Snapped head bolt PLEASE HELP!!

Discussion in 'General Questions' started by brendonv, Oct 4, 2008.

  1. brendonv

    brendonv Member

    Man i new i shouldnt of touched it but i did, my head was loose and wen i pedaled it made a hiss sound. I tried to tighten the bolts ( not with a torque wrench ) to see if i could close the gap, then im tightening the bolt more and there goes a bang, the top of the bolt gone. Snapped off, what do i do im freaking out, i just got my engine as a birthday pressie, i loved it, just tightening all the screws and things, try tighten the head bolts and bang it snaps. There is still a bit of thread sticking out if i take the head off so lets hope i can take it out with some pliers. Im also freaking out because if i tightened it that tight i may have stripped some thread inside. OMG im so scared, i just want to ride it. Why did i do that man, i hope i can fix it by buying a new bolt. Please tell me how to fix it. I heard people change all the head bolts to high tensile ones anyway so maybe they were **** quality bolts, if i get it out then ill change em all around if thats the case i just need some1 to tell me its fixable and i didnt just f*** up the engine, please help.

  2. fetor56

    fetor56 Guest

    Scroll down to the bottom of the page & refer to Similar Threads.If unsuccessful there do a search.....i know it's a hassle but it's a good way to learn.
  3. brendonv

    brendonv Member

    I have two options, first take the whole head off, cut a slit in the thread and use a flat head to remove. Second option is buy a removal kit like ezy out i think there called but thats the more expensive option. Then since im taking it all off it gives me a reason to change all head bolts to high tensile (stronger) ones. My only worry is will i need to get a new gasket? Ive only been riding the thing for about 60-80mins all up, do i need a new top gasket? The bottom one should be fine but i heard once the metal one has been compressed you shouldnt reuse it or ur creating more problems than your fixing. Any things i should do while the head is off? Should i locktite the head bolts in or oil them or anything? Anything i should do while its all opened up. I think i no why it snapped, i didnt tighten them the second time in a criss cross fashion i just tightened one wen the one on the other side also needed tightening so i was tightening it while it was on a slight angle which i think is why it snapped. The snap is on a slight angle so i think that was my problem. When i tighten them again ill tighten them like this: 4ft/ lb, 8ft/lb 12 ft/lb and in a X pattern.
  4. BSA

    BSA Guest

    Take the head off, get a pair of mole grips (vice grips in the USA), grip the threads and screw them out. You might aswell replace all of them. Jam two nuts into each other to screw the new studs in, I use loctite blue that way they can be replaced easily, if you use anything stronger you may have to heat up the stud should you ever need to replace it again.

    BTW: I always cut up M6 allthread to replace studs, i woulnd't bother buying a new stud from a vendor.

  5. brendonv

    brendonv Member

    but mine are like a full bolt, cant i buy long M6 bolts to fit? getting a thread screwed in there then putting a nut on top seems hard.
  6. BSA

    BSA Guest

    It's not difficult, if you did use a bolt it would have to be Exacltly the right length, better of using thread and nut.

  7. brendonv

    brendonv Member

    so locktite the thread in then locktite the nuts on then cut of the excess thread then start torquing.
  8. BSA

    BSA Guest

    yes, but if you can make the new studs about the same length as the old one, that way you don't have to cut of excess with the head on (which is awkward)
    Don't forget to use beefy nuts, perhaps reuse the old domed nuts.

  9. brendonv

    brendonv Member

    yeh ill get some beafy locking nuts.
  10. arceeguy

    arceeguy Active Member

    Buy or borrow a torque wrench too. 10-12 ft-lb is not a lot of force, but that's all you need. Remember that when the engine warms up, the head and cylinder will expand a little, making the actual torque higher. I set the torque wrench to 4ft/lb, tighten in an X pattern, then 9ft/lb, then 12ft/lb. On one engine, I found that the acorn nut was bottomed out but the stud was loose. On all of my builds, I have replaced the acorn nuts with metric nuts and copper crush washers. I have kept the stock studs, and made sure they were threaded all the way into the crankcase and used thread locker on all the hardware.

    Good Luck
  11. Mountainman

    Mountainman Active Member

    impressive -- these guys have it spelled out well for you

    vice grips -- used very often -- if we just have a little something to grab on to

    ezy outs -- when we have right size available -- great tool -- not very expensive

    new quality head bolts -- I would torque more times than mentioned above
    4 8 10 12 ?? doesn't matter that much

    a new head gasket is always a good idea
    if one can not be found in time
    someone on site mentioned some spray (copper spray) from auto store
    this was sprayed on to old gasket I believe -- they said worked great still holding
    note -- new gasket would be best..

    hope you are up soon so as to Ride That Thing -------------------MM
  12. brendonv

    brendonv Member

    Alrighty guys, its all fixed and working better than b4 now because, the head wasnt actually perfectly flat! We will get back to that in a sec but first off, i made a new thread to put in there by getting 8mm rod and cutting 6mm threads on either end, if u use 6mm thread it is loose in the barrel so i used 8mm for a snug fit. Then my dad checked the gasket and it was still fine so we put the head back on and locktited it all to find a gap still. I started her up and if u put your hand in front of the gap there was a lot of air coming out, my dad said "it looks like ur head is warped" so we took the head off again, got a sheet of glass as its pretty much the most flat thing u can get and put the head on there. Usually you put a bit of jiff on the glass, put the head on the glass and get the jiff on it then press the head on the glass again to get an imprint of the head to see what imperfections it has. We didnt have any jiff so we got the finest wet and dry sand paper we had, put it down on the glass, put a bit of CRC on the sand paper and started to slightly sand the head moving the head in a circular motion. We turned the head over to find two sides of the head shiny and the other two not which means the head wasnt even flat which is why it was leaking. We sanded it a bit more until it was all shiny and then put it all back on. The engine now runs quieter and better than ever and no leaks! We ran the engine for about 15mins until it was real hot then tightened the nuts again. Its working real great now and i fixed a few other things around my bike.

    Just to let u guys no, i didnt do any of this. my dad did as he's been riding motorbikes for over 35 years and has pulled a few engines apart in his years, he fixed it all and gave me a bit of knowledge along the way. Im really happy now, its working great. Im a happy boy and now my bike is working better than ever and ready for many days of riding.

    Thanks for everyone's help, its also handy to know im not the only one that has done this after a quick google search on snapping head bolt and seeing mine was only very minor compared to some guys that snap a bolt half way through there block on a expensive car engine.

    Cya guys, ill upload a few pics of the head n stuff i took with my phone, not the greatest pics but its all i had at the time to take pics.

    From Brendon.v

    UPDATE: Added pics!, as you can see by the second last pic the thread on the far right is a lot shorter as it snapped. Not anymore!

    Attached Files:

    Last edited: Oct 5, 2008
  13. DeusIgnis

    DeusIgnis New Member

    Ive snapped a head bolt before.

    Not hard to fix, get some high quality m6 threaded steel (also look at replacing every bolt on your engine with this as the chinese stuff is ....). Get hacksaw/grinder and cut to length.

    getting old one out for me was easy, pliers got it out.

    Others have given solutions for getting it out, replacing it is easy.

    I recomend keeping a good stash of m6 threaded steel and nut/washers etc on hand for these type of situations. I dont trust any of the original fixings that come with these engines.

    EDIT: sorry, resurrected this thread by accident