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Piston ring set. which way round please?

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I've just had my badly smoking 76 xr75 rebored as I'd tried everything else just about. It now has an 82cc DG kit about to be installed. A quick question though, does anyone know which way round to put the rings? I know how to mount the bottom set ( the two thin ones and the crinkly one). But for the upper 2 rings I have 1 plain black one, and one black one with a silver edge around it. Should the silver edge ring go at the top of the piston? Or does the plain black one go top? Help please- :naughty:I know I should have known....

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I can never remeber either, but I think it's silver on top. Also, makes sure there's a little mark on the ring as well and that goes facing up. Also, offset you spaces, usally at 4 and 8 o'clock from the front of the motor looking down.

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Are you piston rings straight cut or angle cut? If angle cut you can look at the locating pins on the piston which will be either on the upper or lower half of the ring slots. Striaght cut I will have to double check my instruction manual for the kit I did as it told in there. I"ll look and get back to you as I wouldn't want to tell you the wrong thing. :cry: Good luck with it!

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They are straight, with no locating pins. I found out from a shop that the silverone goes at the top, thanks anyway!

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Did you find the mark? I installed a set upside down once, and it blew the base gasket and I had to do it all over again. Just one of those things that make you hit your head against a wall. Or take an anger management class. :cry: :cry: :cry:

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There were some very small letters on them, I'm assuming thats the mark. I put it together but its very tight. SoI'm going to strip it again, don't want to damage anything trying to start it. I've head that I may need to file doen the ends of the rings if its tight? I'm going to try them in the cylinder without the piston to check there is sufficient clearance. Sounds sensible? or am I mad and ill-informed?

cheers :cry:

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fraser, You are right on track. There are min. and max. ring "end gap" clearances that you have to follow on a top end rebuild.

If the ring gap is too tight you can file the ring end to get min. spec.

Also a common practice among engine builders is to place the rings (one at a time) into the cylinder bore and hold the cylinder up to a light while checking for the ring being out of round. If there is a gap between the bore and the new ring than the ring may be damaged (dropped or d-shaped) and will never break in or properly seal no matter how long you run it....Karl

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Oh Yea, As I remember, when in doubt any marking on a ring should face upward (rule of thumb)...Karl

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Yeah i was having a wee bit o' trouble gittin the piston rings the in the right slot as one had one letter on it and the other had two. I ended up putting the writing to the top and the shiney one (edge machined down on angle) in the second compression slot. I did check the ring gap clearances too and they were ok. Its running good now so I assume its back together properly.

John

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Checked the ring gap, and the shiney edge one was way too tight, rebuilt it with the shine edge on top, its running great, much relief, only problem is now the clutch is slipping a bit, always something! Went practising on my 250f yesterday, took the 75 along and went out in ther kids group, fantactic on the corners losing enormous amounts on the straights to new 85s lol. Managed a small double despite diabolical original suspension! :cry:

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