Spark plug tap

[knotzilla]

One of my plugs goes in a bit too tight. Luckily I got the plug out. The threads are not galled up in the head. What size and pitch of tap would I need to clean up the plug hole? Thanks Ted

[earlfor]

One of my plugs goes in a bit too tight. Luckily I got the plug out. The threads are not galled up in the head. What size and pitch of tap would I need to clean up the plug hole? Thanks Ted

Which bike?

E.

[bwringer]

The 850G spark plugs use a very common 14mm X 1.25 pitch thread.

You can get a spark plug thread chaser in any auto parts store -- it's a bit like a tap, but less aggressive and works better to clean up bunged up threads.

Most thread chasers I've seen have one end thats 14mmX1.25mm, and the other end is 18mm.

[Steve]

Just be sure to smear a LOT of grease on it to catch the chips before the fall into the cylinder.


.

[bwringer]

Just be sure to smear a LOT of grease on it to catch the chips before the fall into the cylinder.


.

Yes. Do that. :-D

It's also a good idea to improvise something with a piece of tubing, some duct tape, and a shop vac that you can use to stick down through the freshened spark plug hole to vacuum out any chips in the cylinder.

Or, if you have a spare $80 lying around, the Back-Tap looks to be a great product:

http://www.back-tap.com/

[knotzilla]

Thanks, I bought a chaser for $10 bucks and it did a great job. Ted

[argonsagas]

Actually, I do have a real chaser, but when I did not have one I used a grindstone and an old spark plug to make one.

Lightly grind the bottom threads of the plug, as evenly as possible, and be sure they are tapered inwards as you do this. (narrower at the bottom end)

Then, using the side of the grindstone, cut a vertical notch into the plug , making it as sharp an edge as possible.

Tuck a small piece of oiled cloth under the plug tip and you have an instant chaser that will pick up most of the debris that may come from the work.