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Author Topic: RM125 Rebuild  (Read 19398 times)

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Offline TMKIWI

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RM125 Rebuild
« on: February 08, 2012, 06:11:03 AM »


I have started the rebuild on my 1984-85 RM125. I have 1 bike complete (above) and 1 spare frame (below).

Plus about 6 sets of plastics.
I have also bought this 84' which I pick up on sunday.

The plan is to build 2 complete bikes and have a spare bottom end.
The rebuild will take a couple of months as I am in no rush and the vmx season is just about over.
I pulled the 2 motor's apart yesterday and the 85' engine is in pretty good nick.

The bore is in good condition so I just need a piston & rod kit for the top end.
The clutch basket & hub are good as well as are the plates. So don't need to replace any of them. :)
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline TMKIWI

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RM125 Rebuild
« Reply #1 on: February 08, 2012, 06:22:16 AM »
The tranny is all good but I will replace all the bearings and seals anyway.



The motor will get a full rebuild of all bearings and seals.
Don't want to have to do it again in a hurry.
The 86' motor is in similar condition except a couple of gears have lost a bit of hardning.
The only main problem with both engines is the gear shift shaft looks like this.

Which I will have to straighten and build up with a bit of welding.
Both frames are pretty good with 1 missing only 1 side cover bracket and the other only 1 small crack on the rail under the engine.
I will get these sand blasted next week and decide which is best. I will wait untill I get the 84' to decide which 2 frame's to use.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline TMKIWI

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RM125 Rebuild
« Reply #2 on: February 08, 2012, 06:37:46 AM »
The rest of the frame is as to be expected.
New swingarm bushes, wheel bearings, steering bearings etc.
Will replace the lot.
Suzuki's Full Floater system. ;D

The shock will get a full rebuild with seals piston bladder the works.

The forks are getting the same treatment as well.
Have to order a few parts from yankee land so will update soon.
The strip down.


« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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RM125 Rebuild
« Reply #3 on: February 08, 2012, 12:28:33 PM »
They should look nice when your done  :) Almost as nice as that TM  ;D
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline SachsGS

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RM125 Rebuild
« Reply #4 on: February 08, 2012, 03:44:12 PM »
The Fullfloater was the plushest rear suspension ever.

I once bought 7 RM125s of that era COMPLETELY disassembled and in boxes. After awhile I was assembling the @#$% things in my sleep! The motors have zero bottom end but are nice bikes. ;D
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline TMKIWI

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RM125 Rebuild
« Reply #5 on: February 08, 2012, 07:02:46 PM »
Sachs. The only thing I am having problems finding are the linkage arm bearings.
No body does them that I have found.
All-Balls do the shock bearings but they are a different size.
I don't want to pay OEM prices.
Ideas ?
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline dbf498

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RM125 Rebuild
« Reply #6 on: February 08, 2012, 08:23:54 PM »
If you know bearing dimensions or bearing p/n give these guys a try: http://www.vxb.com/Merchant2/merchant.mvc. These bearings are made in China so take it for what it's worth. I'd use them as a last resort.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline TMKIWI

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RM125 Rebuild
« Reply #7 on: February 09, 2012, 07:01:00 AM »
The linkage bearings are a different size then used in most feilds.
I can get sizes close but not close enough.
They are not to bad actually so if I can't find any I will use what I have.
They are not actually bearings as such, more a spherical rod end.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline dbf498

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RM125 Rebuild
« Reply #8 on: February 09, 2012, 07:33:38 AM »
Oh yea...a spherical bearing.  Yea...that may be a little difficult to source. I got this picture from Motosport.com but Service Honda also has the very same drawing.

« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline SachsGS

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« Reply #9 on: February 09, 2012, 03:51:22 PM »
Suzuki had the nasty habit of custom manufacturing bearings to odd dimensions so that that they could not be sourced at bearing dealerships and were, as a result, very expensive. You can imagine my relief when I started riding Euro bikes again and every bearing was readily available.

If you still have your lathe you could machine sleeves to adapt the odd O.D. of the existing bearing to an off the shelf generic bearing - usually you can match the width and I.D..

When I raced an RMX I remanufactured the whole bike to get around this issue.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline TMKIWI

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« Reply #10 on: February 09, 2012, 07:03:05 PM »
Quote from: SachsGS on February 09, 2012, 11:51:22 PM
If you still have your lathe you could machine sleeves to adapt the odd O.D. of the existing bearing to an off the shelf generic bearing - usually you can match the width and I.D..

Yep. Thats what I will end up doing.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline ford832

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RM125 Rebuild
« Reply #11 on: February 10, 2012, 10:45:34 AM »
Cool project TMKIWI.Nice to see you getting a good bike  :P
The bearing thing always P'd me of on any of my jap bikes.So close to standard sizes but not quite.You know that is entirely intentional.I loved my KTM's and Berg for that reason-readily available,good quality aftermarket bearings at low prices in comparison to stock jap bearing pricing.
Like Sachs said,Suzuki's full floater system is still regarded as one of the best rear suspension systems ever built. 8)
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline TMKIWI

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RM125 Rebuild
« Reply #12 on: February 11, 2012, 04:06:33 AM »
Picked up the 84' today and I am very happy. ;D
Looks like the bike has sat in a shed for the last 20 years.
It is not a minter cosmetically but is all there and mechanically it is great.
It still has original plastics with the factory warning stickers.
It still has the original alloy bolts for the plastics and also the original fork guards.
The suspension linkage bearings are all good, just need a clean and re-grease.
It still has an original undented exhaust as well.
The cylinder is mint and the piston could go another round but will replace anyway.
The bore is only .025" over so has plenty of life. My other cylinder is 2mm over so will need resleeving if something goes wrong.
The frame has no cracks so this bike will be a pisser to get going.
I'll sand blast and paint the frame , Go over the gearbox while motor is out and throw it back together when I get my new suspension.





« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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RM125 Rebuild
« Reply #13 on: February 11, 2012, 04:10:03 AM »
If you don't mind me asking, how much did you pay for that 84?
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline TMKIWI

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« Reply #14 on: February 11, 2012, 09:08:23 AM »
 :-X
Not much.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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