1989 Yamaha TZR250 2MA Mikuni TM28SS Carb Cleaning & Exhaust Silencer Repacking | Ep 7

Welcome back to Episode 7 of our 1989 Yamaha TZR250 restoration diary! Before taking on this project, the most mechanical work I’d ever done was changing the engine oil. In this episode, we tackle two essential sub-assemblies on the workbench: cleaning the twin Mikuni TM28SS flat-slide carburettors and completely repacking the alloy exhaust silencer cans. First, we get the carburettors set up on the bench for a methodical strip-down. We inspect the brassware, check the #230 main jets and #25 pilot jets, verify the 5L19 needle clip position, and ensure the float heights and delicate internal fuel passages are completely clear. From there, the spanners give way to some physical bench work: drilling out the old rivets on the aftermarket alloy silencers, extracting the saturated, oily packing, cleaning the perforated internal core tubes, and wrapping fresh high-density 2-stroke exhaust matting before sealing them up with closed-end rivets.[ No rush, no fake drama—just methodical bench work accompanied by some raw garage blues.[cite: 1, 2] Drop your carburettor tuning advice and thoughts in the comments below! -------------------------------------------------------------------------------- 🛠️ THE BIKE & SETUP SPECS: • Model: 1989 Yamaha TZR250 (2MA Chassis / 1KT Bodywork Hybrid) • Carburettors: Twin Mikuni TM28SS Flat-Slide • Jetting Baseline: #230 Main, #25 Pilot, 5L19 Needle, 15.5–16.0mm Float Height • Exhaust: Martin Johnson Period Expansion Chambers with Repacked Alloy Cans -------------------------------------------------------------------------------- ⏱️ CHAPTER TIMESTAMPS: 00:00 - Garage Catch-Up & The Bench Plan 00:20 - Stripping the Mikuni TM28SS Flat-Slide Carbs 07:53 - Whats that box? 08.30 - Carb Assembly 14:45 - Drilling Out the Silencer Rivets 20:35 - De-Coking the Perforated Core Tubes 22:00 - Wrapping Fresh Matting & Riveting with Closed-End Rivets 26:15 - Next Steps #TZR250 #Yamaha2Stroke #MotorcycleRestoration #2Stroke #MikuniCarbs #ExhaustRepack #GarageBuild #DIYMechanic #WorkshopBlues