Topic: Poss spark plug issue

[sky56]

Hey everyone. Helping a friend with his 78 cb750 k and as we were doing the spring tune up he turns to me and says this one spark plug is going in funny? I said did you start to put them in by hand assuring they went in smooth. He says yes. Upon investigation it appears that a little down the plug hole it appears to cross threaded. The plug goes in over half way before it becomes affected by this. He said it felt like it came out smooth like the other 3 and the all 4 old plugs appear to have the usual wear you'd find. So my question is what's the next step? The motor runs nice and the bike is great. We haven't done anything to it since discovering it yesterday. Any help would be great. I was thinking a tap and die but did not even try that yet. I figured il let you guys the experts chime in. Thanks guys in advance

[flopshot]

without seeing the threads i would say to run a grease coated thread chaser through.   don't use a tap unless you've "worn" the thread cutters a bit.

[sky56]

Sounds good but what in the world is a thread chaser? Thanks man

[chickenman_26]

Sounds good but what in the world is a thread chaser? Thanks man

This is a thread chaser. http://www.usatoolwarehouse.com/usatoolwarehouse/KAS-1013A-p-KAS.html A chaser will massage slightly damaged threads back into shape and remove carbon, etc. It won't remove metal like a tap will, so the threads won't be too loose afterward. You're only going to get one shot at repairing the existing threads, so I suggest not doing anything with that hole till you get one of these.



Stu

[sky56]

Awesome thanks. I will def be looking at getting one of those asap. Be a nice addition to the tool box. Thanks again

[Duanob]

Don't forget to grease it up. that will catch the shavings from going down onto the piston. yes there will be a few shavings.

[sky56]

Is there a specific type of grease I should use? Just want to do it right. Thanks guys

[Duanob]

Axle grease is good. Thicker the better. It's only for catching any shavings that come off the thread walls.

[sky56]

Picked up a thread restorer kit from craftsman and it worked like a charm. Thanks for the help everyone