not stock I am running a SHA clone carb. Changed the gap from .025 to .032 took her for a 4 mile ride. It seems to have better low end torque but might be lacking on top end torque a little but not 100% sure. Idles the same very good. Have the fan on it going to try opening it up to about .038 to see how she does. I am running a NGK B7HS.
     
    Last edited: May 13, 2016
  19. 45u

    45u Active Member

    My SHA carburetor clone works fine for me been running it for over 2 1/2 gallons. Did you try changing the jets?
     
  20. butre

    butre Well-Known Member

    stock. none of the aftermarket CDIs are built for 11500 rpm. I use a jaguar on my street bike which only turns around 9800.
     
    Last edited: May 13, 2016
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