Spark plugs

Hi, can anyone tell me what size tap I would need to clean up the spark plug threads on a Kz750n1 spectre 1982? Thanks

Is this the correct size?

Yes! M14 X 1.25 mm

A thread chaser would be better than a tap. It takes out less metal.

www.amazon.com/Lisle-20020-Limited-Access-Spark/dp/B008MFR2IS

Just sent for this.

Be careful how you use it....

Rick H.

Hi, grease in the flutes and only start by hand till it finds the thread, you tube advice.

I back the tap up and out of the hole often to clean debris off the tap and re-grease if needed. The less junk on the tap the less chance of something getting in the bore. If possible use a tap handle to help keep the tap straight . I usually put the piston at close to TDC so I can peer in the hole with a pen light and see if any junk fell on top of the piston. Just don't bang your tap into the piston. If debris does fall in the cylinder you can try to vacum it out or use a long Q-Tip with a little grease on the end to retrieve the debris. Itty-bitty debris usually blows out, but big chunks can cause problems.
Good luck!
Rick H.

You can put a few greasy gun cleaning patches on top of the piston to attract metal droppings.

All sounds like a lot of faffing to me. Why not just use a reverse action thread chaser. Goes through the plug hole, expand it and unscrew it. It brings any cut material out with it and nothing can drop into the cylinder as the expander plate is the internal thread size.

www.amazon.co.uk/Sealey-MS003-Reverse-Ac...Thread/dp/B0086306NO

Yeah it's a little more work than most people might do, but invariably two things happen in these instances. One is they occur at the worst possible time and second I keep forgetting to obtain one of these expanding spark plug thread chasers. With my luck I would buy one of these tools and would never have a need for it, or it would be so far in the future from when I bought it I would forget I had it. It does sound like a nice tool to have though.

Rick H.

What they are especially useful for is cleaning any carbon out the threads after a colour tune. Don't know why colour tunes have such short threads leaving half the cylinder thread exposed to combustion gases. Use a colour tune alot more frequently than having to repair threads.