Author Topic: ring gaps and piston  (Read 1005 times)

Offline spyke

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ring gaps and piston
« on: 12.01. 2011 22:08 »
Hi chaps,
Just got my barrells back from T and L, sleeved, bored , honed and cutouts enlarged . Just fitted the Hepolite pistons to rods , is there a particular way round (the valve cut outs are the same size)and nothing written on piston crowns.

Barry at T and L said i probably wouldnt need to check ring gaps cos Hepolite are reliable size wise ,unlike some other current options, but i just pushed a comp ring into the bore and gap is 11 thou , does  that seem about right?
Cheers Spyke
A10 spitfire style

Online Brian

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Re: ring gaps and piston
« Reply #1 on: 13.01. 2011 02:09 »
11 thou is fine Spyke. The book recommends .011" for the oil ring and .013" for the compression rings but a couple of thou wont matter.

You should always check the end gaps in the rings no matter what brand of ring. I had a case recently where I bought a set of +.020" pistons but they had std rings supplied with them.

If the pistons dont have any marks to indicate which way round they go (usually a arrow pointing forward) and the valve cutouts are the same on both sides and there is no other difference from either side of the piston then they can go in either way. Just remember if you ever take them out and refit them make sure you put them back in the way they came out.

Online BSA_54A10

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Re: ring gaps and piston
« Reply #2 on: 13.01. 2011 11:22 »
Rings tend to rotate in use.
I usually fit the 2 compression rings to the sides when new just because I do not like the idea of the ends being on the thrust faces during break in
Bike Beesa

Offline muskrat

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Re: ring gaps and piston
« Reply #3 on: 13.01. 2011 12:02 »
You know the gap shouldn't go over the pin either Trevor  *smile*. Pistons are not round and gap would be more exposed there. 45 degrees from axis is best.
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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