Posts
1636
Joined
5/9/2013
Location
Hyllykallio, FI
Edited Date/Time
10/16/2026 3:04am
So, this is my third '80s Honda CR125 build. The build actually started when I was going through my leftover parts from my previous builds back in 2024. Here's my previous builds just in case you missed those: 1986 CR125 the build that started it all & 1984 CR125 build
I had collected a quite large pile of spare parts for '80s CRs, and I soon discovered that a lot of them were for the 1985 model CR125.
The real challenge has been figuring out what I had, which parts would work together, and how to turn them into a complete 1985 CR125
The first thing I noticed was that the right-side engine case oil drain bolt threads were gone. I used a repair kit that comes with oversized drain bolts and a thread tap for them, and I was able to rescue the engine case. After that, the engine cases made a quick trip through the dishwasher 😎
After that, the case halves got new bearings and a satin-black paint job
After I got parts delivery from WMX Service the crankshaft was rebuilt by a professional and the engine cases were assembled with new seals, gaskets and dowel pins.
You have '84, '85 and '86 models? If you're going to go for stock, that's cool. It would be rad to see O-show, Lechien and Dymond replicas, too.
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
Yes I have 1984, 1985 and 1986 CR125 currently in possession 😁
I'm going for a more stock look with this one. It's going to be a bit of a mixture of parts from '-85 and '-86, so it's not going to be an OEM quality restoration either.
I tried to avoid buying an expensive aluminum clutch cover and challenge myself at the same time. The next project was a big challenge: I tried to rescue a very corroded magnesium clutch cover with 3D-printed tubes (which I designed myself) inside the coolant passages and a lot of epoxy.
The next task was to refurbish the cylinder and the cylinder head. Aluminum from the piston had seized onto the cylinder, so I honed it myself using a cheap honing yool from a local hardware store. The cylinder head refurbishment was done by a local engine machine shop ( https://moottorikoneistus.fi/ ). For the piston, I chose a Wössner +1.50 mm oversize piston, and V-Force was selected for the reed valve, which was installed along with a new intake boot.
After that, I decided to tackle rebuilding the rear shock, doing the entire job myself from start to finish. This specific shock is from my '86 model bike; I had replaced it with a WP shock, which left the original one unused. I replaced the bumper rubber, the seal head, and installed a powder-coated spring along with fresh oil. I'm pretty happy with how it turned out.
Sanding down the scratched swingarm until it was smooth was a massive chore. It's a shame I couldn't find any photos of the starting condition anymore. Naturally, I also installed new bearings and seals in the swingarm at the same time.
The next step was assembling the rear suspension linkage with new bearings, bushings, and seals.
I ran into major issues with the frame at first. The main frame I had turned out to be an '84 model, and even though the '85 engine cases look identical from the outside, they are significantly wider at the mounting points than the '84 cases. On top of that, the '85 swingarm was wider than the '84 version, so that didn't fit either. Luckily, I found an '86 frame from a local salvage yard for a decent price ( Kisakone ). I sandblasted this frame at my workplace and then painted it myself using the RAL 2002 shade instead of powder coating.
The front fork was also leftover parts from my '86 CR125 project, as I had replaced its original front end with the front forks from an '88 CR250. I changed the fork oil before installation, but I forgot to take any pictures. Additionally, I cleaned the triple clamps and installed them onto the frame with new steering stem bearings. I also managed to find gas tank damper rubbers in good condition on eBay.
Next, I mounted the engine and the swingarm into the frame. For the footpegs, I fitted a pair of slightly modified OEM Yamaha pegs that I got from a friend.
After installing the rear shock and the tires, I finally had a rolling chassis. The wheels are from the '86 model, which is why they are gold. The front wheel was just a temporary solution at this point. I also fitted the carburetor into place. The carb is a Keihin PJ clone made by ZSDTRP, since finding an original one in good condition for a reasonable price was nearly impossible. The electronics are also from the '86 model. They came with a spare parts engine I had, so they were conveniently available for this project.
The next problem I noticed was that the 1985 subframe didn't fit with the 1986 main frame. When using the '85 subframe, there was a gap of several centimeters between the carburetor and the airbox boot. Luckily, the motorcycle salvage yard where I got the '86 main frame also had the subframe from the same bike available. At the same time, I bought an '86 exhaust pipe for my bike because I realized the mounting tabs on the pipe I had in storage didn't line up with the '86 frame
After sourcing the '86 subframe, the biggest issues with the project were solved. Through M46parts, I got a CDI bracket, swingarm chain guides, the plastic air filter cage and shock resorvoir mounting piece for my bike. Additionally, I installed a UFO rear shock mudguard and '86-style 'Pro-Link' decals
Next, I installed aftermarket GPI radiators along with a set of new aftermarket coolant hoses
Damn dude, you are a busy man!
I've been working on this project since January 7, 2024, mostly in the evenings after the kids have gone to bed. I've only just found the time to start documenting the build here on VitalMX, so the updates might make it look like the project has progressed faster than it actually has. 😄 It's been a slow, long-term project, one small step at a time.
Pit Row
I did a leak test on the magnesium clutch cover I had repaired, but to my disappointment, I noticed that coolant was still seeping through a small hole in the water pump area. By chance, I was offered the opportunity to buy a lot of '86 engine parts, which included an aluminum clutch cover that solved the problem. However, I still plan to go back to that magnesium cover one day and try to patch the leak, because I’ve already put so much work into it.
The next challenge was the aftermarket rear brake shoes, which were too thick to fit into place. I had to sand down material from the frame of the brake shoes until they finally fit. Additionally, I installed a new aluminum rear sprocket while the rear wheel was off.
Fitting the new UFO rear fender was a bit of an easier job. I drilled the mounting holes so that it sat straight, even though the subframe mounts had taken a bit of a beating over the years. I also installed the seat and the gas tank on my Honda to make sure the rear fender would line up correctly with them. Unfortunately, I didn't have any pictures left of the process of reupholstering the seat with an '86 model seat cover.
For the handlebars, I chose the almost legendary Renthal 971 bend in gold, which I think goes really well with the gold '86 wheels.
I also wanted to keep a functional ATAC valve on my bike, since I had all the necessary parts to install it and the stock exhaust pipe works best with it. At the same time, I installed clear tubing for the radiator overflow hose
Next up was refreshing the gas tank and the radiator shrouds. At first, I tried to sand and polish the gas tank, but it turned out to be too tedious of a task, so I bought a graphics kit that completely covered both the tank and the shrouds. I think the final result looked pretty good. At the same time, I also installed a new petcock on the gas tank
Nice work, man! 😍
A friend of mine had the same issue; he repaired the clutch cover, but the coolant leaks kept coming back... so he ended up buying an aluminum one from Russell, and everything’s been fine since!
I repaired the original shift lever using a KTM shift lever rebuild kit that I found on AliExpress.
I took the bike outside to get some better photos. Before taking the pictures, I had also installed a new UFO front number plate into place. The bike looked really good in the Finnish midnight sun
One of the mounting tabs on the exhaust pipe I had bought was broken off. I took a good tab from another completely dented exhaust pipe and welded it into place, after which I painted the pipe with high-temperature paint.
The next project was fitting the exhaust pipe into place. The mid-pipe was from some other bike model, so I had to shorten it a bit to get the silencer installed (which was a leftover spare from my '86 Honda after I upgraded it with a new DEP silencer). I didn't have a bracket for the silencer, so I fabricated one myself out of aluminum sheet metal.
The first start of the bike!
Then it was time to replace the temporary front wheel with a proper '86 model front wheel. Before mounting the tire, I tightened the spokes and cleaned the wheel as well as I could. After that, I installed a Michelin UHD inner tube and a slightly used tire I found in my storage. On AliExpress, I found a wheel spacer kit meant for XR models, which also fit the old CR's front wheel perfectly. Finally, I installed the front fender.
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