Pro-X piston sizing

[canyncarvr]

KDXs come with several different sized pistons. On the cylinder head and cylinder you will find an alpha stamp; A,B,C,D usually. There may be a letter further down the alphabet.

Kawasaki sorts Pro-X pistons by size, using manufacturing tolerances as a guide. Each alpha designation is .01mm, a 'B' being bigger than an 'A'.

This isn't a huge deal...seeing as we're talking about a difference of less than 1/2 of one thousandth of an inch....but it IS something to keep in mind.

If you buy a piston from your local Kawi dealer you will not be able to specify what size of piston you want. You will probably get a 'B' piston (they are stamped on the top, too), but not always.

To get THE size you want, you will have to order it from a Pro-X dealer. They have different part numbers for their alpha-designated pistons.

Of course...one piston ring set fits all of 'em. That kind of shows how important the alpha differences are, 'eh?

Click here...

...then on 'catalogs'...'online catalog'... make/model/year... 'oversizes**' to see the sizing chart I'm talking about.

Sorry, I cannot attach that chart here.

Note this concerns kdx200 pistons. If you are replacing your 220 piston DO NOT use the oem Pro-X piston as a replacement. You know they tend to come apart...right? Use (ugh..ick..spit) Wiseco instead!

[KDXGarage]

I read somewhere that whoever is really making the pistons is making the OEM and Pro-X pistons. Something like that.

Thanks for the info.

[canyncarvr]

OEM is Pro-X.

Don't ask why 200 pistons are good and 220 pistons stink if they come from the same outfit.

Well...not if you expect a sensible answer.

[KDXGarage]

Oh. I didn't mean to say anything about 220 pistons. I was thinking 200.

I did some searching and ART brand was what I was thinking of earlier. Like most things, I could search for dayyyyys.

You are right to point out that what you get from a dealer is what you get. That makes sense to me. That's a good suggestion to get a Pro-X.

Thanks.

[Indawoods]

For some reason it takes the Wiseco piston a lot longer to warm up... And I have even heard rattling before they come to temp. I don't understand that... but for that reason I am going Pro-X.

[BJH]

For some reason it takes the Wiseco piston a lot longer to warm up... And I have even heard rattling before they come to temp. I don't understand that... but for that reason I am going Pro-X.

I'm not sure if it correlates, but I think it may. When I used to put together hot rod car engines I would always hear the same thing from Forged pistons over cast ones. The forged pistons are more dense. Therefore they don't expand from heat as fast or quite as much as cast. So they maintain cold slop longer than cast. Wiseco pistons are forged. At least mine is.
A forged piston is still superior to a cast piston though. At least that's my opinion.
The ultimate solution would be to have a heat treated hypereutectic piston. They have a very high silicon content for lubricity and are very strong when heat treated. Yet they have the faster expansion rate of a cast piston. Problem is I don't know of anyone that makes them for KDXs
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Hinduism forums

[mudpack]

The ultimate solution would be to have a heat treated hypereutectic piston. They have a very high silicon content for lubricity and are very strong when heat treated.

Someone is thinking of silicone, not silicon. Silicon is a very hard element, but has no lubricational properties....it is very wear resistant.

[fuzzy]

Indeed forged vs cast. The wiseco is also like an "F" Pro-X so depending on what your cylinder is it's going to be on the minimal side of clearance...Which is good, IMO. Always run the tightest clearance you can get away with. Makes more power, lasts longer...Regardless of cast vs forged. DO need to warm up, which is also always a good thing.

Preference thing really. The forged piston is stronger, but not really needed in our application (fairly low rpm, low compression, low stress). My guess is it will last longer, but maybe(possibly?) at the expense of a few mirons of plating? The forged piston will love better in a high-compression setup...Especially alky/nitro/etc. In general, the cast piston will make more power in our application. A cast piston can be prone to breakage. <all this from what I have read from some serious experts on pistons...Not from my personal knowledge of metallurgy>

The 200 piston seems fine as a cast unit, 220 doesn't. May not be pro-x's fault, but could potentially be more of a problem w/ wrist-pin locale vs bore/etc design from the get go. The forged piston reliability could be an easy fix for something that wasn't quite right. <speculation> Don't think anyone else makes a 220cc cast piston to try this out. Most aftermarkets are forged (for whatever reason...Prolly cause they sell). Forged is the best, right?

Hyperuretic's are great. Cast, yet strong. Generally the best of both worlds when the ultimate strength of a forged piston isn't needed (14:1 w/ a lil nitro )

[Curious George]

Do yourself a favor and get the Wiseco.
Night and day difference in quality and just the design.
The Wiseco piston is fully knurled or technically machined with
very small record size grooves on the entire skirting. The oil retention
is twice what a stock piston can provide and will drastically extend piston
life.

Any forged piston will expand slower ,,,, but any of us should let the bike come up to temperature before we ride anyway ,,,, so that's not really a
big deal .

There's a reason why Wiseco has been around as long as they have ,,,,
They just make a Great Product !!!