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.