Suzuki RM125K 89

suzuki
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46
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2/10/2016
Location
GB
Edited Date/Time 12/21/2021 12:56am
Hello Everyone,
Just bought one of these to restore, It's in pretty rough shape.I seem to remember them having reliability issues back in the day with pistons/powervalves and cranks.Does anyone know what the issues were and how to prevent them and how do I make it as fast as an 89 CR ?
Thanks
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Slingshot92
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179
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3/26/2015
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Ylöjärvi FI
2/10/2016 9:42am
Following. At least the AETC power valve parts might fall into cylinder once worn out. Same problem at least from -89 to -95.
Mixon848
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335
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Location
Oakley, CA US
2/10/2016 2:48pm
suzuki wrote:
Hello Everyone, Just bought one of these to restore, It's in pretty rough shape.I seem to remember them having reliability issues back in the day with...
Hello Everyone,
Just bought one of these to restore, It's in pretty rough shape.I seem to remember them having reliability issues back in the day with pistons/powervalves and cranks.Does anyone know what the issues were and how to prevent them and how do I make it as fast as an 89 CR ?
Thanks
On the 1989's the Power Valves gum up very badly very quickly and the cylinder runs hot.

Also the crank seal should be replaced with that of the 1988 Suzuki RM125.

As far as making it a CR125 beater many will "lie" and say it can't be done having never raced one. It can and it takes:

FMF or DG Pipe (the Pro Circuit Pipe for these bikes weren't good)

FMF Ram Valve or Boyesen RAD Valve

If you are fast enough to keep the motor singing (fast Intermediate or Pro) then throw on a 38mm Carb. It is a tight fit but it works.

You don't need porting to make them scream.

Enjoy that bike. They are fun.
wolfy0067
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534
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8/14/2014
Location
Wernersville, PA US
2/12/2016 6:28am
If you can find the parts cheap, I would up-date to 90 cylinder and head and ports are a better setup, look at the transfers they have a better shape and capacity, also the back scavenge port was opened up to flow better. I think past 91 you may have trouble retrofitting. Do your homework.

As stated above they where great bikes, they would be on the pipe and down a straightaway before the Honda came on the pipe.
suzuki
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46
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2/10/2016
Location
GB
2/12/2016 7:18am
Thanks for the replies. I have a pro-circuit pipe and silencer (hope it's not too bad) and Boyesen RAD valve so I'm hoping they work well together. Do you know if the power valves swap between the 89 and 90 cylinder as these are very hard to find in good condition and usually very expensive?
I did hear there was a crankshaft problem. Does anyone know about this?
Thanks Tim

The Shop

Mixon848
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Oakley, CA US
2/12/2016 7:34am
suzuki wrote:
Thanks for the replies. I have a pro-circuit pipe and silencer (hope it's not too bad) and Boyesen RAD valve so I'm hoping they work well...
Thanks for the replies. I have a pro-circuit pipe and silencer (hope it's not too bad) and Boyesen RAD valve so I'm hoping they work well together. Do you know if the power valves swap between the 89 and 90 cylinder as these are very hard to find in good condition and usually very expensive?
I did hear there was a crankshaft problem. Does anyone know about this?
Thanks Tim
Pro Circuit Pipe and Silencer combination will work on the bike (especially mated to the Boyesen RAD Valve), it is just the FMF Pipe and Silencer are (were) a better combination for this bike for fast Intermediates or Pro's. But you have no worries. It will still fly.

The 1989 gets air leaks at the Crank Seals. If jetted lean and you get a leak, you are siezing for certain. Also watch for the bike using up tranny fluid. Just check it a little more frequent than other bikes you have or have had. The oil blows out of the relief tube by the Power Valve.

People said these things were slow, and with the Stock pipe and Silencer and Reeds they were. But my Trophy Case has a lot of Trophy's, Pins and Ribbons do to the 1989-1991 Suzuki RM125's. With the 1991 being my favorite and I am currently building one from the Frame Up.
2
Slingshot92
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179
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3/26/2015
Location
Ylöjärvi FI
2/12/2016 8:05am
I have heard that at least the 1990 model cylinder head was not perfect. The cylinder cooling was not sufficient and the engine could temporary overheat / seize the engine.

-89 was also more tricky to maintenance since -91 was the first model with a separate clutch cover.
wolfy0067
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534
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8/14/2014
Location
Wernersville, PA US
2/12/2016 9:34am
Think 92 was the first year they added stuffers to the crankshaft, some of them where coming loose, someone forgot the Loctite
mxjeff575
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408
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7/14/2011
Location
Festus, MO US
2/21/2016 12:37am
I also have an 89 RM125 I am fixing up for vintage racing. I can't find a Pro-Circuit pipe for the 89, but I can find them for the 90. Will it work decent on the 89 cylinder or not?
1
mx200
Posts
21
Joined
3/9/2014
Location
BR
2/23/2016 4:03am
Hi, guys!

This is what Suzuki France did to their bikes in 1989. Enjoy!





1
Slingshot92
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179
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Ylöjärvi FI
2/23/2016 5:41am Edited Date/Time 2/23/2016 5:42am
Would enjoy more if this was written in english. I'm sure that most of us don't understand anything about the article. Smile
1
philG
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10212
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5/12/2012
Location
GB
2/23/2016 6:41am
we have one that is currently undergoing a rebuild.. cant wait to see what it goes like.
mx200
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21
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3/9/2014
Location
BR
2/23/2016 7:58am
Ok, guy!

First page was translated. I've tried to make it as clear as possible. Just wait until I get the second part done.



4
wolfy0067
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Wernersville, PA US
2/23/2016 10:07am Edited Date/Time 2/23/2016 11:19am
mxjeff575 wrote:
I also have an 89 RM125 I am fixing up for vintage racing. I can't find a Pro-Circuit pipe for the 89, but I can find...
I also have an 89 RM125 I am fixing up for vintage racing. I can't find a Pro-Circuit pipe for the 89, but I can find them for the 90. Will it work decent on the 89 cylinder or not?
You will need to look at the exhaust pipe spigot, they were changed a bit each year, remembering the 89 exhaust was the biggest. you may be able to cut off the spigot and have rewelded. Did you check with Dyno Port, he may be able to help.
suzuki
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46
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2/10/2016
Location
GB
2/24/2016 12:59am
Thanks for the info ,especially the French magazine article and translation ,Anymore info would be great
mxjeff575
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Location
Festus, MO US
2/28/2016 7:08pm
Well, i decided to gamble and ordered a 90 Pro-Circuit pipe. I just got an old 89 RM125 and started tearing it down. I fitted up the 90 pipe real quick. It seemed to fit (although i didn't mount up any pipe brackets). I'll update this in a few weeks when it officially goes back together.
Slingshot92
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Ylöjärvi FI
2/28/2016 11:39pm
Cylinder modifications done according the article. Thanks again. Smile









1
suzuki
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2/10/2016
Location
GB
2/29/2016 4:29am
Cylinder modifications done according the article. Thanks again. :) [img]https://p.vitalmx.com/photos/forums/2016/02/28/126046/s1200_WP_20160228_18_39_26_Raw.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2016/02/28/126047/s1200_WP_20160228_18_39_54_Raw.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2016/02/28/126048/s1200_WP_20160228_18_40_30_Raw.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2016/02/28/126049/s1200_WP_20160228_18_40_50_Raw.jpg[/img]
Cylinder modifications done according the article. Thanks again. Smile









The porting work looks really good. What year cylinder is that as it has a liner and o ring grooves ?
Slingshot92
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Ylöjärvi FI
2/29/2016 5:40am Edited Date/Time 2/29/2016 12:06pm
I checked that Suzuki started using o-rings in the cylinder head from 1990 forward.
Slingshot92
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179
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3/26/2015
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Ylöjärvi FI
3/2/2016 4:41am
What is the right setting for the power valve knob from the 'rest' postion. I.E. how many rounds spring tension?
9/9/2021 5:33pm
Does anyone know where I can find exhaust for a 1989 rm 125 or what other year pipe will work? I'm convinced there isn't 1 left on the planet
Mixon848
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335
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Location
Oakley, CA US
9/9/2021 6:19pm
Does anyone know where I can find exhaust for a 1989 rm 125 or what other year pipe will work? I'm convinced there isn't 1 left...
Does anyone know where I can find exhaust for a 1989 rm 125 or what other year pipe will work? I'm convinced there isn't 1 left on the planet
https://dynoport.com/model/suzuki-125-rm-1989/
I did a list of every single 1989, 1990, 1991 and 1992 exhaust pipe for sale through out the world in my group on facebook. They are out there you just have to be willing to put in the same amount of time that you put in daily for your employer finding them.
2
9/29/2021 5:00pm
Is there any other year that will work on the 89, or atleast only require minimal fabing?
9/30/2021 8:23am
I just bolted up a FMF Pipe/Silencer combo, had the porting cleaned up and spent the rest on suspension mods..

I did break a few frames under the foot pegs, I would watch for that.
450exc115
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681
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11/6/2014
Location
Hebron, CT US
9/30/2021 1:58pm
Is there any other year that will work on the 89, or atleast only require minimal fabing?
89-91 are the same fitments. The 90-91s have an extra mount down by the lower frame rail that the 89 didn't have. There was a 89 FMF on evilbay just the other day for $160. They do show up.
KC124
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6/7/2011
Location
Bates City, MO US
12/21/2021 12:56am

My 89's
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