Hey all, I've been on the quest for an alternate 50cc 4-stroke engine complete w/electric start & internal gearbox for my next project and wouldn't ya know it - Crazyhorse is already all over it lol (no Red, I'm not thinkin' a choppa heh). build thread: http://motorbicycling.com/f40/xl-chopper-4-stroke-pit-dirtbike-18970.html engine: Loncin Engine - 110cc Dirt Bike - $139 SPECIAL 70cc Engine Complete - Full Auto - No Reverse - $139.00 - HighRpmRacer.com Still, finding just the right engine for your needs can be a bit of a challenge - while I've not found a vertical 50cc 4-stroke, I figured I'd post the list of what I've found with prices & distributors (although I dunno if they're trustworthy as I've not done business w/them yet ofc). So - if ya know of any 50cc 4-stroke engines w/internal gearboxes & electric/kickstart (horizontal, vertical, auto or otherwise) please do add to this list! Here's a link to Lifan - although they don't sell direct, it's a good place to get engine model numbers to search for. Lifan 1P39FMB double-automatic clutched electric starter/Kick starter 50cc $299.95 Compression ratio: 9.0:1 Displacement: 49.5cc 50cc Class Max. HP: 2.7 HP @ 7,500 RPM Max. Torque: 2.0 ftlbs @ 5,500 RPM Carburetor: 19mm Walbro or Sheng Wey Measurements: 17" x 10 1/4" x 8 1/4" LIFAN 50cc Electric - Engines - Lifan 50-150 Engines - LIFAN 50cc Electric - TBolt USA, LLC Hooper Imports Experts on Chinese Motorcycles and Parts, Engines - Product Detail Lifan 50CC Engine 50CC3A-T Electric Start $299.00 Engine Model Lifan 1P39FMB Type 4-Stroke single-cylinder OHC air cooled Compression ratio: 9.0:1 Displacement: 49.5cc 50cc Class Max. HP: 2.7 HP @ 7,500 RPM Max. Torque: 2.0 ftlbs @ 5,500 RPM Carburetor: 19mm Walbro or Sheng Wey LIFAN 50CC Engine - Engines - Lifan 50-150 Engines - LIFAN 50CC Engine - TBolt USA, LLC SSR 50cc Engine SSR-50-BRN Kick start $199.00 Displacement: 50cc Gears:4 speed ,1 down 3 up Carb:Mikuni 16mm Ignition:CDI Flywheel type SSR 50cc Engine - Engines - Thumpstar & SSR Engines - SSR 50cc Engine - TBolt USA, LLC ^ I'd call to confirm ...and thanks to Crazyhorse - we've now a list of links for examples of successful builds using this engine type: http://motorbicycling.com/f40/builds-fyi-clone-honda-4stroke-atv-25194.html Thanks man!