Straight spark plug head

Discussion in 'Performance Mods' started by Frankfort MB's, May 22, 2016.

  1. Frankfort MB's

    Frankfort MB's Well-Known Member

    what spark plug should I use with my straight up spark plug because my b8hs NGK will not work with my high performance head due to hitting the spark plug

  2. Steve Best

    Steve Best Active Member

    edit: WHOOPS! Will not work, it is an "E" reach, not and "H"
    I use these on my KTM to clear the fuel tank.
    I do not think there is a BR8HCM, but it would be what you are looking for.

    Denso makes short plugs as well, Denso IWM01-29 was a replacement for the BR8ECM.
    Brace yourself for the price!

    (Previously posted, NOT VALID)
    Use a BR8ECM.
    Pricey, but shorter on the top side for more clearance.
    The inside the cylinder part is exactly the same.

    Last edited: May 22, 2016
  3. Frankfort MB's

    Frankfort MB's Well-Known Member

    I just read my post and realized I made a mistake in what I said. I need a plug that is shorter because piston is hitting the plug
  4. HeadSmess

    HeadSmess Well-Known Member

    ha ha...shoulda left that one, cus the original post dont make sense anymore...

    plain old CJ8 /bmr8hs for lawnmower/brushcutter/most small yard equipment works fine when space is tight.
  5. Frankfort MB's

    Frankfort MB's Well-Known Member

    Lol sorry not very good at explaining myself when I'm kinda confused on what I'm asking? ;)

    I'm using a head that has the spark plug straight up and the tip of the spark plug is hitting the piston

    Attached Files:

  6. HeadSmess

    HeadSmess Well-Known Member

    its either an E thread length (19mm) or its a P tip(projected).

    the cj8 is actually slightly better than the b5Hs as the thread is marginally shorter, about one thread less...
  7. What's best plug for 49cc 2stroke (B5HS) B6HS (B7HS) ? I'm also having a problem with my car when I pull in the clutch it revs really really hiigh
  8. HeadSmess

    HeadSmess Well-Known Member

    its climate dependent. 5 is the best for all round, 7 will tend to foul up/ come out dark brown black unless the engines tuned well and ambient temps are high...

    otherwise all the same...

  9. Typo car should be CARB DOHHHHHH!
  10. Steve Best

    Steve Best Active Member

    You need to learn how the read the heat range on the plug. Read my other threads.
    Too low a number is dangerous. Stick with a 7 or 8 or you may burn a hole in a piston.

    Your car either has a vacuum leak or the idle valve solenoid is dirty and sticking.
    Buy a can of throttle body cleaner to solve both.
    Clean the throttle solenoid then hunt for leaks. A small hose will work as a stethoscope.

  11. I've read your plug (or o should say I looked at it) I sometimes have trouble understanding things on paper. I have swapped out carbs completely still have problem.
  12. Ill get to the bottom of it
  13. Its a air leak in the carby intake. I've already made a gasket I willl put it on tomorrow. Made out of metal tape layered upon layers.
  14. butre

    butre Well-Known Member

    yep, unfortunately that damn nipple doesn't unscrew like an NGK does. doesn't work with my plug boot
  15. HeadSmess

    HeadSmess Well-Known Member

    ive got an elderly cj7 that does unscrew...yerp, dont think i have seen any small engine plug that unscrews in ages. approved for aircraft use ;)

    swap the boot for one off the brushcutter, they have that funky spring brass bits to vibrate apart! no threads at all...

    or use the entire lead and boot off a car.

    *has mental image of someone sticking rear panels of car on doesnt fit!*

    trunk? we call em the boot :) no idea why...boot. where the f did the name boot come from?