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jrcgaf364

How important is ring gap placement on a piston?

19 posts in this topic

I have always put the gaps of the rings where the manual said to. Works fine... Now I got this dude sayin that it causes premature cylinder wear. Im gonna stick to the norm but just wondered if this guy is a complete moron or an idiot :applause:

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Just set the ring gaps were the manual says, I think Yamaha knows a thing or two about how their engines should be put together. I havent seen any premature cylinder wear in my bike.

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I have always put the gaps of the rings where the manual said to. Works fine... Now I got this dude sayin that it causes premature cylinder wear. Im gonna stick to the norm but just wondered if this guy is a complete moron or an idiot :applause:

Hehe, maybe you can suggest a drug test for him?

The only time I don't buy what the manual says is how to break in the engine.

Otherwise, the old say RTFM is on it's place. Today's manuals are something else than the horribly translated booklets of the seventies.

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Premature cylinder wear?? How the hell does he figure that, and what exactly does he suggest?

The gaps are placed at the "45's" (45, 135, 225, & 315 degrees around the cylinder) to keep them away from two areas; the front and rear walls, which are the thrust zones, and the sides, where there is little or no piston skirt below the ring lands to help baffle against leakage or direct oil splashing. Of course, the gaps are always staggered within the two sets of rings, compression and oil control, to avoid straight through leakage from gap to gap.

Let your friend build his engines any way he wants, you're doing it right.

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The ring placement is important, but not because of cylinder wear, its to keep the oil from getting into the combustion chamber. We made a mistake on my TTR when putting the 150cc kit on. The first time we ran it, the bike smoked more than a 2 stroke. We disassembled it to find the gaps were all aligned. Just do what the manual says and you should be fine

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I never realized It was that important. I allways staggered them around randomly....I always thought they would start walking around when you run the engine, esspecially on a new bore that is close to perfectly round...

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Lets get back to the reason for this thread. END GAP. Why is there end gap? Isn't it to allow for expansion. What do you think would happen if the ring expanded enough for the ends to meet. Now you have cylinder wear!!

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The question was on the importance of the position of the ring gaps, not the existence of and end gap.

Besides, your answer addresses the need for a minimum end gap. The gaps exist be cause the rings need to be able to expand outward as they wear to be able to seat securely against the cylinder walls, which they would be unable to do if they were made as a full, gapless circle.

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Premature cylinder wear?? How the hell does he figure that, and what exactly does he suggest?

The gaps are placed at the "45's" (45, 135, 225, & 315 degrees around the cylinder) to keep them away from two areas; the front and rear walls, which are the thrust zones, and the sides, where there is little or no piston skirt below the ring lands to help baffle against leakage or direct oil splashing. Of course, the gaps are always staggered within the two sets of rings, compression and oil control, to avoid straight through leakage from gap to gap.

Let your friend build his engines any way he wants, you're doing it right.

Holy crap, are you a mechanic or something? In all of your posts, you sound like you have an open motor on your desk right there to look at before you post. :applause:

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You dont get that kind of understanding from just a book. I have a manual for my bike, and I still dont understand my bike even a tenth as well as he does.

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Holy crap, are you a mechanic or something?
Yes, I am, as a matter of fact. I was a professional motorcycle mechanic and builder (both race bikes, engines, and customs)for Norton/Matchless, Yamaha , and independent shops, and a Chevrolet, Ford, and ASE certified Master Technician for some 30+ years. Now I do computer and network support, but no one works on my bikes but me, other than machine work, and I'm very choosy about who does what to my cars.

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Yes, I am, as a matter of fact. I was a professional motorcycle mechanic and builder (both race bikes, engines, and customs)for Norton/Matchless, Yamaha , and independent shops, and a Chevrolet, Ford, and ASE certified Master Technician for some 30+ years. I build wheels for fun and I have a new best friend who's name is Open Class.

Edited for truth. :applause:

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Yes, I am, as a matter of fact. I was a professional motorcycle mechanic and builder (both race bikes, engines, and customs)for Norton/Matchless, Yamaha , and independent shops, and a Chevrolet, Ford, and ASE certified Master Technician for some 30+ years. Now I do computer and network support, but no one works on my bikes but me, other than machine work, and I'm very choosy about who does what to my cars.

I knew it!

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