Spark plug hole repair.

[FLHGSRay]

I've seen this question come up a few times, so I searched for an article I'd seen in my MC Classics mag. Seems like it would work pretty well. Never tried it myself. Admin can feel free to move it anywhere or sticky it or whatever.

http://www.motorcycleclassics.com/mc-how-to/spark-plug-rethread.aspx#axzz2xUx6uaHF

 

[850 Combat]

I used one on a GS850 I threaded it in in a few more steps, removing, cleaning and regreasing the threader a few times as I went in with it. Also held a piece of copper tubing in my shop vac using a rag, and vacuumed out the cylinder. So far so good, but its only got a few hundred miles since then. No plug changes, ha ha

 

[chuck hahn]

I did number 3 on my 78 1000C a few years ago using the NAPA Save-A-Thread kit. Did it on the bike and sucked the cylinder out with some tubing and the shop vac like was mentioned. Put the plug in and rode away. No problems since either.

 

[Rob S.]

I stripped a hole on my Z1, a guy put an insert in, said something about rotating the crank so that when it started any debris would be blown out with exhaust.

Worked okay; lasted the next few years I rode the bike.

 

[Scratcher09]

If your threads are not mangled all the way through, this tool works great and does not require an insert. I used it on a hole where the first 20% of the threads were mangled. This tool goes into the hole and you twist the bolt that goes down the center which expands it. Once expanded, you pull out wards till you feel it engage on the good threads. Then you twist it out and it cuts the bad threads on the way out. It worked great and using grease with it kept any shavings from going into the cylinder. The key is it needs good threads to start on (from the inside) so if your threads are trashed all the way through to the chamber then this can not be used.

http://www.amazon.com/Powerbuilt-640811-Back-Tap-Thread-Repair/dp/B0014FGVVW/ref=pd_sim_sbs_hi_1?ie=UTF8&refRID=1F8C2F15KYW0G8G401CD

 

[Hedonaut]

I'm a huge fan of the Heli Coil. I put on in to replace a glow plug hole I had to drill out on my old Mercedes. It held up nicely. If it will hold against a big 6cyl diesel, it'll hold a sparkplug in a bike any day.

 

[FLHGSRay]

I've seen hundreds of tooling fixtures and things in industrial settings put together with Heli-Coils. They hold up well. I wouldn't hesitate to use one on a spark plug hole.

 

[Griffin]

I've repaired a couple spark plug holes with thread chasers. They work if the threads aren't too mangled. Heli coils work too.

The good/bad thing about the aluminum alloy used for these engines is that it is very soft, probably the softest stuff I've seen used in the automotive industry. It probably was selected for it's heat transfer abilities, and the lack of wear it puts on tooling when being machined. It is very easy to "clean up" boogered threads in, so long as there is still something there to work with.

 

[60ratrod]

I've helicoiled sbc aluminum intakes and transmission cases with excellent results. since the insert is made of steel, it makes for a stronger threaded hole