Exhaust thread knackered (or not?)

Smudge

Smudge

Active member
UKGSer Subscriber
Joined
Aug 21, 2007
Messages
387
Reaction score
8
Location
Kent
1989 R100 GS .... I have been aware of the offside exhaust thread problem for several years, and it hasn't given me any problems, but, I know it aint right so its bugging me. Having had a closer look today i am wondering if running a die down the threads would suffice, (plus a new finned nut). I can get the nut finger tight, plus a little bit with the spanner as it is now and to be fair it hasn't moved in 2 years. Is it worth giving it a try?
Also ... anyone got a exhaust y piece they no longer want, my collector box is on its last legs :(
Any advice appreciated(y) thumbnail_IMG_5304.jpgthumbnail_IMG_5307.jpg
 
If you can find a die to fit that it won’t be cheap. Not sure what pitch the thread is as haven’t taken mine off yet.


Sent from my iPhone using Tapatalk
 
Thanks for your replies … I’ve never used a thread file, but I will give it a look.
Regarding the die, if it is worth saving , my next question would be, what size? 😜
 
Get a thread gauge and a vernier and measure it. Try Grasam Samson for a die once you know the size.


Sent from my iPhone using Tapatalk
 
Problem with that thread is,it’s already had a fair bit of material ripped off and looks to be tapered.
Running a die down it will only remove more metal( or a thread file for that matter.)
If the existing nut is tightening up you could leave well alone.
Regardless,I’d get it sorted properly anyway.
It’s a 10 minute job to pull the head / barrel off .
And a couple of hours to prep and refit.
No brainer.
 
I’ve always backed the exhaust rings off a bit every few months. I suspect a lot of the evident damage on yours is as a result of thread galling.

I’d be interested to know how it can be repaired properly.
 
ChasF said:
I’ve always backed the exhaust rings off a bit every few months. I suspect a lot of the evident damage on yours is as a result of thread galling.

I’d be interested to know how it can be repaired properly.
Click to expand...
By giving it to the Wizard of Mikeyboy, he will perform arcane magikery and return it fetalized and good as new ;)
 
Mikeyboy is right, I'll get it sorted properly, then it wont be a worry anymore. I am removing the nearside head anyway, push rod oil seals weeping, so i may as well do both, and give them a good fettle while I'm in there (y)
Next job, wip 'em off, check the valves are doing everything they should do, then go from there ... thanks for your input everybody ;)
 
mikeyboy said:
If the existing nut is tightening up you could leave well alone.
Click to expand...
Perhaps a New Nut might be a good investment, BUT If you can screw the existing one on by hand and nip it up with a spanner and it does not leak?

It is what is known in the business as serviceable !! and probably best left alone, to be honest !

Mind you 20 odd years ago I had the threads done on my R80 heads with brass outer sleeves what a difference that made and I still see the bike about It was here a couple of years ago for some tweaks and they screw off so easy with just a tap on the spanner BUT I think it was £100 on an offer from Motorworks Lord knows what it would be now!!

Oh and only apply the smallest portion of Alloy Anti seize not coppaslip when refitting
 
Last edited:
thanks mate … I keep looking at it and change my mind every time I walk away 😂😂😂
 
ChasF said:
I’ve always backed the exhaust rings off a bit every few months. I suspect a lot of the evident damage on yours is as a result of thread galling.

I’d be interested to know how it can be repaired properly.
Click to expand...

I used to send heads to BLR engineering, but that was a long time ago.
They used to fit phosphor bronze exhaust threads ..one of my own airheads has them fitted :D

Here’s a similar thread from 2022

Paradiso

Thread 'Exhaust thread reconditioning'

Hi. Can anyone recommend an engineer to sleeve or weld and recut an airhead exhaust thread? I did a search, but couldn't find any recent names/services. It's an R65LS, 1983. I'm in the North East/Teesside area. Thanks.

Sent from my SM-G925F using Tapatalk
 
Last edited:
Don't think a Die will work, the thread looks like it may also be tapered (maybe just the photo) if parallel it will be a very expensive Die.
I'd take the head off and take a few measurements OD and pitch with vernier calipers. Buy a good quality thread file (or borrow one) and a set of thread profile gauges to check / confirm pitch and profile. Thread filing is not difficult, keep it moving round the circumference, de-grease and clean before starting but nothing whilst filing. Check frequently with thread profile gauge. I'd definitely buy a new finned nut, and again check this by hand on filed profile frequently for fit and clearance etc.
It will definitely be metric fine so 60deg V-form and likely 1.5mm or 2mm pitch?Screenshot_20250730_162725_Chrome.jpg

Good luck 👍
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
You must log in or register to reply here.

Similar threads

Smudge
Exhaust header pipes thread knackered
2
Replies
21
Views
3,516
Garry H
Garry H


Back
Top Bottom