Photos of damages in T140 - Triumph Forum: Triumph Rat Motorcycle Forums

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post #1 of 52 (permalink) Old 01-02-2013, 07:58 PM Thread Starter
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Photos of damages in T140

The follow-up of this post : http://www.triumphrat.net/classic-vi...-new-year.html
Taking the rear rocker box out of a 76'T140 is just not easy. There must be a 32d of an inch to slide the whole thing out of the bike frame.
Anyhow, here we are. Bike sounded " not so funny " for two seconds and then rode home for 10 miles at low rpms. Sounded actually just fine in the garage at idle, if it wasn't for the smoke out of the crankcase breather. 160 lbs on right cylinder, 50 lbs on the left !!!
Here is what happened :
The top left compression ring was broken ( in insight, from the time I bought the darn bike 750 miles ago ). In my last ride, the pieces finally made it out through the piston top. That is when I heard the bad sound for 2 seconds...and then it was ok.
As I took the exhaust out, I could hear some loose metal pieces in it. They were pieces of that broken top ring.
Please see photos.
A good friend of mine who has worked on " vintages " bikes for a very long time told me it does happen, sometimes for no reasons, and in my case, the head was salvageable and the cylinders might need either new rings ( & 1 piston ) or new oversize pistons + rings and a rebore. But the crankshaft should be fine. The two lower rings were fine and the left cylinder bore does show a tiny bit of markings but can't be felt with the fingers at all.
Overall, it sounds as if it could have been much worse, and I might be fine.
A sub-contractor of my friend will check out the parts, redo the head and might if needed redo the bore.
What a day...after having to redo the CV shafts on one of our cars....and a broken door handle.






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post #2 of 52 (permalink) Old 01-02-2013, 08:42 PM
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wow, crunch! It does show how tough these bikes can be.
I know those tapper rings are brittle but I wouldn't expect them to break insitu. I hope they were not hepolite. I'd wonder about air/fuel mix and oil starvation when you get back.
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post #3 of 52 (permalink) Old 01-02-2013, 08:44 PM
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Protect those conrods from striking the sharp edge of the spigot opening and putting dings in them. I like to use foam pipe insulation to protect conrods in this type of situation.

regards,
Rob
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post #4 of 52 (permalink) Old 01-02-2013, 09:12 PM Thread Starter
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Originally Posted by DaveDone View Post
wow, crunch! It does show how tough these bikes can be.
I know those tapper rings are brittle but I wouldn't expect them to break insitu. I hope they were not hepolite. I'd wonder about air/fuel mix and oil starvation when you get back.
matter of fact : I can't read the piston tops but the under side says :
Hepolite 19162...413 !
What does it mean ?
Stock pistons ?
Standard size ?
please let me know
Terry
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post #5 of 52 (permalink) Old 01-02-2013, 09:40 PM
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Folks I know around here say the hepolite pistons and rings are the best.
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post #6 of 52 (permalink) Old 01-03-2013, 01:41 AM
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Your problem is detonation (pinging) or pre-ignition.

The fuel mixture may be weak, fuel octane rating too low for the compression ratio, timing too advanced, or even just bad riding, holding onto a high gear at low speed. Do you keep revs above 3000, on the open road?
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post #7 of 52 (permalink) Old 01-03-2013, 03:51 AM
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Very very lucky indeed Frogon. The top of that piston looks very close to coming off. I've seen that happen, leaving only a crank & head as salvageable !
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post #8 of 52 (permalink) Old 01-04-2013, 12:11 PM
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I'll bet the valves & seats need to be AT LEAST lapped to clean up damage from chewing on ring bits, may need re-grinding if they are gouged at all.


Still, you dodged a bullet!

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post #9 of 52 (permalink) Old 01-04-2013, 01:17 PM
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Quote:
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Your problem is detonation (pinging) or pre-ignition.
I shouldn't be so positive. I was just looking at the piston top in the 1st pic and what I thought were splatters from detonation may just be damage by the bits of ring.

Still don't like the "happens for no reason" explanation. Pre-ignition can eat through the top land and let the ring out.

What you really don't want is for it to happen again.
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post #10 of 52 (permalink) Old 01-05-2013, 03:23 AM
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Wouldn't surprise me if that piston had a busted ring right from day one.


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