1980 RM125 Project

There is another guy who is just finishing a 1980 rm 125 project on thumpertalk under " Suzuki 2-strokes". He will have much help for you on this I am sure.

Those bikes look really good. Run pretty good too! My brother had a nice one stolen in Dallas a few years back with a few trick bits on it. F'n thieves....

I am curious, where did u get it? I recently sold one similar to it

I was pretty impressed with OEM parts availability on the 77 RM125 when I was hunting parts. None of those available new?

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As stated above by my brother you will be surprised how many parts are available. You can find numerous parts lookups on the inter-web to get you going, but unfortunately your brake torque rod and chain guide parts aren't available but I do have some suggestions.

Google Alpha-Sports. They have an awesome Suzuki parts lookup.
(*The link sniffer is not allowing me to post the actual url)

Also, if you haven't checked out Mark's Swapmeet page you need to. A great resource and I recommend just posting a wanted ad for the things you need if you don't buy new.

Again, Google Marks Swapmeet.

Suggestions and how my previous 1980 RM125 was set up. I found an aluminum brake torque rod in a bone yard that probably came off a mid to late 1980's YZ model. Find one that matches the length or is very close. They are out there! As for the chain guide I bought a Fredette Racing model for a late 90's model RM125. A little shimming and some minor grinding and it fit nicely. It was anodized blue to top it off. I can't remember the correct year model though so you may have to just watch that auction site for a used one. The suspension setup I ran was 16.5 inch Works Performance shocks and I used a 43mm 1984 RM model front end with Race Tech springs. As for the motor I had to correct the horribly matched intake ports from the reed valve. If you're good with a Dremel you can do this yourself. I had a struggle with getting the carb setup for some reason. I used new carbs, old rebuilt carbs, carbs off other running bikes, and nothing worked well. I found a NOS 1983 RM125 carb and it ran perfect. Set it up to stock specs with a slightly larger main jet. I ran a DG head, Jemco exhaust, digital PVL ignition, and all the ports were cleaned up. I even modified the petcock as the diameter is super small and it just doesn't flow enough gas when the bike is wound out.

I'm still pissed about it being stolen...it was a nice bike.

You can message me if you want. I have a box of parts somewhere in my attic that I could part with.

I love that bike! Hopefully you got a good deal on it. When I was looking for a 125 up in the northeast, they were a little scarce for reasonable pricing. The good ones got bought same day off of CL.

Anyway, it looks like you could bolt a solid block of nylon or HDPE into that chain guide and be on your way. Obviously Lonestar's retrofit idea will take more time and effort, but potentially way better looking outcome, maybe work better too.

On my 1982 RM125, the silencer was blown out hollow. I cut the back end off and packed it with insulation and machined an aluminum cap to slip-fit into the end and bolted it on. Worked great. Answer, FMF, etc... silencers are getting expensive on ebay!

And what's up with the full-floating rear brake rod? If it's loose, you can get bronze bushings at Aubuchon Hardware to tighten it up. Drill to fit and install.

Those are all perfect period style fixes. Nice work!

About the forks: Old skool tuning in my shop goes like this: I usually fill to spec with ATF. Knowing that I will need more oil than stock and probably higher viscosity, I usually add heavier oil on top. Suzuki actually suggests this method in their GS models. Add 10-W40 to raise and thicken the oil and you can get some pretty good action out of the old boingers. This method will get you on the track while you're saving up for emulators. (you might want to install a crossbar pad though!)

Let me try to upload a photo of fork oil viscosity chart for ya in case you're interested....

Holy crap it worked LMAO! this is a good chart to use for comparison.

Mobil 1 ATF is right in the middle of the chart. It's about 12 weight.

Gotta LOVE the cheng-shin meats too.

I bought one of these back in the day, a dealer was closing and got it below cost. It was very decent, nothing outstanding about it though.
Jay (?) do you still have the 96? Your thread on tt was a very inspiring build for me,a spraybomb special to solid runner! Ive done 4 builds like that one but none of them were in worse shape...but close!

Good luck on your parts sourcing.

I raced the "N" and the "T" models, loved them. Here is my '80 "T" model.

I love that white RM and really like the fender/plates. Apparently I'm the only one that liked the fender design. What shocks are those?

Thanks, It was easier for my family to spot me on the track amid the sea of yellow bikes ! I really liked the M. Robert rear fender. "D.C." plastics makes a nice copy in all the colors. Those shocks were call " Motosport" air shocks. They had a 1" shaft and worked well for me. Troy Lee painted the tank for me!

I want to see a full picture of the little yellow Toyota pickup in the background too! That truck looks old skool cool. Interesting on the shocks. I never heard of Motosport air shocks. Any other tricks to the motor you can remember?

If I remember, a different ignition, major porting, scavenged works pipe ( from the US Suzuki dumpster) R&D air box with UNI weenie air filter, 36mm carb, & Trick Reeds... It was bloody fast !

The carb is a Mikuni VM32.... I went with heavier fork springs in the front with 10 wt. fork fluid, not oil & 16.5 inch Progressive suspension shocks on the rear, boyseen reads and left the motor stock so far on my racer....It's plenty fast stock .....I'm also building another 1980 RM125 that I'm installing 43mm forks w Race tech emulators, using 1984 rm125 clamps and Ohlins remote reservior shocks (16.5) and a (32mm or 34mm) flatside carb and modified cylinder, head and pipe (1/4 inch cut out of the mid section)....Parts are available, but I've bought 3 other RM's (1-1980 &2-1979) parts bikes..for super cheap.

That's how they run. No powervalve = power in only one area. I believe the 1980 RM125 was a piston port motor and had all it's power up top, at least the 81 liquid motor was like that. Another thing that would exaggerate this would be a worn out motor with low compression.

I remember the RM's always blowing through fiber disks. Maybe the riders were fanning the clutch all day long to stay on the pipe. Regardless, with an old skool 125, you're going to need an easy clutch pull.

It's a case reed motor and it's mostly on the top end screamer....The main jet should be a 250-270 range, make sure the float level is set...very finicky ....you can alter the ign to 5 degrees BTDC...seems to help....replace the stock petcock with a newer model (83-87) or similar year yz...more flow....make sure you have plenty on compression...or it will suck arse....I run the forks at 5mm up in the clamps

What's wrong with the plastics? You can sand / scrape the chalk and scars. Might be better than painting. I've brought back some very nasty plastic to look very nice. Takes some time though....

Case reed? Way ahead of it's time I guess huh! I do remember the piston port motors and when they changed to the cylinder reed in '82 the "punch" was missing...