Author Topic: 1975 RM125S vs M Pistons  (Read 837 times)

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Offline minifig-phil

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1975 RM125S vs M Pistons
« on: December 02, 2017, 04:54:43 AM »
Can someone post the part numbers of Suzuki Pistons and Rings for the '75 RM125S Model Please.
I can only find Part numbers for the M model.
I have a stock piston here that has thinner rings and I'm wondering if the S model came that way.


Offline cwanedwiver

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Re: 1975 RM125S vs M Pistons
« Reply #1 on: December 02, 2017, 05:06:22 AM »
STD  "s"     Piston  12110-41730                                                 STD "s"  Rings   12140-28740
0.25  "s"     Piston  12110-41729                                                 0.25 "s" Rings   12140-28770
0.50  "s"     Piston  12110-41739                                                 0.50 "s" Rings    12140-28780

Offline TT5 Matt

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Re: 1975 RM125S vs M Pistons
« Reply #2 on: December 02, 2017, 02:55:11 PM »
Yeah S piston rings were very thin to reduce friction but they also wear a lot faster.I've got some spare std size S rings and a .5 over S piston though no rings

Offline minifig-phil

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Re: 1975 RM125S vs M Pistons
« Reply #3 on: December 02, 2017, 10:13:15 PM »
Thank-You!!! :)

Offline Rupert Prior

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Re: 1975 RM125S vs M Pistons
« Reply #4 on: March 09, 2018, 11:41:36 PM »
this may be ancient history to some, but Suzuki part numbers got confused on the M to S change over so list all the pistons and rings to supercede to a mix of both. the problem is when they "pick" the parts they reverse the supersession so M or S pistons can be matched with M or S rings. nobody really uses S rings any more  so stick with M or TM or TS or TC or outboard motor pistons and rings, but cut the skirt to suit.

Offline OverTheHill

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Re: 1975 RM125S vs M Pistons
« Reply #5 on: March 13, 2018, 08:09:45 AM »
Not sure if relevant but i had an S back about then--traded it on my yz250c & had more fn on that than the C, but anyway, thinking back to replacing rings or piston & rings the thin rings are gap'd to the ring peg 'not stepped over the end of it' or under it. Consequently if you sit the rings in the bore they'll have about 40 thou end gap [or gap equal to the peg size]. Peg comes right to ringland edge pretty much. In other words don't worry if you sit them in the bore & think you have the wrong size. All that's thinking back 40 years [is that right-- hell]. Broke the end off the crank in mid air on full song too [ran outa spark lol], damn near went over the bars when it landed. Re the rings--it's the wear where they scratch past the ports that's the important bit rather than end gap--consequently new rings always sharpens up a two stroke with big holes [ports]. That my opin ion anyway--others might differ.