This would explain the discoloration of the gudgeon pins as they were exposed to more than the normal amount of heat this engine would develop.
The discolored pins would explain the early signs of seizure just under the oil rings of each piston. If I saw this without the pins being discolored I would look into seeing if the piston had the correct clearance. The piston was getting too big for the bore. This happens when the bore isn't big enough for the piston or the bore is proper, and excessive heat expands the piston more than normal.
The microscopic vertical grooves are more, than likely, from honing swarf that was not washed away after honing. The honing stones leave microscopic bits of stone embedded in the cylinder surface. These alone can cause these scratches and also ruin a set of rings.
The carbonized oil coating between the top and second ring is troublesome. It should look more like the surface between the 2nd ring and the oil control ring.
I dragged the picture showing the two pistons and their rings to my desktop and opened it in photoshop. I did this so that I could correct the color balance and contrast to get a better look at the rings. The picture is slightly out of focus and a pretty small resolution. But what I can see shows rings that are in a distressed condition.
The face of the rings should be smooth and polished. From what little I can see yours look black with striations similar to what you see on the piston.
On another note, the cylinder is glazed and doesn't look to me that it had a coarse enough finish.
If it was mine I would remove the carbon from the top of the piston.
Get another set of rings.
In a perfect World I would get another gudgeon pin, but that might be harder than you think.
Get a set of new circlips.
Have someone break the glaze on the bore with a 150-180 grit honing stone (NOT A BALL STONE!!!!). No metal needs to be removed. You just want to rough up the bore.
If you don't already have it get some Motorcycle oil: We would use 20/50 API SG JASO MA. And because you are in the UK where break-in oil is everywhere, a good 40 weight break-in oil (or 20/50 if available).
WASH THE CYLINDER IN HOT SOAPY WATER UNTIL, when you wipe a white, lint free, paper towel with some oil on it, untill it comes out as clean as it came off the roll.
Put oil on the thrust faces of the piston, assembly lube on the gudgeon pin and assemble top end.
Start engine, but DO NOT let it idle. Have helmet on. Start bike keeping rev's up (blipping 1500-2500), let warm for a minute or two, and take the bike up through the gears putting a moderate load on the engine.
Then ride normally - no LUGGING (increases chances of detonation) and no RACING.
Thanks John, Will follow this advice. Looked at rings, they are polished evenly all the way round, but someone else who looked pointed out(on one ring at least) that the polishing was at the top which he suggested meant the ring/rings were in the wrong way up!! which would cause oil to get past... When I assembled the bike there were no indicaters to what way up they should go (which I expected!!!) and they certainly were not cheapo rings!!!!The gaps by the way az are ok!! Have ordered a new set of rings and also some valves, bit of scoring on a couple of them and the tops are badly 'dished) There is a engine re-conditioning shop local who a couple of guys in the Triumph owners club recommended. Lot of experience with car and bike heads... Has a Serdi valve seat cutting machine. Thinking about getting him to 'clean up' the seats..not pitted but they look at little 'grooved' Also thinking it will at least save me spending hours trying to get at good seal!!? But also wondering seeing as I'm at this point whether to just have new guides fitted as well (just for peace of mind if nothing else!!!) Happy with the rings analysis but worried about the carbon build up on the backs of the inlet valves??? surely that is oil coming down the guides??? The fact that the bike had a hard life (poor maintenance,misuse? etc..)makes me think if poor oil wore other components will it have wore/damaged/scored the guides as well??? Any thoughts on any of that???
Hi, Have decided against having new guides, just going with the valves, rings etc... All things considered after john's advice on Triumph rockers running 'drier' than most bikes the problem must have been the rings.... One more issue I could do with help though. When stripping down, the rocker shafts were turning in the boxes.. Got the exhaust one out, but the inlet shaft is still in the box.... had to undo the oil feed pipe and remove box with shaft, nut and feed pipe still on. Any ideas on how to get it out???
An air wrench will turn the nut so fast the shaft doesn't have time to react. This solution will require an air wrench and a Whitworth/BS socket wrench. Not sure you have access to those.
However, this may expose an issue you didn't know you had. The shaft is actually 2 separate pieces that aren't ever supposed to come apart. If the shaft is spinning, then the cap may have come loose from the shaft. Be sure and check for that.
Thanks RF, got an air wrench at work and it has done the trick!! Trouble is those shafts are going to spin when I re-assemble yes?? What can be done??? I have measured the shaft diameter (where the rockers run)In the workshop manual spec's it says they should measure .4990" - .4995". mine are measuring .4985" and a little less in places. Doe's that mean they re-placing anyway??
John, have measured the valves. One is about a thou under but they look marked. Can't measure the guide bore, nothing to do it with. They are my main concern... with the wear everywhere else (mostly down to unchanged oil methinks??)could they be not so much worn as scored?? Guy who is going to re-cut valve seats reckons the guides are ok (he 'wiggled them!) said one was 'a little' loose!!?? and he is highly recommended and no doubt has plenty of experience. Please forgive my paranoia on this issue, just want to dot the i's and cross the t's before re-assemmbly.. But just out of curiousity... what sort of life/mileage should you get out of the guides??? many thanks for the help...
Ahhhh, sorry guys...this is all a bit new and alien to me.. and I've had a whole lot of non-bike related crap to deal with this year... will try and keep you informed and keep everything together... glad you are still following the 'saga/nightmare!!!!
hi, had my mates t140v firing on 1 cylinder befor and after engine rebuild,checked everything still nothing, came across your post and took off live to switch and connected it to live on battery, now running perfect, new switch on order, thanks for your post saved my mate money and me a lot of time.
Re: T140 STILL.....Won't run right!!!!!
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