Smokey T140 after rebuild. Need Advice please. - Triumph Forum: Triumph Rat Motorcycle Forums
Classic, Vintage & Veteran For Coventry and Meriden Models. Anything pre-Hinckley goes.

 9Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 24 (permalink) Old 05-19-2019, 09:27 AM Thread Starter
Grand Prix 125
Main Motorcycle: TBC!
New Member
 
Boggie's Avatar
 
Join Date: May 2019
Location: West of London, UK
Posts: 27
Smokey T140 after rebuild. Need Advice please.

Hi*all,

I have been looking at buying a T140 for a while and just been to*see a lovely restored bike. The top end has been rebuilt with barrels rebored, oversized pistons and new rings. It is not yet run in, in fact it has not been on the road since the engine was put back together a couple of days ago.

The bike started easily and the engine sounded great but was rather oil smokey on start up, more so on one side and this did not clear as the engine warmed up. In fact it got a bit worse. Would that be normal for a brand new rebuild or could something else, such as valve guides be an issue? If so, is this a*big job?

Many thanks,
Ian
Boggie is offline  
Sponsored Links
Advertisement
 
post #2 of 24 (permalink) Old 05-19-2019, 09:45 AM
Site Supporter
Commentator
Main Motorcycle: T140 E
Lifetime Premium
 
Join Date: Jun 2009
Location: Reading Berks UK
Posts: 9,248
Other Motorcycle: 56 Plunger Tatty Cub
Extra Motorcycle: CZ winter bike
Starting a fresh engine isn't too clever if it isn't ridden as part of the process
It could well just be oil left over from assembly
DAVE M is online now  
post #3 of 24 (permalink) Old 05-19-2019, 10:06 AM Thread Starter
Grand Prix 125
Main Motorcycle: TBC!
New Member
 
Boggie's Avatar
 
Join Date: May 2019
Location: West of London, UK
Posts: 27
Hi Dave, thanks for the reply. He started it and ran it for about 5 minutes so I would have thought that would mean any assembly oils etc would burn off. But I might well be wrong.

Assuming this is not the issue, what are the next likely issues please? I was thinking maybe valve guides?
Boggie is offline  
 
post #4 of 24 (permalink) Old 05-19-2019, 10:17 AM
Team Owner
Main Motorcycle: T160
Moderator
 
Join Date: Oct 2011
Location: Great Britain
Posts: 5,741
Other Motorcycle: T100, T150
Smile

Hi Ian,

Firstly, welcome to the Forum.

Please fill in at least a basic Location in your Forum User Profile, this'll appear automatically beside all your posts, helps responders if advice needs to be location-specific. Imho, this is one of those occasions ...

Quote:
Originally Posted by Boggie View Post
the engine sounded great but was rather oil smokey on start up,
Would that be normal for a brand new rebuild or could something else, such as valve guides be an issue? If so, is this a*big job?
Errrm ... if you don't know, depending on your location, this is probably not the bike for you.

There can be all sorts of reasons a Britbike smokes, none of 'em good. If, say, you're in GB, and you aren't limited to a particular version and/or year, T140 is not exactly a rare bike, you don't need to buy one with obvious problems. The only two exceptions I can think of are:-

. if the bike's being offered at such a low price you've enough money left - and you don't mind learning - to do all the alleged top end work over again;

. your location is so remote (Australian Outback?), T140's - smoking or not - aren't very thick on the ground ...?

Ime, to avoid disappointment, it's wise to treat any seller of a forty-plus-year-old vehicle you don't know as a complete idiot; if you find out subsequently he/she had some mechanical ability, it's a pleasant bonus.

Hth.

Regards,
HayMike likes this.

Stuart
StuartMac is online now  
post #5 of 24 (permalink) Old 05-19-2019, 10:39 AM
SuperSport
Main Motorcycle: 70 BSA A65
Senior Member
 
Join Date: Jul 2014
Location: Mississauga
Posts: 1,190
New rebuilt should be run in without too much idling for the first start - what seller does ( trying to sell a bike which is not run in properly and trying to move a problem to buyer ) is wrong. He is also not doing engine any favors running it in the garage without load.
Adam M. is offline  
post #6 of 24 (permalink) Old 05-19-2019, 01:47 PM Thread Starter
Grand Prix 125
Main Motorcycle: TBC!
New Member
 
Boggie's Avatar
 
Join Date: May 2019
Location: West of London, UK
Posts: 27
Been researching and chatting to a mechanic friend:

As a general rule; smoke on acceleration is usually rings, smoke on deceleration is usually guides.

When the engine accelerates, manifold vacuum is low and so any smoke could caused by oil passing the scraper ring, into the chamber and burning. Oil consumption will be very high and plugs will be very oily. When the engine decelerates, manifold vacuum is high, and oil can be drawn via the valve guides, into the chamber and burn with copious amounts of smoke at idle and immediately after taking off from a standstill. Oil consumption will be up and plugs will have some oily black deposits.

Typically, oil passing the rings will be continuous under all running conditions but more so under acceleration / revving up. It's quite possible that she is getting oil from both rings and guides. This bike is creating smoke under both conditions but more on acceleration (revving up) and more so on one side than the other so probably not an issue common to both cylinders.

Note: A little smoke at start up is normal and caused by oil from the cylinder head (as a little oil drains from the guides while sitting after being out for a run). However, this is at idle and for a period after starting, usually clearing after a short period of time. As this bike did not clear then I don’t think this is the issue.

Here are some more details:

Piston rings
Broken oil control rings would cause the issues but this is unlikely as they are new.
As the top end had been rebuilt recently, it might be worth checking the ring gaps. Should be around .010" for the compression and scraper rings. Too big gaps and oil can get through. This could be the problem here but probably not.

Valve Guides
Guides can crack and this could be the problem but probably not.
Worn guides are becoming more common. They used to last forever but modern unleaded fuel needs additives to help lubricate the guides. This could be the problem.

Oil where it shouldn’t be
Leaks around the head gasket - have the head bolts been re-torqued after heat-cycling the engine? This is where I would check first as the engine has just been rebuilt so could be the issue.
Check to make sure the oil in the rocker boxes is draining properly.
Blocked engine breather – excessive pressure in the engine could be forcing oil up the bores.
Wet sumping – too much oil in the sump being splashed up by the crank and con rods. However, this should be about the same on both cylinders if you are on the main stand so probably not the problem.
Oil pressure relief valve spring within spec? A short spring will allow too much oil in the sump but again, I don’t think this is the problem as the smoke was more on one side.

Bottom line
The issue is probably easy to fix, however the costs will be in identifying what needs to be done. I could be looking at quite a large labour bill to find the fix. If the valve guides are cracked or worn, there will be a cost for either a replacement head or some machine shop work to replace them. Best case scenario is that a head bold re-torque fixes it at 1h labour. Worst case scenario is that after a lot of mechanic’s time the problem of valve guides is identified. The labour plus parts could be £500 - £1000.

Any other thoughts please? I really like this bike and it is a rare model too. I have negotiated a price with the dealer of potentially taking the bike as it is and taking the risk but it is only works out that the bike is around £400 cheaper. Should I take the risk? Apart from the smoking and a few minor things, this is a really nice restoration of a limited edition T140.

Cheers,
Ian
Boggie is offline  
post #7 of 24 (permalink) Old 05-19-2019, 03:00 PM
wol
Moto Grand Prix
Main Motorcycle: T140 "special"
Senior Member
 
Join Date: Oct 2010
Location: Carmarthen UK
Posts: 2,505
Other Motorcycle: 1970 T120R Project
Extra Motorcycle: yes please
would be interesting to know what year / model of "limited edition" T140 this is and what the price is

if this would be your first Triumph T140 you really need to take someone who knows these bikes with you to help with your decision to buy or to walk
----- there are lots of T140s out there - none of them really rare --
better to get the guy to fix the smoking and pay the full amount - if he will not do that you have to ask Why?

you have already answered the cost question yourself - to fix an unknown top end problem - cost reduction should be around £1K (and thats if its not overpriced to begin with)
wol is online now  
post #8 of 24 (permalink) Old 05-19-2019, 03:09 PM Thread Starter
Grand Prix 125
Main Motorcycle: TBC!
New Member
 
Boggie's Avatar
 
Join Date: May 2019
Location: West of London, UK
Posts: 27
Hi Wol, it is a fully restored UK Jubilee edition. One of only 1000 made back in 1977.
Boggie is offline  
post #9 of 24 (permalink) Old 05-19-2019, 03:18 PM
Site Supporter
Commentator
Main Motorcycle: T140 E
Lifetime Premium
 
Join Date: Jun 2009
Location: Reading Berks UK
Posts: 9,248
Other Motorcycle: 56 Plunger Tatty Cub
Extra Motorcycle: CZ winter bike
Be aware that they made more than 1000.
I don't like them so I am biased.
DAVE M is online now  
post #10 of 24 (permalink) Old 05-19-2019, 04:01 PM Thread Starter
Grand Prix 125
Main Motorcycle: TBC!
New Member
 
Boggie's Avatar
 
Join Date: May 2019
Location: West of London, UK
Posts: 27
Interesting. I read that there were 1000 UK spec bikes, 1000 US spec bikes and 500 for the commonwealth. Is this not the case?
Boggie is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options
All posts must adhere to Forum Rules

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:
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:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Alternate front master cylinder and rebuild kit Rollinslow84 Hinckley Classic Triples 11 08-09-2017 11:58 AM
T140 frozen after rebuild BKD Classic, Vintage & Veteran 16 09-07-2015 01:41 PM
Advice on Front Suspension T140 Smoedog Classic, Vintage & Veteran 5 07-13-2015 12:01 PM
help and advice needed on 73 T140 Jan_73_Bonne Classic, Vintage & Veteran 1 08-20-2009 12:19 PM
Any advice for a possible future T140 owner? Greaser Classic, Vintage & Veteran 7 09-12-2004 09:55 PM

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

 
For the best viewing experience please update your browser to Google Chrome