2003 KDX 220 Cracked Piston

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John McIntosh
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2003 KDX 220 Cracked Piston

Post by John McIntosh »

I have been holding off on replacing my piston but all of the horror stories made me decide to get it done this winter. I bought a Wisco piston and got to work with a friend who knew what he was doing. By the way, my friend tried to talk me out of replacing my piston. He thought I was crazy to replace a perfectly good piston. Local shop owners told me the same. Any way, when we opened things up, we found that my piston was cracked. I guess I must have got it just in time. Have any of you found a piston cracked but not blown? I guess I got lucky. :shock:
Mack (Bel Air, Maryland)
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Post by Indawoods »

In their face eh Mack? :grin:

I'm glad you had the sense to follow your gut instincts. :supz:

I have heard of cracked skirts on the 220....
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Post by canyncarvr »

Yep.

There is a reason green people that have been hanging around for the past eight or so years (and more) are of the opinion that the 220 piston needs to be replaced.

NOW would be a good time for the rest of you if you haven't done it already.

I recall only one 220 rider...lived in Howareya..that replaced his piston before he even fired up his brandy new bike.

Most others scoff, guffaw and generally think the whole idea is stoopid.

Congratulations! A broken piston can be as easy on you as getting you a bike that just quit running.

...or it can take out the whole engine..top to bottom.

Re: 'He thought I was crazy to replace a perfectly good piston.'

You might be, anyway (crazy I mean) :wink: Unfortunately the subject of the matter is NOT '..a perfectly good piston.'

Good job!!! :supz:

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Post by GS »

Well..
Seems that I, too, pondered the sense of changin that what ain't showin no signs of being "broke"

BUT, after looking closely at the unbelievably poor quality of the OEM piston casting that I had sorta reluctantly removed :shock: :shock: :shock: ( think homemade with mondo beer in your belly..or, if that's meaningless to you, try... 1st generation imported "rubber" Chinese tools)

I AM CONVINCED IT AINT NO SILLY NET RUMOR THESE THINGS ARE CRAP !!

Your mileage may vary...........but at least you'll know who to really blame...... :blink:

Way easier to change now, than a little bit too later...too! :oops:
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rollerman
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Post by rollerman »

this site made me see the light changed my 220 piston after 25 hrs now i feel better next is carb and head mod..
03 kdx 220 mine
05 pw 80 son
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Jeb
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Post by Jeb »

I, too, heard of the risk and decided to install the Wiseco . . .

'looks like here's yet another example of why that was the right thing to do.

Thanks kdxrider !!
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Re: 2003 KDX 220 Cracked Piston

Post by kdxquebec »

>|QBB<[/url]
John McIntosh wrote:Have any of you found a piston cracked but not blown? I guess I got lucky. :shock:
Yes

When my riding buddy openned His motor...He found this.

:? I took the picture!

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Steve Sims
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Post by Steve Sims »

I know this has been discussed before, but roughly how difficult, time consuming, and expensive is a piston replacement using a Wiseco and doing the work yourself? (Keeping in mind I'm not much of a mechanic, but don't mind trying).
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Post by KDXer »

If you have a manual you should be fine. There are step by step picture tutorials floating around the web plus the wealth of info here. It cost me around $200 and a few hours to reassemble everything. The cleaning of the parts (power valve, etc) was the time consuming bit for me.

Good luck...

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Post by Jeb »

>|<>QBB<
Steve Sims wrote:I know this has been discussed before, but roughly how difficult, time consuming, and expensive is a piston replacement using a Wiseco and doing the work yourself? (Keeping in mind I'm not much of a mechanic, but don't mind trying).
If you don't mind trying you're 90% there . . .

PREP:

The service manual is a MUST if this is your first time on this bike. There's an online version (look at the top of the site) that I use and it's fine but, naturally, others like the paper copy. Become VERY familiar with whichever you use.

There are those who don't use a torque wrench but if you're a newbie at this you likely have an uncalibrated arm. Also, note that the cylinder base nuts require an adapter with the torque wrench - your manual should specify type and size (I think it's a 12mm or 13mm). Ask questions if this is puzzling.

Parts: piston, rings, pin, pin bearing, clips (order extras if you can), top end gasket kit (Vesrah, Cometic). Buy a gasket-remover tool (it's like a special scraper).

Read up on cylinder de-glazing. You'll probably want to do that as well - do some searches and ask questions if you need to.

When you get your new piston confirm the tolerances (or find somone with the tools for it). There's searchable material on this.



TIPS FROM A NEWB TO A NEWB, TAKE 'EM OR LEAVE 'EM:

Plan, plan, plan.

Give yourself plenty of time. After the piston is changed out you may indeed think, "that didn't take long" after which you will state so along with the others that can do it "in a few hours" and I will remain silent. If you're like me you won't say how long it took and we will be brothers in silence.

The online manual shows the disassembly with the engine out of the frame. You don't need to remove it - I didn't - but it IS easier to remove the head without the front and aft engine mounts to which the head is attached (even if it doesn't look like you need to).

The nut holding the lever at the end of the exhaust valve actuator shaft lever is LEFT HANDED. Your manual should state this but it's worth reiterating because apparently it is easy to mess things up. There's flat spots on the shaft itself to hold with a wrench while loosening.

Do check the ring gap.

Do be mindful that the arrow on the piston crown should be pointing towards the front of the bike when installed.

Do stuff a clean rag or two under the piston during removal and reassembly so that the circlips don't bounce their way down into your lower end (yikes!).

Consider getting some help getting the cylinder back in place after the new piston is in. If you can't find anybody, I used an Eric Gorr tip: I did this by myself by installing one of the circlips in the piston, starting the piston w/ rings and one circlip assy into the cylinder with the cylinder on the bench. Feed the piston far enough in leaving room to be able to install the pin and other circlip. Using the cylinder studs as a support, attach the half-buried piston onto the upper rod end with the pin and the other circlip. It's a little tricky but once you've got the pin and other circlip in place, simply align the studs with the stud holes in the cylinder and you've got it.

About your circlips - make sure they are seated correctly. This is going to sound silly, but if you "practice" with your old piston and circlips you'll get a bit of a feel for it.

Don't hesitate to ask questions. Hint: best time to ask is BEFORE you get started.
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Post by Steve Sims »

Jeb, thanks for taking the time to give me a heads-up on all of that. It's both useful and frightening! Not really frightening, just a little more involved than what I had figured, but that's alright. Sounds like a good learning project while there is ice and snow on the ground. I would guess to have a bike shop do this would cost probably $250 in parts and another $250 in labor. I would be sick if the OEM piston faulted and screwed up my engine. I just don't get why Kawi doesn't put a better piston in the bike in the first place. KDX's are priced well enough that they could up the quality for another $50-$100 and pass the cost along and I don't think anyone would complain. I sure wouldn't. It would still be a great deal.

Thanks again. I do love this bike. Itching to get out on it again, but the weather has not permitted here. I've only been on one ride since I bought it about a month ago and that was a mud fest. Can't wait for a good, semi-dry day to get it out and see what it can do. The guys on this site were very helpful in making the decision to buy this bike and it ended up being an excellent decision.
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Post by canyncarvr »

Repeated for emphasis: 'There's flat spots on the shaft itself to hold with a wrench while loosening.'

That is not an advisory..that is an absolute necessity!!

It's not particularly involved. Think of ANY process that you do on a regular basis..write it up bit by bit and while it seems simple to if you already know it..when you read the step-by-step that you wrote..it sure looks 'involved', don't it?

A couple other things:

This is true of Pro-X sets, I don't know about Wiseco. DO put the rings in the land (groove in piston) they best fit in. They are supposed to be the same, but I have not found a SINGLE instance where the rings were interchangeable. Personally, I think the Pro-X rings are tapered differently for the purposes of better seating...

TRY each of the two rings in each land. IF there is a difference in fit, place them as they fit best.

Obviously (right?) both rings fit only one way and in one spot on the piston..the pin pressed into the land should make that obvious.

Some have missed it, though!

When you do lower the cylinder onto its base, by putting your fingers into the intake port ensure the rings do not hang up on the port edges on install. Some slight pressure on the ring will usually help the edge of the ring get past the edge of the port.

Once you get it done you'll say, 'Piece-o-cake!!'

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Post by Kawinj »

I'm too lazy to dig around for the pictures of my cracked 05 220 piston with 200 miles on it. Glad you went with your gut.
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Post by Jeb »

>|<>QBB<
Steve Sims wrote: . . . Can't wait for a good, semi-dry day to get it out and see what it can do. . .
It's gonna be great - and just wait 'till you start tweaking jets and needles and adding a pipe and . . .

Don't be too frightened (a little fear will keep you honest when the wrenches start flying). It was only a few months ago that I was where you're at right now!
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