Helicoil question

[apriliars250]

i need to repair my spark plug thread i have the right size helicoil M10 x 1.00. i need to know what tap size and drill size i would need to use. i have the tool and brerak pin tool from a kit i used before.

[bob_e95482]

Usually a helicoil will be sold with the Helicoil tap. The helicoil tap cannot be used for any other thread. Also, a helicoil is not the best repair for a spark plug thread. The better repair would be a Keensert or Timesert.

[apriliars250]

i know timesert is better my mate has use helicoil for his spark plug befor and had no problems...lots of people have a different answer what is better

[1987CR250R]

Drill size will be 13/32.

[schrode]

what kind of bike are you talking about? i have several bikes and not all the plug threads are the same size.

[1987CR250R]

Yeah because most dirt bikes use a 14mm thread for their plugs. The only ones running the small plug are the inline 4's.

[schrode]

Yeah because most dirt bikes use a 14mm thread for their plugs. The only ones running the small plug are the inline 4's.

i'd probably avoid making blanket statements such as the bolded ones.

my xr 400 runs the smaller threads as does the wifes and kids smaller bore bikes. my smokers and v-twin all run larger, 14mm threads. i think the 'berg does to but honestly i haven't pulled the plug on it yet.

[apriliars250]

its a drz 400

[apriliars250]

i have done some more searching and asking people who sell helicoils and alot of them dont know 100% if they are the same tap size as a normal tap or the say they are

one seller who sounds like he knows 100% said

Hi,

Yes they are oversized to allow for the insert. An M10 1.0 helicoil tap has a diameter of 11.3mm

[1987CR250R]

Don't drill your hole to 11.3 mm. The hole needs to be smaller than the diameter of the insert so your tap has something to cut threads into. Like I said, hole diameter for a 10mmx1.00 helicoil insert is 13/32.

[hi_im_sean]

i have done some more searching and asking people who sell helicoils and alot of them dont know 100% if they are the same tap size as a normal tap or the say they are

one seller who sounds like he knows 100% said

Hi,

Yes they are oversized to allow for the insert. An M10 1.0 helicoil tap has a diameter of 11.3mm

helicoil taps are special. they are not common thread sizes they are specific to the helicoil you are using, your not going to pick one up at home depot by itself, youll have to rebuy the whole kit. and uh... the kit has everything youve asked for in this thread and more.

[Chuck.]

My first put would be to chase the thread with a tap. If that doesn't fix the problem then a Helicoil would be the next step. The Helicoil is a steel thread insert that uses an over sized hole and an oversize tap that is the same thread pitch, and then installs a diamond shaped thread into the new hole. The result is a steel thread for the original bolt, or plug.

The inserts such as Keensert use a much bigger hole and install a steel insert that has a threaded bore.

For plug repair I favor Helicoil, a tried and proven method of improving threads in aluminum from WWII.

[W R]

i need to repair my spark plug thread i have the right size helicoil M10 x 1.00. i need to know what tap size and drill size i would need to use. i have the tool and brerak pin tool from a kit i used before.

You have many reply's on this thread and most of them are saying the same thing. Bottom line is if you are going to use a Heli-Coil for this repair (a good fix in my opinion) do not do it unless you have a Heli-Coil tap made for your m10 x 1.00. There are no other taps that will work in place of this. The Heli-Coil tap is made specific for their product. If you had a kit before you should have a tap that says Heli-Coil M10 x 1.00 but will be oversized for their insert.

[1987CR250R]

The taps are specific because they have to fit the larger diameter of the insert and maintain the same thread pitch of the original fastener. However, regardless of the brand of coiled insert (Helicoil, Permacoil, Recoil, etc...) the taps and inserts are all compatible.

Understand, the cost of the insert, in that size, is typically between $.50 and $.75 a piece. The kit costs $30 because of the custom ground tap.

[huskyfrk]

helicoil is so old school. no need for a special tap with the keensert. std threads, a larger hole, but a better quality repair.... IMHO

[1987CR250R]

helicoil is so old school. no need for a special tap with the keensert. std threads, a larger hole, but a better quality repair.... IMHO

Big trouble with spark plugs is heat transfer. They cool to the head. Keenserts are thick walled which isn't so good for cooling. But... are Helicoils better for cooling?

The world is a funny place, the aircaft world swears by helical inserts as they are a proven technology. No critical bolt on an airplane goes directly into aluminum, every hole has an insert.

On the other side of the spectrum, working on Electromotive Diesel engines, every thread repair I have come across spec's a Keensert. I recently had to install 32 Keenserts on the exhaust deck of an EMD. That was a miserable job.

Oh, if you use a Keensert, make sure you use the drill spec'd by Keensert and not the drill spec'd for that recommended tap. Keenserts don't use a fully developed thread and the holes need to be drilled oversized.