Can't find headbolt helicoil

Discussion in 'Frame Mounted Engines' started by Patch, Jul 25, 2007.

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  1. Patch

    Patch Guest

    I can't seem to find a M8-1.0 helicoil kit around here. I did find a M8-1.25.
    The m8-1 is a find thread with the 1.25 is coarse. Online the fine threaded one is $50-sum but the coarse one is only 20 over at Ace.

    So I come to you asking... would be ok to switch just one head bolt out for a 1.25 pitch thread? it still has the same diameter just different thread size, right? :???: and could I get a bolt thing that is threaded all the way up or does it have to have the smooth part in the middle?
    This way, I can save time and money to just buy the cheaper and available Helicoil and just replace one stud. :)

    PS having only one of the four studs "helicoil"ed and a different pitch won't cause catastrophic failure, will it? Thanks for reading my long and boring post :D

  2. locoWelder

    locoWelder Guest

    go for it patch ,it will work fine and you can use allthreed
  3. Patch

    Patch Guest

    Thanks Loco, Ill try that hopefully tonight...almost solved. Just alittle testing to do. :D
  4. Did the very same thing through this week.

    I could get both 1 and 1.25 pitch helicoil but I could not get stainless threaded rod in 1 so I just bought the 1.25 helicoil and rod.

    I will hopefully get some time this weekend to attempt the fix.

    With my motorcross bike the head bolts have thick copper washers under them without a lock washer. I am thinking these washers expand quickly with heat and therefore lock the nut??????? Your the metal man loco what do you think :?

    Getting thick copper washers is proving to be difficult so I may have to go get the same part as the motox bike.
  5. Patch

    Patch Guest

    Go you good thing... where did you find a M8-1 helicoil? Most suppliers don't have them becuase its an odd size to stock. Where did you find it...advanced autoparts or something? thanks
  6. I got it from what I would consider a specialist supplier called Car Parts Plus here in Lonsdale South Australia. I found this place as my car mechanic gets his parts there so I figured they must be good. :grin:

    When I spoke to them on the phone they said they could get the 1 pitch but they would have to order it in.

    When I picked the 1.25 kit up it was not the Helicoil brand it was a Recoil brand. They where only two thirds the price however so I thought I would give it a go. When I open the package maybe tomorrow if I find any website for Recoil I will post it here.
  7. srdavo

    srdavo Active Member

    my 2 cents

    why not re tap the 6mm hole to 1/4" & replace the stud.

    or maybe 7mm? new studs are WAY cheaper than helicoil
  8. srdavo the head bolts are 8mm diameter by 1 pitch as standard.

    We are having trouble getting this size so the 8mm x 1.25 is available.

    I have just looked up the tech manual for Recoil and it does not have the M8 x 1 option so the guy at my local auto parts store is either incorrect or has something else in his mind.

    I will call him on Monday to see if he can get the 8 x 1.
  9. srdavo

    srdavo Active Member 48cc and 55cc engines have 6mm head studs. I just went out to measure them.

    :???: my bad.... carry on, gents
  10. I have just noticed that both Patch and I are running 70cc so I am not sure what the others are. Anyone here have any idea if they are all 6mm?
  11. azbill

    azbill Active Member

    yup 6mm 1.00 pitch
    headbolts are 8mm 1.00 pitch :cool:
  12. srdavo

    srdavo Active Member

    so, what you are saying is the headstuds on a 70cc are 8mm. what size are the intake & exhaust studs on a 70?
  13. gone_fishin

    gone_fishin Guest's more complicated dax 70 has 8mm headbolts, other "80's" are known to come with 6mm...etc...and so on...

    dax 70: mount/intake/exhaust studs= 6mm
    head studs=8mm
  14. Ok so today I fixed the head bolt that was stripped by putting in the helicoil that was 8mm x 1.25pitch. I was also going to install helicoils in the other three but noticed they are closer to the cylinder than the one I had just fixed.

    They are so close that I am concerned that if I drill the 8.3mm hole that is required for the helicoil then this will severely weaken the wall of the cylinder. Without measuring it I guess it will be only 1mm or less when drilled.

    I could just leave the rest as they seem to be holding ok but I wanted to replace the 8mm x 1pitch iron studs with stainless but as mentioned before I can't get that size.

    Anyone else drilled that close?