off with its head or not?

[Jonesy :-)]

nah it was the other xs with straight thru 4-1

[excess.11]

With the original pipes on...I m surprised those remnants made it all the way out the exhaust and did nt just get battered around inside the baffles.

[Jonesy :-)]

And finally, when I started up with rag over muffler I caught these last few specks.
Shes all good Geoff, the aluminium alloy swarf is heaps softer than rings and bore.
there was no notable power loss or plumes of smoke following me on the ride so I reckon I got away with no damage.

[steptoe]

I,m nervous just thinking about doing this job,
I,m fairly certain I,d be a head off man, my luck a small, {no make that minuscule} piece would get stuck above the top ring and edge of the bore and be game over,
 good ideas on cleaning up, but mmmmmmmmmm nah 

[Jonesy :-)]

Good idea Jeff, but the head of the inspection camera is too big to fit in the plug hole. Good tip with the loctite and anti seaze Lou.

[excess.11]

Aldi recently have sold inspection cameras. Would have been an ideal tool for checking the bore for remnants after tapping.

[beemeerr11]

The previous owner of my bike had number 2 plug redone, I didn't know this until I went to replace the plug for the second time and the whole thread came out with the plug, I ended up using loctite No.272 (very high temp) and antisieze on the plug, the thread is now permanent and the plug will remove without the insert attached to it.

Cheers

[excess.11]

The tap you used is great for centering...but as you said...protudes into the bore whilst completing the lower section of threading.
I went at it with a starter.....intermediate then bottom tap .

[XSIIE]

Paul,

I hope NOT to faunicate the job as it is the head on my Ironbark,  The one which has a had couple of extras added. and many many hours of porting and polishing.

[Jonesy :-)]

Jeff
It was your VW job that swayed me or at least 2nd'd what I wanted to do, but with a variation to the greasy tap.
Scarfey
good thought, but the tap will actually foul on the open exhaust valve if you use a tap like I did (in the picture) If you used a tap that didnt have the "first stage" thread section so your "2nd stage" ended flush with the end of thread it might be a viable option.
Eddy
If it doesnt work and we damage our cylinders we might be able to get a bulk deal on repair parts  but I reckon if you take your time and be careful she'll be all good

oh and be careful you dont use a too long insert otherwise youll end up with a few threads protruding into the cylinder and have to remove and start again (dont ask me how I know) I used an insert with 9 turns in the end. The thread on my head had 14 turns and my F. up 1st go also had 14 turns insert but somehow I over wound it and had a couple of threads hanging past flush with end of plug thread. Some head scratching and time was wasted getting it back out

[XSIIE]

Paul,

I like the look of your tried and tested insitu engineering fix.

it's "on with its head" for me too

Eddy

[excess.11]

Like any of theae methods.....time will tell. The method i used was to dip the tap in bearing grease ....then rotate it in a cloth between your fingers to remove the excess ....so it only remains in the valleys. When tapping ....only a quarter to a half turn at a time....then remove and clean.
40 yrs later....vw is still chuggin along.
Bottom line is.....its your bike and your motor ....so do what your most comfortable with...because you have to live with that decision.

[SCARFEY]

Would taking the header pipe off, make an adapter to squirt air in while the exhaust valve is open blow any swarf back out the plug hole as it's being tapped work as a method

[Jonesy :-)]

Decided to go with the head on approach.
No greasing of the tap, so that swarf stayed dry and easier to vacuum out. Grease would have stuck the swarf to where it fell.
Did it with piston set on compression stroke so tap didnt foul with the open valves (this will happen) and almost all the way to TDC so the tap doesnt touch the piston. The theory also with near to TDC was so swarf wouldnt fall too far and make a neat little easy to vaccuum pile on middle of piston. (hopefully) After initial vaccuum piston was lowered to BDC to get access to the corner between piston and cylinder wall. Finally a squirt of compressed air with vac hovering over spark plug hole to gather remnant swarf.

I used a filter in the vac line to capture and see how much swarf I'd picked up to compare with swarf created with previously mentioned test run.

The reclaimed swarf and filter material


and vaccuum nozzle with in line filter


Another way I convinced myself it was ok to do with the head on was the fact that the swarf material is a lot softer than the cylinder walls and piston rings so hopefully if any remained it wouldnt score the cylinder.......thats my theory and I'm sticking to it

So Eddy what are you going to do?

[excess.11]

Drain the fluids......invert the bike .....tap away.....bob s ya uncle...
I recall doing a helicoil on a VW engine.....stuffed a rag in the bore thru the plug hole ....tapped and helicoiled.....then used pointy nosed pliers to remove the rag and swarf .
Use plenty of bearing grease on the tap ......and regularly remove ....clean and regrease to catch and clean swarf.
Crank the engine without any plugs in to help blow out any other stray remnants.
 Did nt have an issue. But it s a risky job.