Topic: CB350F Exhaust Stud

[CT]

Howdy!  Quick question that seems simple, but I can’t seem to find an answer for.  Along with many other bolt holes that were cross threaded y the previous owner, one of them is the hole on the head for the exhaust stud, which is thoroughly chewed up.  I’ve managed to get an exhaust stud, which to my knowledge is an M6x50.  I’ve had some luck throughout this process of using new OEM bolts on the cross-threaded holes to essentially thread chase them with the bolt back to how they should be, but I’ve had no luck with this one.  I’m now looking at buying an actual thread chaser and should that fail, a time sert kit, but I don’t know the thread pitch of the exhaust stud.  Could anyone help me with, and moving forward is there a way to obtain this information on my own?  Thank y’all very much in advance.

[HondaMan]

Howdy!  Quick question that seems simple, but I can’t seem to find an answer for.  Along with many other bolt holes that were cross threaded y the previous owner, one of them is the hole on the head for the exhaust stud, which is thoroughly chewed up.  I’ve managed to get an exhaust stud, which to my knowledge is an M6x50.  I’ve had some luck throughout this process of using new OEM bolts on the cross-threaded holes to essentially thread chase them with the bolt back to how they should be, but I’ve had no luck with this one.  I’m now looking at buying an actual thread chaser and should that fail, a time sert kit, but I don’t know the thread pitch of the exhaust stud.  Could anyone help me with, and moving forward is there a way to obtain this information on my own?  Thank y’all very much in advance.

It should be the M6x1 (1mm thread pitch). ACE Hardware has taps that size, which will also work.

[CT]

Awesome, thank ya very much.  That works out, because from what I can tell some of my other questionable bolt holes are also M6x1.0, so one time sert kit should cover me for multiple applications should it come down to it. Thank you again.

[bryanj]

Timeserts are expensive and need a lot of metal arround the original hole for the 10mm tap.
Helicoils are cheaper and only use a 7mm(ish) tap

[PeWe]

Time serts are not cheap, but some threads need them.
Especially those that will be tightened and loosened a few times. (Or thin goods for helicoil, an insert can be longer.)
Like all engine covers.

My std M6 Time-serts from Wurth has the same tap as helicoils or at least very close. Thin insert, black steel easy to file if not seated all the way down.
- Insert OD 7.1mm, drill 6.2mm before its tap.

I removed an old bad helicoil from one head, inserted a time-sert in it since threads looked OK, no new tap nor drilling. Loctite 272 helps to keep it in place.

Big-sert is bigger and next step when the first insert is destroyed.
- OD 8.1mm, drill ca 7.2mm

Next the self tapping M6 versions,
- OD 9.0mm insert,  8.2-8.6 mm hole.
- OD 10mm  insert, 8.7-9.4mm hole

I have them all

I ordered real Wurth self tapping 9.0mm inserts.
Later bigger batch from China for a much lower price. Exactly same size.

Perfect for the cam holder bolts with lots of alu around in CB750 head.