head studs

Discussion in '2-Stroke Engines' started by mrsaxman99, Apr 21, 2007.

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  1. mrsaxman99

    mrsaxman99 Guest

    can anyone hook me up with the length, width, and thread pitch of the head studs? I stripped one of them, and plan to Helicoil it (JBweld held up for about 10 minutes). Just need to figure out the bore-over size and what direction I should go.

    thanks in advance!

  2. JosephGarcia

    JosephGarcia Guest

    I took mine to this autoparts store that had many, they seem to be a standard in most cars as well. Got it replaced with a longer one for cheap, going somewhere that deals in bolts for autos might help you with finding that info
  3. gone_fishin

    gone_fishin Guest

    i don't have that info, either...that's why i'm gonna ask you to post it when you do find out :)
  4. mrsaxman99

    mrsaxman99 Guest

    haha okay augi :)

    Everyone talks about stripping the intake/exhaust/head studs, but I definitely have stripped the "receiving end" on the block itself...of course the worst situation.

    JBWeld didn't work, so I plan on using a Helicoil to make new threads. If anyone has had any experience doing this PLEASE post up.
  5. srdavo

    srdavo Active Member

    could you tap it out to 1/4 inch "USA" thread?
  6. mrsaxman99

    mrsaxman99 Guest

    Well my actual head stud is fine, so I'd want to keep using that so I don't have to buy new hardware. The helicoil allows you to drill out the hole, put this metal insert in there, which brings it back to its orignal thread size.
  7. Not sure if you have this info by now but in the kit I got it is a 8mm bolt with 1.0 pitch.

    Unfortunately the standard for 8mm in Australia in stainless steel is 1.25 and the fastener shop did not have the 1.0 listed.

    My block has just stripped and I need to helicoil it. I have never done this so it is going to be another lessin in life! :grin:

    I searched on helicoil and found all the info I needed at MBc however and that is how I ended up at this post!
  8. MikeJ

    MikeJ Member

    I have the same dilemma. I stripped a 6mm stud and block threads right out of the block. (Should have stopped torqueing them down when I reached 9 ft-lbs.) I am going (in the near future) to drill out the block with a 17/64 inch drill and tap with a 5/16-24 NF tap. Then use some antisieze compound when tightening it down. I did some stud diameter math, and it seems to me that installing an 8 mm stud will not provide enough thread grip (at least, not to satisfy me). My method will provide fresh holes with full depth thread grip. I have not heard of anyone using my planned technique; it may fail. Will keep everyone posted of the results, be they good or bad. (Who said a Chinese engine must be all metric, anyway?)

    I am going to use US Grade 8 engine quality bolts. It strikes me that stainless steel is too brittle for high vibration environments.

  9. Just_Gasit

    Just_Gasit Member

  10. bootlegger

    bootlegger Member

    I just helicoiled my block. I managed have some 8x1mm coils in the tool box. If you have no luck turn the studs over and helicoil with the coarse thread on that end. The coarse thread will hold better in the alloy anyway.
    By the way I retapped the back mount holes 5/16 unc and the front mounts 1/4. I had all sorts of problems before with the fine threaded metric stuff.
  11. Bryan Smith

    Bryan Smith Member

    most of the 49/50cc engines use 6mm x 1.0 pitch.
    some of the 66/80cc engines use 8mm x 1.0 pitch
  12. Nitropeewee

    Nitropeewee Member

    heli coil all the way did it with mine. u want the 6.6mm helicoil got mine at atou zone kinda expesive but works great! make sure u dont get any metal shavings down in yer motor though. good luck.
  13. E J

    E J New Member

    Time sert is the best! (don't monkey coil it) they are not cheep but you woun't have to do it again and if ya JB weld it in like I did on my harley I don't think I will ever have a problem with it! coils are ok for things that don't need torque. listen to the old bikers LOL :grin5: