"Whitey" my 83 ATC 70 3 wheeler project.

Tripod said:
Recommend you test fire the engine with a drill and wratchet head. Pull starting is the absolute worst on an unknown engine.
Click to expand...
That may not be a bad idea. I’ve gone through the engine pretty thoroughly, compression is strong, no rust in the cylinder (checked with a borescope), no valve buildup, and both ports held WD-40 on top of the valves for over 24 hours. I converted it from a manual clutch to semi-auto using spare hard parts I had from a donor engine along with a brand new heavy-duty TB Parts clutch. It’s also running a new Nibbi carb and a complete new stator plate with all new electronics. Hopefully it should be a good little engine, but a test fire would definitely help confirm everything before final assembly.

Here are some pics of the engine as it went through its build:
SSR 125 (1).jpeg SSR 125 (2).jpeg 125 Clutch.jpeg 125 Clutch (8).jpeg 125 Clutch (1).jpeg 125 Clutch (7).jpeg 125 Painted (1).jpeg 125 Covers Painted (1).jpeg 125 Black (1).jpeg 125 Black (2).jpeg

Carlo C.
 
Guys,
I’ve been trying to track down a few top-end gaskets I needed to button this engine up, and it turned into more of a chore than expected. I now have about three sets of gaskets that won’t work on this engine, but they will fit all my other pit bike stuff so they’ll get used eventually.
After doing a lot of research, I finally figured out what I have. The engine is an older LIFAN 154FMI that came on SSR and other dirt bikes, not a pit bike. The difference between this 125 and the other 125s I’ve dealt with is that this was Lifan’s Heavy Duty / High Output version.

This engine has several differences:
  • 7mm head studs instead of the normal 6mm
  • Larger intake and exhaust ports
  • Larger valves
  • 12mm spark plug
  • Larger cylinder head cap
  • Larger right-side cam cover
Because of these differences, the standard 125 pit bike gasket kits just don’t fit this engine correctly. To solve the problem, I ordered some gasket material from NAPA, traced out what I needed, and cut them during my lunch break. I dug out my hole punch set, made the bolt holes, and they came out perfect. None of the usual companies I contacted had anything that would work. Honestly, I should have just made them from the start. It only took about 10 minutes, and the gaskets look just as good as or better than the factory pieces.

One more piece of the puzzle done.
Engine is finally finished.

125 F.jpeg 125 F2.jpeg
 
Guys,
Here is the info I got on the engine for those that are interested I actually learned a good bit:

Lifan​

Engine code breakdown
  • 1 = Single-cylinder
  • 54 = ~54 mm bore class
  • F = Four-stroke
  • M = Motorcycle engine
  • I = Vertical, air-cooled, OHC

154FMI = Vertical, air-cooled, SOHC 125cc-class engine


Core Specifications

  • Displacement: ~124–125 cc
  • Bore × Stroke: 54.0 mm × 54.0 mm
  • Engine type: Single-cylinder, 4-stroke
  • Cooling: Air-cooled
  • Cylinder orientation: Vertical
  • Valve train: SOHC, 2 valves
  • Cam drive: Chain-driven

Cylinder Head & Valvetrain
  • Head studs:
    • Typical: 6 mm
    • This engine: 7 mm (trail / heavy-duty version)
  • Spark plug:
    • Pit bike: CR7HSA (10 mm)
    • This engine: NGK DR8ES-L (12 mm, long reach)
  • Valve sizes (typical):
    • Intake ~27 mm
    • Exhaust ~23 mm

Induction
  • Carb mount: Spigot
  • Typical carb size: 22–26 mm
  • Large intake port confirms non-pit-bike head

Bottom End
  • Crankshaft: Pressed steel
  • Main bearings: Ball
  • Oil system: Wet sump, splash + pump
  • Oil capacity: ~0.9–1.1 L

Transmission / Clutch
  • Transmission: Typically 4-speed
  • Clutch types: Manual or semi-auto (same cases)
  • Clutch: Multi-plate wet
  • Manual ↔ semi-auto interchangeable

Ignition & Electrical
  • Ignition: CDI
  • Stator: 5- or 6-pole (year dependent)
  • Starting: Kick start standard, electric start optional

IMPORTANT: Why Pit-Bike Gaskets Don’t Fit

Although stamped 154FMI, this engine is NOT a pit bike version.

Confirmed features
  • ✔ 7 mm head studs
  • ✔ 12 mm DR8ES-L spark plug
  • ✔ Large valve cover bolt pattern
  • ✔ Large clutch-side cam bearing cover
  • ✔ Large intake port

Identification
  • Early trail-bike 154FMI variant (mid-2000s)
  • Used by SSR, Lifan, Zongshen
  • Found in full-size SSR 125 dirt bikes, not minis

Result
  • Standard “125 pit bike” gasket kits will not fit
  • Valve cover, head cap, cam bearing cover, and intake gaskets are all larger

​

 
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Guys,
I was out of town all weekend and didn’t get a chance to work on the little 3-wheeler, but I did have a couple of parts waiting when I got home. The washer and rubber cover for the clutch side showed up, and I couldn’t wait to install them. It’s one of those small details the original engines had, and I think it really adds to the look of this little bike.
125 Rubber Cover.jpeg

I finally pulled the trigger on some billet pieces I couldn’t stop looking at, and in my opinion they’re going to take this little bike to the next level. A billet front wheel hub with matching spacers is on the way, along with a pair of billet splined hubs for the rear wheels and billet axle covers for the rear axle. This is the kind of hardware that doesn’t just clean things up it flat-out transforms the look and gives the whole build that proper resto-rod attitude.

Front Hub (2).jpg Rear Hubs (2).jpg Axle Covers (2).jpg Axle Nuts & Washers.jpg

Hopefully I will get a bunch done this week and get everything off to painter and powder coater and then I can start the waiting process.

Carlo C.
 
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Guys,
I was hard at tearing the bike down for powder coat and paint when I decided to pump the brakes and bolt the 125 in first to see what I really had. Threw together a bare-bones wiring harness to get spark, set the tank back on, and ran a fresh fuel line with a filter just to see if the old girl would light.
She didn’t disappoint. Fired right up and sounded healthy. I didn’t run it long without an exhaust, but I had to hear it come to life before it all comes back apart.

Always a good day in the shop when one cranks up on the first try.
125 (1st Start)
 
Last edited:
Guys,
This is the boring middle stage of a build where everything’s apart, but it also means big progress is happening. The tank goes to the painter in the morning, the frame, forks, and misc parts head to the powder coater tomorrow, and the billet pieces are shipping out today to get anodized. A lot of good stuff in motion.

While everything’s out getting dressed up, I’ll be ordering the rest of the parts and cleaning and prepping everything so reassembly goes smooth and fast when it all comes back. The payoff is coming, and it should be worth the wait.
 

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Guys,

I was going to wait until the project was finished before showing some of the personal touches I’m adding to this little 3-wheeler, but I figured I’d share a bit of what’s going on. I’ve built a lot of the small Honda bikes over the years and I always try to respect the year and the original look so I don’t take away from what they are. This one has gone a little further than I originally planned, but I still think it’ll be recognizable when it’s done, just a little more modern and a little more adult-friendly. I decided I wanted to add a headlight, but it had to look factory. I dug through my parts bin and found an old steel Z50 headlight bucket I had left over. I ordered a new glass lens and trim ring for it and once I mocked it up to the forks, it just looked right. The size fits the bike perfectly.
To mount it properly, I got in touch with Josh Norton and had him make me a set of his headlight ears that I could weld to the forks. Josh does a great job making hard-to-find replacement parts for the older Hondas, and these look like they belong there.
When I blasted the replacement forks I bought off eBay, I found more than I expected. The front axle holes were egg-shaped from someone running the axle loose at some point. They were worse than they looked under the old paint.

Fork Hole (1).JPG Fork Hole (2).JPG
So I welded the holes up, took my time, and brought them back round the way they should have been from the start. It was more work than the forks were probably worth, but I wasn’t about to bolt something questionable under this build. Once that was handled, I welded the new headlight ears on and mocked everything up.

Fork (1).jpeg Fork (2).jpeg
Now they’re solid, straight, and honestly one of the cooler parts of the build. It’s little details like this that most people won’t notice, but I think they make all the difference. Hopefully next week I’ll start getting parts back from powder coat and paint so I can finally begin putting this thing together for good.
 
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