kdx 200 cylinder scoring

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kdx 200 cylinder scoring

Post10:33 pm Jun 13 2012

I started tearing down the motor for crank seals and bearings and found some cylinder scoring. Is this normal nothing to worry with or do i need to do a top end also.
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I checked the compression before tear down and it was good.
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I did'nt clean any parts for pictures. I was not expecting the head to be that clean.
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woodselec
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Post10:41 pm Jun 13 2012

Doesn't look that bad to me. Can you feel what you think is scoring with a fingernail? If you can feel it, time for a replate. If not, then you are probably fine. Just clean it up with a Scotchbrite pad and reuse it.
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SS109
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Post06:59 am Jun 14 2012

There are 3 that you can feel and all the scores are below the exaust port . above the exaust ports is perfectly clear no marks anywhere.
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Post07:15 am Jun 14 2012

scrub it down with a scotch brite pad and some WD-40 and see what it looks like after. Looks serviceable to me.
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Julien D
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Post08:04 am Jun 14 2012

I made a mistake in telling where the scores are they are above the exaust port not below.That puts them in the compression/combustion part of the cylinder. does that make this more of a problem?
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Post10:13 am Jun 15 2012

Eh. Unless you want a *perfect* machine, I would just clean it up and run it. I have seen much worse looking cylinders still in service. In fact, I would guess that if many of us tore our motors down right now, they would probably look very similar to yours.
JMO.
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Post10:39 am Jun 15 2012

Agreed.
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Julien D
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Post08:35 am Jun 16 2012

Thanks for all the info. I am going to clean it up and run it
the bike ran very strong before tear down.
Hopefully my parts will be in next week and i can get running.
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Post08:58 am Jun 16 2012

One more question i thought of.
After i clean the cylinder with a scotch brite pad and break the glaze will my old rings be ok or do i need new rings?
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Post11:00 am Jun 16 2012

Would be best to put new rings in. They're cheap enough.
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Post08:32 pm Jun 16 2012

david wrote:Would be best to put new rings in. They're cheap enough.

+1
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Post09:15 am Jun 17 2012

does anyone know if rings for a 87-88 will work in a 2002. I found a set of 87-88 oem rings.
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Post02:40 pm Jun 17 2012

I'm gonna go out on a limb here and say "no". If it said "87-02" I'd say yes but it says "87-88". :mrgreen:
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Post03:32 pm Jun 17 2012

I believe they are the same from 86+.
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Post03:44 pm Jun 17 2012

I'm pretty sure the ring design (shape) changed from the C model to later models - but that doesn't mean they won't work. See if the piston locator pin fits the ring ends properly - I know that I had piston and rings from my c models and decided not to use them on later models because of the changed design, but I can' t remember the specifics.
97 KDX200 02 YZ125 forks, 04 WR250 triples, FMF woods & silencer, 607 reeds, rb striker
01 KDX220 02 yz125 forks & triples, FMF rev, silencer, 607 reeds, rb head mod, kdx200 carb
87 KDX200 04 yz250f forks & triples, H model rear disk brake, FMF pipe, boyesen reeds
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Post04:42 pm Jun 17 2012

I guess the OEM stuff changed then? Never had a set of C series rings in my hand. All the aftermarket piston kits for the 200 are specified as 86-2006. Since the pro-x parts (pistons and ring sets) are claimed to be interchangeable with the OEM bits, I just assumed that any pro-x or oem rings from 86+ should work on any oem or pro-x piston from 86+.
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Post05:47 pm Jun 17 2012

I know the wiseco rings and pistons crossed over just fine, but the oem rings changed (I think they went to a taper type design for more compression) - the early ones may work in the later pistons tho', but I seem to remember something different regarding the pin configuration (maybe set at a different height?). Then again, trusting my memory for over 20 years ago is iffy...LOL...

Regarding wiseco, I'm in the process of rebuilding an 87 and it has a wiseco piston in it, so I read the numbers on the piston top. Some guy is selling an old (but unused) wiseco piston from back in the day on ebay, it had the same part numbers and I could also read the ring part numbers on the ring package that came with it. Wiseco uses the same ring part number today so I just ordered a set for a bike that hasn't been worked on for 15 years or so. Pretty cool.
97 KDX200 02 YZ125 forks, 04 WR250 triples, FMF woods & silencer, 607 reeds, rb striker
01 KDX220 02 yz125 forks & triples, FMF rev, silencer, 607 reeds, rb head mod, kdx200 carb
87 KDX200 04 yz250f forks & triples, H model rear disk brake, FMF pipe, boyesen reeds
'08 WR250R (the dual sport)
09 Husky TE310 (factory plated dirt bike)
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kawagumby
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Post07:15 pm Jun 17 2012

Thanks for all the info
Just to be on the safe side i will order a new set of rings.
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