Undoing R80 exhaust pipe nuts ?

[Sibbo]

R80 exhaust nuts .... those beautifully cast little things that I don't want to break ..... are they easy to undo ? and what is the correct method ? Gentle tapping with a hammer and a block of wood ? Make up specific spanner to fit ?

and the reason I ask is that it's time for a set of rings on my ST. She doesn't really use a measurable amount of oil but after a few km of slow riding and handful gets a big cloud of smoke ... which then goes away on acceleration . She's pretty clean but smells a bit smokey and I'd prefer her to be a little more pristine . SO, rings , perhaps valve guides ?

But first a gentle look inside and take the heads and barrels off to the doctor .

[ME 109]

Rule number 1. Don't force them undone.

Rule No's 2 thru 9. Refer (reefer ) rule No.1

If they don't turn reasonably easily, or get harder and harder to turn, cut them off. No shit.
Cheaper to get new star nut than an expensive head repair.

If you need to operate, the bmw method of drilling holes and appropriate chisel is thew way.


Please, don't follow that !@#$@ BMW $#@@##$$ mechanic on you#@!@tube. We don't want no steenkin' dremel/chisel marks on the exhaust threads.

[Sibbo]

I just found him, he seems sure of himself in an objectionable kinda way .

I don't own a Dremmel anyway .

[Pattern14]

I've had this problem myself from time to time, and have had to fork out for expensive thread repairs. The correct tool is a BIG help, so is soaking the header pipe nuts in WD40 or such for a few days, then putting on a hair dryer/heat gun. Hot/cold, more penetrating oil, repeated until you develope a mental health condition, or the nut frees.Stripping the threads is a PITA, and I recall having a "Guru" many years back destroy my header pipe nuts with a cold chisel. If you have the patience, they will eventually come off. Alternatively, you can unbolt one head, and remove it with the header attached, as the balance pipe is normally a sleeve fit ( well, on my 1977/78 bikes it is), and then find a machine shop with a gentle handed tradesman to cut off the header nut without damaging the thread on the heads. Using anti seize when reassmbling is a must to avoid this problem. Done the same thing with seized fuel tap nuts, but on a smaller scale, and managed to salvage them. Hope this helps

[Sibbo]

Thanks, I think I might make myself a spanner to suit and buy a new can of WD40.

[SteveD]

Cut 'em off. I did mine with a new hack saw file down about 3-4mm (can't remember exactly) then cracked it with a chisel. It only took 5-10 minutes.
Anti-seize is a good thing for the next ones.
A dremel is ok as long as you know the exact depth to go before giving the new slot a chisel whack.
Years back before I had the correct tool, I just used a pipe wrench, but you risk bending one of the little flowerettes!

[Sibbo]

I'm going to try to get them off and hope the PO used the right grease ...copper based ? My exhaust is a wee bit complicated (2 into 1 with a mixing box ??)and I'd just love drop the rhing in one peice but I'll cut if I have too.

Shudder !

[PAS]

Thanks, I think I might make myself a spanner to suit and buy a new can of WD40.

Buy some proper penetrating fluid and not the "Water Displacing 40th attempt".

[bbelk]

These wrenches are pretty cheap an work really well.



Then after you get carried away - you can buy some of these:



They work really well too, but I wish I had sawed the nuts off.

[Duane Ausherman]

............ But first a gentle look inside and take the heads and barrels off to the doctor .

Sibbo, as always, start with Google. You will find http://w6rec.com/duane/bmw/exhaust/ among a couple of other articles that are useful. Go to images and you will see a variety of tools.

For others that are new to BMW motorcycles, buy them up ahead of time off of eBay. I have sold many exhaust nuts that I had glass blasted and were nearly perfect for only a few bucks each. They are cheap.