Taper Piston Rings

[Gromit]

Hi Guys

I think this one has been discussed before .....

I do know that Nortons have taper piston rings specifically in the second groove to remove a lot of the oil ... put them in the wrong way up and hey presto they pump it into the combustion chamber.
Managed to get them right on my 650SS as they had TOP cunningly marked on them.

BUT !!

Do Triumphs have them too ??

My 750 T140 Bonnie has had a rebore, new pistons, valve guides and valves and now oils up the right plug in 50 miles left is oily but not too bad.

Now I am wondering as there was no etched TOP on these rings so how do I know which is the right way up?
Thought about holding them edgeways on a flat surface against a square to see which way they lean ... a parallel ring will stand upright but not a tapered one ..

Anyone know for sure if they are likely to be tapered ... btw I got the rings separate from the pistons so yes it is my fault !!

Regards Gromit 

[rogerwilko]

They would have been marked if tapered. Sounds like you haven't run it in correctly or broken a ring. The smoke won't go away In my experience.Get it rehoned with a coarser crosshatch. You've probably glazed the bore from overheating. When you first start the bike have it ready to blast up the road and load up the rings to expand them out to cut into the crosshatch. Just starting a rebuilt engine in your shed and letting idle for minutes on end doesn;t help the process.Before you do all this make sure it simply hasn't wetsumped.

[Welsh Wizard]

first what oversize did you go to?
Did you mic the bores after they had been rebored
did you check piston rings for clearance
 on standard (rings should be maked top manual warns
check that the compression rings are fitted the right way up ))
compression rings (tapered)   
width…………………….  .121" / .113"
thickness…………………  .0625" / .0165"
Fitted gap ……………….   .008 /  .013"
clearance in groove ……..    .0035" /  .0015"

Oil control ring
thickness ………………... .125"
width …………………....  .121"
fitted gap ………………..   .010" / .040"
clearance in groove ……..     .0015" / .0025"

[Gromit]

Cheers guys .... first the answer to all the observations is yes did that no one bore is ok the other is awfully oily yes yes 40 thou over and yes.

And I think you have answered my question which was are they tapered and the manual hints they are ... time for some spanner wielding ... again ... bloody thing

Regards Gromit

[L.A.B.]

Anyone know for sure if they are likely to be tapered ... btw I got the rings separate from the pistons so yes it is my fault !!

There are "piston rings", and there are "piston rings" so what type are they?

The last set of Hepolite/AE/Federal Mogul Triumph upper (1st & 2nd) piston rings I fitted were certainly marked "TOP".

[Gromit]

MMM came from a reputable dealer but I think a set form an engine machinist I use in Hepolite packing is called for.

Cheers Gromit

[Welsh Wizard]

Watch out, some Pattern rings as they are only tapered on the top ring only ( cheaper to make) top and the middle being tapered are called for by Triumph. so some times if you are not carefull with cheaper set you can end up with one piston with two tapered rings and the other with none, these being the middle rings of the cheaper set.

[Gromit]

Cheers WW
I have a vague suspicion from the problem that is exactly what I will find .... Hepolite for me in future !!

Gromit & Welsh Wizard recommend Hepolite piston rings to the Empire !!

Regards Gromit.