In Progress
Lemon Bomber
This sweetheart of a 1975 TC100 is getting a refresh, a full electrical revitalization, and will become Yellow Bomber’s little sister.
SuzukiTC100
History
No clear history on who originally owned this bike, but it eventually made its way to a good buddy of mine. I had given him a Yamaha QT50 to go along with one he already had so him and his partner could go ripping around together. With a growing pile of projects — something I’m clearly on the verge of myself — he passed this one along to me. The bike is fully complete, minus a signal light. The tank doesn’t have a single speck of rust, if you can believe it. There’s some suspicious oil wetness that could point to a crank seal, but I’m hoping it’s just oil from the reservoir or pump — that’ll be investigated. It’s got very low mileage (I’ll update that once I actually look again), and the seat is in great shape too. I’m looking forward to getting this project underway. My partner has already shown a lot of interest in learning to ride on it, so that’ll make this one even more fun
Project details
We’re officially past the investigation stage and properly into the rebuild on the Lemon Bomber. What began as a plan to bring this little bike back to life has turned into a genuine mechanical resurrection. The initial no-spark issue was tracked down pretty quickly—the plug wire at the coil was basically headless Nick. A bit of a mad scientist repair later, and surprisingly… it worked. After cleaning and properly setting the points, I now have healthy spark. Both the ignition and kill switch are confirmed working. The carburetor (Mikuni VM20) was an absolute mess when opened up—somehow there was water sitting in the float bowl despite the tank being completely mint inside (zero rust, which is a huge win). The carb was fully torn down, cleaned, and run through the ultrasonic cleaner. All passages are now clear and usable, the floats checked out, and it was enough to get the bike to start and idle. Compression, however, told the real story. With oil added to the cylinder, compression comes up, but without it it drops off badly—classic signs pointing toward rings and/or cylinder wear. A new piston and rings are now in hand, and the top end comes apart next to determine whether a hone will be enough (looking promising so far) or if more machine work is needed. Big progress has also happened on the electrical side. The stator has now been sorted. The charging coil shares a tap with the ignition coil, so I left both circuits untouched to preserve proper ignition function. The lighting coil, however, was successfully isolated from ground, and I ran two new 16 AWG leads from it (in loom) for a 12V rectifier/regulator that will power the new 12V system. That keeps the ignition essentially original while creating a dedicated charging source for upgraded lighting. Mechanical progress has moved ahead as well: * All left-side seals have now been replaced * Oil pump was removed, cleaned, inspected, and fitted with a new gasket * Front sprocket was found with broken teeth and is being replaced along with chain and rear sprocket * Clutch plates were found badly aged, and since the basket has to come off for the crank seal anyway, new clutch components and the proper clutch tool are on the way * One exhaust stud broke during teardown, so those are being replaced as well A few earlier problems have also been dealt with: * Shifter lever is snapped at the splined clamp — still planning a repair or replacement * Throttle cable was completely seized after 20+ years sitting — now freed up and working properly Next steps: * Pull the cylinder and assess the bore * Hone and fit new piston/rings if measurements support it * Replace the crank seal behind the clutch basket * Install new clutch plates * Finish the 12V charging/lighting conversion * Replace points, condenser, and ignition coil to make the ignition fully reliable At this point, this has gone well beyond a revival. It’s being rebuilt. More updates as progress is made 🔧
Sections
Carb
The Lemon Bomber is running a Mikuni VM20 carb. Current jetting is a 200 main and a 22.5 pilot, which appear to be stock or very close to it. When I first tore into it, the carb…
Spark!
After digging into the ignition system, the points were cleaned up and properly set, which brought spark back to life. Good news—the “mad scientist” repair on the original ignit…
Compression
Compression is… less than ideal. Best reading so far is about 90 psi, and that’s with a bit of oil added to the cylinder. Without it, compression drops off quickly to around 50 …
Stator charging coil isolation
The lighting coil shares a tap with the ignition coil, so I left both circuits untouched to preserve proper ignition function. The charging coil, however, was successfully isola…
Shifting
As noted early on, the shifter clamp was broken. On top of that, the shift shaft itself was slightly bent, and the splines were in rough shape. I went ahead and welded the shifter—…
The saga of the stuck exhaust stud.
One of the exhaust studs snapped off during disassembly. After soaking it in PB Blaster and applying heat, I tried again—but it snapped, leaving very little sticking out to work wi…
Piston and rings
As suspected, the piston rings were stuck. Replacing them was the right call—and with everything already apart, it made sense to install a new piston as well. The head cleaned u…
Sprockets and chain
Not much to say here. I was Gina replace the sprockets and chain anyways. But this drive sprocket was worth showing.
Project gallery
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Project info
Status: In Progress
Slug: lemon-bomber
Created: March 21, 2026
Last updated: April 19, 2026