Triumphrat

wolfwolf

Im working on a T140 project. It wasnt running when I got it but did have good compression. I tore the motor down because someone powdercoated the complete engine from the cases to the head.

My question is if I am going to reuse the pistons and rings, they look really good, should I hone the cylinder or just clean the glaze?

or should I hone and re-ring while its apart?

or pistons, rings and hone?

Im thinking a complete top end in a year or so will be needed, I just cleaned the valves and laped them and put the head back together, but I think new seats, guides and valves or in the near future.

opinions...

Truckedup

My opinion is if you are going to keep the bike then do the top end now.Yeah,just the top ends always becomes a lot more

Mr.Pete

If the rings and cylinders look "really good",you could re-use the rings without any honing.
If you've taken the rings off the pistons,you probably should replace them.

If there's less than 0.006" wear on the cylinders,use the old pistons with new rings.When you do a re-ring,you should hone the cylinders with a #180 grit hone (#150 - #220 will do).

wolfwolf

Thanks guys, Ive already replaced all the bearings, seals, ect. and money is getting tight, I havent taken the rings off the pistons yet, so I think Ill just clean the cylinders and save it for next winter.
This isnt my primary ride so it wont see alot of milage anyway.

BirdoPrey

I disagree with the idea of reusing the old rings. If the pistons are good and the bore is good reusing the pistons is fine and is in fact common. However, once the rings have seated then trying to reuse them is, in my opinion, a mistake and against normal shop practices.


So, I vote for hone and new rings.

But, it's your bike, and if you do reuse the old rings and it works out fine, repost and give us an update after a couple of thousand miles. Be interesting to hear the results.

Art.

Rookster

Why not measure the bores or get a shop to do it. It won't cost you much to bring the cylinder in and have it measured. I agree with Art that you should be using new rings at the least.

Consider this: Why put it back together now to only rebuild it again in 1 year. Do it right the first time and then you shouldn't have to pull it apart again for another 5 years when you will have to replace the pushrod tube seals

Scott

rambo

I have cleaned my bores using a rotary wire brush in an electric drill.Gives a great finish that looks like a rebore.My T120 burns virtually no oil at all after building it this way.I would re-use piston rings if they fit the bore with the correct gap and the piston grooves are not worn out

tommytiger

Wolf, I can only go on my personal experience.

My 78 Tiger was running well but smoking a little on the over run and compression was low.

The head required new guides, valves and and springs. When I measured the bores they were not oval or tapered but were on the limit of wear stated in the Triumph manual. The pistons were also on the limit of wear aswell, I feared a rebore and new pistons were needed but the advice I got on the forum was to Hone and fit new rings. I followed the advice and fitted L.F. Harris rings, the bike has run perfectly for 2000 miles now, no smoking at all so I'm really chuffed. You can hear the pistons slapping about in the bores when the motor in stone cold but it quietens down once warm.

It's a shame you didn't run the motor whilst it was together, I think you need to measure or get measured the bore and piston (at the skirt) if they are within tolerance I would hone and re ring.

loxx101

Why would you use a wire brush?! I see no reason to do that. It's simply not going to give the same finish.

Honing tools are cheap. Just do it right!

Mr.Pete

You can't take dimensions in the General Data of the Triumph manual as being wear limits;they aren't.
They are the dimensions a new part would measure at,before any wear occurs.

Most "new" clearances can wear to at least double,without creating any serious problem.