Piston too low in cylinder?

Marty1028
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Marty1028
Edited Date/Time 10/17/2019 11:55am
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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Paul_Pitzonka
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Paul_Pitzonka 10/16/2019 1:54pm
10/16/2019 1:54pm
That’s too low... any spacer on the base of the cylinder? Incorrect piston?
Marty1028
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Marty1028 10/16/2019 1:59pm
10/16/2019 1:59pm
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.
Marty1028
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Marty1028 10/16/2019 2:00pm
10/16/2019 2:00pm
Got a direct reading with a caliper. It’s sitting 5.6mm down in the cylinder

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Marty1028
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Marty1028 10/16/2019 2:16pm
10/16/2019 2:16pm
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.






Marty1028
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Marty1028 10/16/2019 2:25pm
10/16/2019 2:25pm
Pictures of 96-00 cylinder and head






karlz
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karlz 10/16/2019 3:22pm
10/16/2019 3:22pm
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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mxrose3 10/17/2019 7:48am
10/17/2019 7:48am Edited Date/Time 10/17/2019 8:03am
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.
Marty1028
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Marty1028 10/17/2019 9:53am
10/17/2019 9:53am
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...
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.
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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mxrose3 10/17/2019 11:36am
10/17/2019 11:36am Edited Date/Time 10/17/2019 11:57am
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 motor.
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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