Topic: CB400F plug #2 angle

[rhauff]

I recently inherited a free CB400F.  It came with all the typical attributes of a free bike, plenty of rust and a box of parts that had been removed while trying to make it start years ago.

Plugs 2&3 were out when I got it, 3 went in fine, but #2 is threading in at quite an angle to the outside, and not centered left-right in the cavity in the head.  I stuck a tube, the same size as the plug seat, down in just to check which way the seat faces & that seems to be perpendicular to the cavity, but the actual hole is tilted toward the left.

My first though is that the hole got severely crossthreaded & started to try a bottom-up thread chaser but the threads seem to be consistent all the way to the bottom of the hole.

Does plug 2 lean further to the outside than plug 3?

Thanks for the help!

[Gorwoc]

That doesn't seem right but you say that the treads felt clean.  Can you get a small light and maybe a pocket scope to the hole?  I'm wondering if someone helicoiled it with a hand drill.  Close inspection should reveal the helicoil end. That would be a bummer. But I had taken the plugs out of mine so I went out and put 2 & 3 in and there is indeed an outward angle to the plugs. 3 is obscured by the tack cable so it may not seem as much as 2 but I'd still look for the helicoil, it was a more common butcher solution back when.