Piston too low in cylinder?

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10/16/2019 1:27 PM

This is where tdc is in my 2000 rm125. It’s sitting about a 1/4 of an inch down in the cylinder. Isn’t this way too low? Shouldn’t it sit higher at tdc?
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2009 RMZ 250 (sold)
2004 LTZ 400
#nukethequads

10/16/2019 1:54 PM

That’s too low... any spacer on the base of the cylinder? Incorrect piston?

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10/16/2019 1:59 PM

Paul_Pitzonka wrote:

That’s too low... any spacer on the base of the cylinder? Incorrect piston?

Nope no spacer. Stock head gasket. Piston seems stock to me.

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2009 RMZ 250 (sold)
2004 LTZ 400
#nukethequads

10/16/2019 2:00 PM

I suggest you have an incorrect piston.

Paw Paw

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10/16/2019 2:00 PM

Got a direct reading with a caliper. It’s sitting 5.6mm down in the cylinder

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2009 RMZ 250 (sold)
2004 LTZ 400
#nukethequads

10/16/2019 2:16 PM

When I picked this bike up the PO gave me two cylinders. One is (I presume) a 94 cylinder at stock bore. The other is (I presume again) a 96-00 cylinder that’s been bored out with a steel sleeve to 56mm.

Pictures of 94 cylinder and piston. Photo
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2009 RMZ 250 (sold)
2004 LTZ 400
#nukethequads

10/16/2019 2:25 PM

Pictures of 96-00 cylinder and head Photo
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2009 RMZ 250 (sold)
2004 LTZ 400
#nukethequads

10/16/2019 3:22 PM

Going off my daily experience of selling mx parts. It looks that a 1997-1998 rod has been fitted which is 5mm shorter.

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10/17/2019 7:48 AM
Edited Date/Time: 10/17/2019 8:03 AM

Marty, I think we went over this in the other thread that you had with the power valve issue.
It looks like you have a mix and match bunch of parts with that bike.

The 87-96 engine had a 105mm long connecting rod.
The 97-98 engine had a 100mm long connecting rod.

So it looks to me like you have a 97-98' bottom end on that bike and you are trying to fit a pre-96' cylinder to it.
Looks to me like you either need the correct connecting rod on the crank, or you need to buy a 97-98' cylinder for it (which is probably shorter in length also? not sure if Suzuki shortened the cylinder, or the cases).
Does the sleeved cylinder fit? It may be the correct cylinder for it.

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10/17/2019 9:53 AM

mxrose3 wrote:

Marty, I think we went over this in the other thread that you had with the power valve issue.
It looks like you have a mix and ...more

Nope. The sleeve cylinder has the same result. Do you know where to Lookup the engine codes? I’m thinking this isn’t a 2000 motor.

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2009 RMZ 250 (sold)
2004 LTZ 400
#nukethequads

10/17/2019 11:36 AM
Edited Date/Time: 10/17/2019 11:57 AM

Marty1028 wrote:

Nope. The sleeve cylinder has the same result. Do you know where to Lookup the engine codes? I’m thinking this isn’t a 2000 ...more

Yeah, I don't think it is a 2000 bottom end.
Check this link to cross reference your engine numbers. the numbers may lead you to a clue on what year the cases are at least.

http://www.oem-cycle.com/SUZUKIRM125BIKEID.shtml

But after looking at that, it looks like the cases are basically all the same between 89' and '2000 (they all start with F114-).
The only difference would be the connecting rod on the crank. So that most likely tells me that you probably have a 98' bottom end, or a 2000' bottom end with a 98' crank/connecting rod installed.

For reference, the rod lengths on the crankshafts from center to center are as follows:

87'-96' - 105mm
97'-98' - 100mm
99'-03' - 102mm

Not sure if you can get an accurate measurement of the connecting rod with it installed in the bottom end.

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