A size piston, B size cylinder?

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Terrence Sprocket
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A size piston, B size cylinder?

Post by Terrence Sprocket »

I have a E series size B cylinder. My piston has no indication on it whether is a wisco, pro x, kawi, etc. The only things on in is the arrow ( for direction of flow) and a large A on the top. So, I'm assuming it's a Size A. What's the bore of the A piston? 65.95mm? I just sent my cylinder for plating and I prob should've sent my piston with it. Do u think they'll plate to the B size? The B is right beside the exhaust flange and is very mildly stamped. I wonder if they'll even see it. Running an A in a B cylinder would be fine ehh? I'm just worried that they'll bore it to wisco's STD size of 66 mm. In that case, I'll have to buy a new piston. Don't really have the extra cash tho, I just forked out Alot on the cylinder, which I should have back any day now.
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Julien D
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Post by Julien D »

So this piston is used and you're going to throw it in your freshly plated cylinder?

Anyway, the difference between an A and B piston is .01mm. Not enough to cause you any problem. I would still check your clearance. The A piston is 65.94mm, the B piston is 66.95mm.

If you sent the cylinder without a piston, they will bore to Kawi factory specs. Wiseco doesn't come into play unless you send a Wiseco piston with it.
Stock factory cylinder bore is 66.016 - 66.031. The re-plated cylinder should fall in between there. Even if they plated to the tightest tolerance of 66.016 your B size piston, which is 65.95mm, gives you .066mm clearance. This should be fine. If you mic out the cylinder I'll bet you find it in the 66.02 range. If you have a shop manual, all this info is in the top end section.
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Slick_Nick
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Post by Slick_Nick »

Yeah, buy a new piston please...
'00 KDX 220R
Terrence Sprocket
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Post by Terrence Sprocket »

I'm not usually one for using used pistons. But this A size piston looks as if it just came out of the box. I know it sounds very hard to believe, but I can assure u that it's absolutly re-usable.
Good to here that they use factory specs. I just wanted to be sure . It's good to see those cylinder specs too so I have something to go by. I think the previous owner of my bike just threw a complete top end on and a brand new piston. It's a 1990 model (e-2) with a 89 top end (e-1). The cylinder was worn down quite badly, but no scuffs or imperfections. I only put a handful or hours on it b4 tearing the top end off. I'm going to wait to see the cylinder specs b4 I purchase the new rings.
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Julien D
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Post by Julien D »

If that piston has an A stamped on top, it's either OEM or a Pro-X. It's certainly not forged. You're going to be buying standard rings anyway, so why wait? The OEM/Pro-X A,B,C,D size pistons all use the exact same ring set.
Terrence Sprocket
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Post by Terrence Sprocket »

Ok. I wasn't sure if they used the same rings for all the standard sizes. Thanx for the input. I'll order the new rings on my way in town. So, will oem rings work on a Pro X piston? I don't see any other markings in the piston that would indicate it being a pro X. But I'ld hate to find out that it is pro X and order rings that won't work. I know what u guys are going to say, " just order a new piston to be sure" lol :cool:! But I really don't see a point cause my piston is really flawless.
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Post by kawabunga »

Good answers Juliend
reviving old war-horse.
Terrence Sprocket
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Post by Terrence Sprocket »

Thanx for helping. It seems like u guys can answer anything I throw at ya's. Greatly appreciated! :grin:
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Julien D
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Post by Julien D »

Pro-x manufactures the OEM pistons, so they are exactly the same. No worries there.
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