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1981 RM125x FOR SALE

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Craig and Roger D

Craig Taylor & Roger DeCoster


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The RM125x 1981 was the original design of the 3 similar models spanning 1981 1982 and 1983. It was the only one to have case reed induction. Both other RM125’s had full reed induction.

The 1983 RM125D had yellow forks and adjustable rear suspension compression damping.


RM125 X 1981

RM125 Z 1982

RM125 D 1983

Reed Valve

Rear suspension push rods.

Front Forks.



Fixed Damping




Fixed Damping



Adjustable Damping


This is what a 1981 RM125x engine looks like, it has case reed induction as against 82 83 which had full reed induction therefore the cylinder and cases are different and not interchangeable with 82 83. Pictures supplied by Jason Ladson from Australia. Click on each picture to enlarge.

This is an 83 RM125D engine. As you can see the intake is different from the 81 engine shown above and so are the cases.
The clutch cover and water pump are interchangeable but that is all.
The cylinder head is also different.


Did you know that the airbox on the D model was enlarged to allow greater airflow. The way to tell is to look at the box from the carb hole side. The 81 RM125x and 1982 RM125d boxes are U shaped but the 1983 RM125d boxes are squared off across the top to make the center section of the box larger and allow greater air flow. All boxes fit all model years as the mountings and the physical size are the same.


Did you also know that the radiator is slightly different for the 1981 RM125x compared to the 1982 and 1983 RM125Z and D. They are all the same size and fit all years but the outlet at the top of the Z and D model is slightly angled to fit the Z and D cylinder head whereas the X model outlet points straight down to align with the X cylinder head outlet.

Most people think that the 3 RM125 1981 1982 and 1983 model years had the same frame but they were all slightly different. The 81 and 82 are interchangeable but the 83 RM25d had the bell crank pivot set 20mm rearwards. and a different swing arm. If you use an RM125x frame with an RM125d swing arm you will alter the Full Floater ratio. It will work but not as Suzuki intended.


RM125x z above. RM125d right.


Below are the three cranks from an X Z and D. The X is the first picture.
You can see that the holes are different sizes.
This affects the weight and engine characteristics.


Below is the Z crank with medium holes and medium weight.

RM125 z-Crank

Below is a crank from a 1983 D with the smallest holes and heaviest weight.

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