stripped exhaust port threads - Page 2 - Triumph Forum: Triumph Rat Motorcycle Forums
» Main Menu

Discussion Forums
 » Twins
 » Tiger
 » General
 » RAT

Features
 » Blogs

Motorcycle.com Links

Contribute
 » Photo

Motorcycle Forums
» Insurance
» Sponsors
» Our Partners
»ATV Reviews
»Motorcycle Games

Classic, Vintage & Veteran For Coventry and Meriden Models. Anything pre-Hinckley goes.

Reply
 
LinkBack Thread Tools Display Modes
Old 07-19-2012, 12:52 PM   #11 (permalink)
Senior Member
Powerbike
Main Motorcycle: '74 T140V Chop
 
Join Date: Jul 2012
Location: Woodbridge, UK
Posts: 388
Also, it's worth noting that if you are doing a shrink fit type, heat the entire head uniformly. Best to do it in the oven, as previously stated.

If you heat cast up on one side it CAN crack.

Freezing the insert will shrink it so it goes in a lot easier, too. If you do this then I would personally put the whole lot back in the oven afterwards to let it cool down slowly and uniformly. This just reduces the likelihood of cracking, once again.

Probably don't need to do the above but I find it's better to be safe than sorry
loxx101 is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 12-12-2012, 06:20 PM   #12 (permalink)
Senior Member
Team Owner
Main Motorcycle: The one between my legs
 
Snakeoil's Avatar
 
Join Date: Feb 2009
Location: Upstate NY
Posts: 5,987
Other Motorcycle: A few
Extra Motorcycle: Yes
I'm replying to this thread at this time because I am now addressing the loose spigot I have on the left jug of my '66 T120R. Today I picked up a replacement spigot and it screws in nicely. But it does not bottom out in the head and I suspect this is why the spigot that was in there was loose. Fortunately, it did not destroy the threads in the head.

I did a search here because I remembered this topic and Mr. Pete always driving home the point that the spigot MUST bottom out in the head in several threads on the subject of exhausts.

When I thought I could make an aluminum shim from 1/16" aluminum plate. It's not an easy machining exercise and because the actual port is not centered in the threaded spigot port, the shim either has to be offset or very thin. I managed to make it, but when I looked at it, decided it was a poor fix. So I will be machining back the threads on the spigot so it bottoms out and if necessary relieving the threads at the front of the spigot as well.

You have to wonder why they don't make the replacement spigots a bit longer and relieve the threads at the internal portion right off the bat.

I just wanted to thank Mr. Pete for sharing this important tidbit of info here. Otherwise I think I would have just tightened up the new spigot and move on.

regards,
Rob
Snakeoil is offline   Reply With Quote Quick reply to this message
Old 12-12-2012, 08:20 PM   #13 (permalink)
Senior Member
World SuperBike
Main Motorcycle: 1970 Bonneville
 
Join Date: Jun 2009
Location: Dearborn, Michigan
Posts: 2,145
Rob,

After wrestling the pipes off my '70 - which took three days - had to cut the cross over tube, I found the spigots to be pretty badly rusted with large flakes of corrosion coming off. I thought that new spigots were in order and contacted TMS in Nottingham for a pair. When they came they had the last two threads machined off just like the originals and just how the Triumph sages recommend. The chamfer (sp?) on the exit side was a bit not concentric but, oh well, how much can that hurt.

My point is that the last two threads need to be removed and of course the spigots need to be long enough to bottom out. Still don't really get the last two threads bit but will follow along on blind faith.

Regards,
Henry
henryanthony is offline   Reply With Quote Quick reply to this message
Old 12-12-2012, 10:06 PM   #14 (permalink)
Senior Member
Team Owner
Main Motorcycle: The one between my legs
 
Snakeoil's Avatar
 
Join Date: Feb 2009
Location: Upstate NY
Posts: 5,987
Other Motorcycle: A few
Extra Motorcycle: Yes
Henry,

The last two threads or in some cases more have to be removed because it is not possible to thread the port all the way to the bottom with a complete thread. So by removing the first couple of threads it allows the spigot to be screwed in without the threads bottoming out where the internal thread stops and this lets the end bottom out at the base of the port.

The new spigot I bought today has maybe 1 thread machined off the end. After inspecting the threads in my port, it looks like I'll have to machine 3 threads from the spigot. I'll measure it up tomorrow to be sure before I chuck up the spigot in the lathe. Guess I should take some pictures for the resto thread so this is clear to everyone asking about this in the future.

By the way, I thought about the requirement to bottom out the spigot in the ports. I'd never given it much thought before and figured it was to prevent hot gasses from impinging on the threads and possibly erode the threads from behind. But when Mr. Pete said it would beat out the threads, it all made sense. If you tighten it until it binds just on the end of the threads. It is fully supported only by the thread alignment and really only held tight by the last thread. If the exhaust is subject to vibes, it can, and based on Mr. Pete's comments, will eventually move the spigot side to side and once that happens it will continue until the threads are obliterated. But, if you bottom the face of the spigot on the bottom of the port, you now have a firm square base against which the spigot is held tight by the entire length of threads. Plus, all the threads are loaded against the flank of their back side. This puts both opposing lateral forces and compressive force on the spigot by the port. So, the ability to loosen the spigot and cause the spigot to move side to side is greatly reduced and apparently totally eliminated. Since I have one bottomed spigot that is rock solid in the head and the other bottomed on the threads only and was found to be loose, I've got real life proof right in front of me.

regards,
Rob

Last edited by Snakeoil; 12-12-2012 at 10:22 PM.
Snakeoil is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Triumph Forum: Triumph Rat Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter your valid email address, that can receive an automated confirmation message. Otherwise, you won't be able to gain full access.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Stripped Threads WDT3 Sprint Forum 12 10-16-2010 08:07 AM
stripped threads HOPOIL Classic, Vintage & Veteran 6 06-07-2009 12:51 PM
Stripped Threads MotT3 T3 Sport / Touring Forum 3 02-11-2008 01:55 PM
Stripped threads Colonel_Dorkus Twins Technical Talk 10 07-28-2007 08:55 AM
Stripped threads? Aggie98 Twins Talk 3 12-06-2005 04:54 PM

Powered by vBadvanced CMPS v3.2.2

All times are GMT -4. The time now is 10:28 AM.



Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Motorcycle News, Videos and Reviews
Honda Grom Forum Harley Davidson Forum Honda 600RR Kawasaki Forum Yamaha R6 Forum Yamaha FZ-09 Forum
1199 Panigale Forum Roadglide Forum Honda CBR1000 Forum Vulcan Forum Yamaha R1 Forum Yamaha R3 Forum
Ducati Monster Forum Harley Forums Honda CBR250R Forum ZX10R Forum Star Raider Forum Yamaha Viking Forum
Suzuki GSXR Forum V-Rod Forums Honda Shadow Forum Kawasaki Motorcycle Forum Star Warrior Forum KTM Duke 390 Forum
SV650 Forum BMW S1000RR Forum Honda Fury Forum Kawasaki Versys Forum Drag Racing Forum Ducati 899 Panigale Forum
Suzuki V-Strom BMW K1600 Triumph Forum Victory Forums Sportbikes BMW NineT Forum
Volusia Forum BMW F800 Forum Triumph 675 Forum MV Agusta Forum HD Street Forum Suzuki GW250 Forum
Yamaha Motorcycles Victory Gunner Forum Honda Vultus Forum HD LiveWire Forum Ninja H2 Forum Ducati Scrambler Forum

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.