Stripped Spark plug thread solutions?

Discussion in 'Engine, Fuel and Exhaust' started by 09GLDR, Jun 27, 2010.

  1. 09GLDR

    09GLDR Member

    Ok guys, my girlfriend has a 05 Dyna with the 88ci (platinum finish motor) and the rear cylinder head spark plug threads are shot! Can't run a thread chaser the threads are too boogered up. My question is do I use a insert (heli-coil) or have a machine shop re-do it? Or any other suggestions or ideas would be greatly appreciated! Its been up on the lift for a week now, and she's getting a little...we'll you know!
  2. glider

    glider Veteran Member

    Depending on your talents, you may be better having the machine shop do it if you aren't secure with doing the repair. It's not a difficult thing to do but you only usually get one chance at it.
    Helicoils work well for this application as do Time serts too.

    Thread Repairs - Harley Davidson Community
  3. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

    If you decide to go ahead and repair yourself make sure you have all the correct tools for the job before you start
    normally you can buy a kit with everything you need to do the job
    i bought a helicoil kit for a similar job but it did not have the correct drill bit in the kit and i had to make a separate purchase
    i would always remove the head and do the work on the bench as you will get better light and more able to get the angle of the drill correct also all the swarf will fall on the bench rather than down the cylinder
    the one i did held up for a couple of years until i sold the vehicle on and i lost track of it
    if you were in my area id say bring it round as i still have the kit and want to get more use out of


    NEWHD74FAN Experienced Member Retired Moderators

    As most have stated you have options depending on your skill level and confidence. It is a common occurance on Honda auto engines for the plugs to "blow out" of the hole taking the threads with them due to high compression and very little threaded area. I was just thinking how much "meat" is threaded in Harley heads, and how often does this stripping thread thing happen on Harleys? (I have seen plenty of telltale dented hoods on Preludes, Accords and Civics).
  5. 09GLDR

    09GLDR Member

    I agree with you guys. The more reading I do, the more I'm leaning towards having a machine shop re-work it or find a new head for it. The slighest error will cause me to have to replace it anyway. Thanks guys!

    BUBBIE Well-Known Member

    I will Suggest to USE anti seize or copper grease as some call it...
    A little will help keep the head threads in better shape from the in and out needed to clean and inspect plugs often..

    signed....BUBBIE :D
  7. Jack Klarich

    Jack Klarich Expert Member

    Any good machine shop I E head service shop can do the proper repair and it will be right, always use anti seize and start the plugs by hand and torque them, this is one of the down falls of aluminum heads, and as NEWHD said about the Honda cars, been there done that one too, Good Luck:D
  8. Ride4Two

    Ride4Two Member

    Are you physically removing the head for repair? If so, depending upon how worn your original thread pattern is, you can utilize a "Good" helicoil. Please let someone do it properly if you have no experience. I have been in the maching business for 25 years and have seen the pitfalls of most situations.
    As most have said, pull the head off and have some one do it if you are not familiar with installing of helicoils or inserts. I do not suggest performing this action while the head is on the bike. I have seen it done, but like what was stated before, the metal that is removed from the re-tapping / enlargement of the thread for the heli-coil will definately fall into your cylinder, causing a MAJOR problem.
    I know its a pain in the (EDIT), but taking the time and doing it right the first time will save you alot of grief. Been their done that.
    Just my 2 cents.
    Please follow all insructions that have been given by the gentleman prior to my post. They know as well as I do. HTH with your decision.

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  9. 09GLDR

    09GLDR Member

    Crazy week, but finally got around to removing the rear cyl. head. Thank you guys, for all the replies, I'm not afraid to turn a wrench on a Harley, but I normally don't get into the motor's internals. This was my first head removal and it wasn't as bad as I thought it would be. I had a dealership tell me that they would send it (the head) to a machine shop, where they would "add material by welding it in and then re-thread the plug hole". So I called some machine shops around here and all of them said "they have never done that and what they can or would do, is an insert. With all the advise you guys have given me I think i'm gonna have a shop do the insert. With that being said, besides the proper loctites, torque values, and gaskets, does anyone have any special tips on reassembling the head after I get it back? The push rods were removed in the "unloaded" state and piston at TDC. Here are some pics and thanks again guys!

    Attached Files:

  10. 09GLDR

    09GLDR Member

    One more thing, is there a difference between the Time-Sert and the Keensert products? Or are they the same thing, just different vendors?