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Discussion Starter · #1 ·
Hi all, decided to delve into the engine of the T140 today and got a bit of a surprise at the condition. It’s a US import and was solid but tatty so was expecting a full engine rebuild but not sure now. Pistons are +060” by the reference number. Any ideas what I should check next ? Not sure how to proceed. Opinions invited.
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Left cylinder looks a bit rich, otherwise not bad at all.

You'll need to pull the cylinders off, taking care not to mix up the cam followers, they'll want to drop out as soon as you lift the jugs.

Pull the top ring from each (one at a time), take care to immediately mark the TOP of the ring, so you can replace it exactly how it was. GENTLY squeeze the ring JUST enough to push it carefully into it's proper bore with the upside-down piston until it bottoms out on the middle ring, then pull the piston out of the way and measure the end gap. Much more than .005" might produce carbon buildup and smoking. .045" is better.

I'm going to guess that you cleaned those piston crowns, they usually resemble their matched combustion chamber...
 

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Discussion Starter · #3 ·
Hi thanks for the reply. I haven’t cleaned them that’s what the surprise was. All the fasteners undid easily there was oul around the head and the pistons were gleaming. I presume someone has given it the once over recently. But I’ll check the bores like you said. Is there anyway to check the bottom end without splitting the cases.
 

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Is there anyway to check the bottom end without splitting the cases.
You can get a prey fair idea with a large bench vice with jaw protectors, and a dial indicator.

Clamp the engine in the vice and check the crank for runout (dial indicates movement when you try to force the crank up, down, or side-to-side)

Check the connecting rods for minimal "flop" (they are supposed to have limited side-to-slide play on their journals, and shouldn't "tip" at the little ends. You need to somehow carefully LIGHTLY wedge a thin screwdriver between the rod and the crank cheek (don't press or force it, find a thinner screwdriver or use a stack of feeler gages), then set your dial indicator (at the top of the rod) on the same side as the wedge and gently press the top of the rod toward it. I don't know the spec offhand, but should BARELY be perceptible if ANY
 

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Discussion Starter · #5 ·
Yes I’ll get the DTI out. Not sure my vice is big enough to hold the engine but I may be able to screw it to the bench. Im going to take the side covers off check the clutch oil pump etc. is there anything specifically to check or is it just common sense checks.
 

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Discussion Starter · #9 ·
Mmm I was hoping to avoid splitting the cases but maybe that was wishful thinking as I don’t have any history on the bike.
 

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Mmm I was hoping to avoid splitting the cases but maybe that was wishful thinking as I don’t have any history on the bike.
This was my sludge trap....
Engine was clean, crank on standard bearings and bores +40 thou. Can't be entirely sure of the mileage, but it is not excessive. The bike has sat in a shed for thirty years.
Whilst in there you could also check that you have the later type timing side main bearing.
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Discussion Starter · #11 ·
That’s pretty full of crud. I’ll have to give it the full strip. Did the crank need regrinding and would new Conrad’s be needed. I’ll replace the bearings while I’m there.
 

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An unknown engine out of the bike..You might as well take it right down at this point. Be wary that you may like to leave some parts alone if they are in perfect condition. New parts may be inferior quality, but do look in that sludge trap.
 

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Yazwaz, If you have the engine out of the frame, it only makes sense to do a tear down and inspect everything that could be worn. The sludge trap is worth taking a look at...it'll be good for your piece of mind knowing that you have inspected and cleaned it out. The head looks to be in pretty good shape, and with the cylinder barrel being on the last oversize, it makes me think the bottom end has also been done at some point. Could be a pretty simple overhaul. Best of luck with the results.
-Dave
 

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Hi Yazwaz, A few thoughts.

Did you ride bike before tear down? If yes, how far? Did is use oil?

The top end looks pretty good. You won't see rings & piston sides until you remove cylinder.

The only way to know if bottom end is good is full tear down. You can measure bearing play perfect, yet have rust from more recent storage etc. Sludge trap, you won't know. If plug is not original or shows not original punch mark you know plug was at least removed. But how is trap.

If you have any concerns at all about bottom end you must do full teardown. If the big ends look perfect, the mains look perfect, reuse them. Be sure to test & give oil pump a full visual inspection.

This will give you chance to inspect transmission parts as well.

If bores look good. Did not use oil before tear down do nothing with bore or rings. Just clean them with carb spray & blow them off. Don't hone cyl don't remove rings. Just oil well & put cyl back on. The used rings will find their old spot in just several miles. I've done this many times. If I've removed rings & put back on some start burning oil. I can't say why.

Or hone & ring if that is best way to go. Even with light rust ring in bores I've seen 2 motors run many thousands of miles. Like 20+ k miles. Motor was taken apart for other reasons, not oil burning.

Thing is, you have the motor out now. Of course it's lots of work to fully strip motor. But if you strip it now, replace worn/defective parts, you'll be done with it for many years & thousands of miles to come. Do it right your looking at a good 30-40k miles of trouble free service. So long as you don't sell bike you'll ride every penny out of the job. Done right these bikes are very reliable & trouble free.
Don
 

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Hi Yazwaz,
With any British bike there is a long history, if you are very lucky the last person to rebuild the engine will have been someone with great experience and skill, who took great care in their work; unfortunately you might find a that they were not.
I always split the cases on a new to me Triumph, then I know with certainty who the last idiot who had their grubby hands in there was. If there are subsequent problems I know who to blame. The trouble is that the more you look the more you can find and the more it costs in the short term.
The sludge trap appears to have no logic, sometimes they are 10% full and sometimes they are like this, it’s a dilemma that can only be resolved by looking and sometimes you save the engine:
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As a minimum I change the bearings, especially the weak timing side ball bearing for the late type special roller.
The big end shells, I change for Vandervell NOS tri metal, sometimes you need polish and sometimes a grind on the big end. You will need big end cap bolts and crank oil feed seal.

I would always get the crankshaft rods and pistons dynamically balanced.
Careful static balance and weight matching can prove to reduce vibration greatly.
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However, costs do add up rapidly and the gearbox and primary drive and oil pump have not been mentioned yet.

Not looking does not mean there are no problems inside the crankcase, if there are any weaknesses then they tend to manifest themselves catastrophically if not resolved.

Sometimes you can get away with little expense, sometimes it’s a money pit.

I would recommend stripdown cleaning, measuring and inspecting, then decide what is good to go and what needs replacement or refurbishment.
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Your engine as it stands:
The valves do not look excessively pocketed, the guides will need inspection, the dark combustion chamber worries me in case it is oil burning deposit.
The piston and ring condition can only be determined after pulling off the barrels, if they are already +60, you have no rebores left on that barrel.
The head studs are the wrong way up and need turning over.
The strange surface finish of the piston crowns is worrying, I suspect that is the product of detonation pockmarking the pistons. If this is the case then this needs to be resolved.

good luck
Peg.
 

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That’s pretty full of crud. I’ll have to give it the full strip. Did the crank need regrinding and would new Conrad’s be needed. I’ll replace the bearings while I’m there.
Bearings were measured as spot on. No bent conrods.
I am taking the opportunity to change bearings in engine and gearbox. Also had bores honed and am fitting new rings.
There's a lot of info on here about main bearing types and clearances. Well worth researching this before rebuilding.
 

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Discussion Starter · #17 ·
Thanks for all the input guys. I didn’t ride the bike before strip down and it only ran briefly due to carbs etc. so for piece of mind I’m going to do a full strip down. I’ll be seeking advice as I go along so be prepared for more questions.
 

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Discussion Starter · #18 ·
Well took the barrels off this morning and not good. It’s already on +060” and the left pot has some bad scoring in it.
 

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New cylinders or re-sleeve then. Plenty out there in the UK now
 

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I always split the cases on a new to me Triumph, then I know with certainty who the last idiot who had their grubby hands in there was. If there are subsequent problems I know who to blame. The trouble is that the more you look the more you can find and the more it costs in the short term.
The sludge trap appears to have no logic, sometimes they are 10% full and sometimes they are like this, it’s a dilemma that can only be resolved by looking and sometimes you save the engine:
View attachment 774199

I would recommend stripdown cleaning, measuring and inspecting, then decide what is good to go and what needs replacement or refurbishment.
Great advice, Peg.

As to why the grunt in sludge traps vary wildy between similar bikes? IT'S ALL DOWN TO REGULAR OIL CHANGES and maintenance. Other factors do play in, such as air filters, whether the bike was ridden moderately or THRASED regularly, etc.
 
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