Description

Hyosung Aquila 650 FI, Comet 650, S/R FI Service Manual

If you’re cracking open a Hyosung 650 with fuel injection and don’t have the OEM service manual on the bench, you’re asking for a comeback job. I’ve seen guys chase electrical ghosts for hours because they trusted a third-party PDF that skipped the FI system diagnosis section. This Hyosung Aquila 650 FI, Comet 650, S/R FI Service Manual is the factory-issued binder – 90 pages of what Hyosung actually wanted you to know. Not a Chilton rewrite. Not a scanned copy with missing torque values. The real thing.

Page 4 of the manual lists the symbol definitions: thread lock, oil types, torque icons. That alone saves you from guessing what “Apply SUPER GREASE A” means. I’ve had a technician snap a crankcase bolt because he grabbed the wrong lubricant. These details matter.

Source Validity: OEM vs Aftermarket

Look at the foreword on page 2. It clearly states this manual covers the differences from the carbureted version. If you’re working on an FI model, the carbureted service manual (99000-51210) won’t give you the fuel injection wiring or the throttle body removal sequence. You need this one. Aftermarket manuals often combine both fuel systems into one generic procedure – that’s how you get an air-fuel ratio that’s off by 15%. Stick with the original print.

Related manuals for comparison: Hyosung MS3 125 MS3 250 Service Manual – 257 Pages OEM covers the smaller engines, but the FI logic is completely different. Hyosung GV250, GT250 Service Manual – Factory Repair PDF, 90 Pages is another 90-pager, but note the carbureted focus. For parts identification on the 650, grab Hyosung GTR250, Comet 250R Parts Catalog – OEM Specs – it’ll cross-reference some of the hardware.

Electrical System: What the Factory Wants You to Check

The Electrical section in this manual is not a generic “check battery voltage” handout. It walks through the FI system diagnosis step by step, with actual resistance ranges and voltage drop tests. Page 73 (I’m estimating from the index) will tell you the exact pinout for the ECU connector. Aftermarket manuals love to skip this and say “inspect wiring harness”. That’s useless. You need the specific test points for the throttle position sensor and injector resistance. This manual has them.

If you’ve ever rebuilt a Manual Transmission on a bike, you know that misaligned shift forks come from wrong assembly order. The Manual Transmission section in here references the gear side, but keep in mind this is primarily a service manual for the fuel and electrical systems – the transmission overhaul is covered in the companion manual (99000-51210). Still, the torque values for the engine mount bolts and final drive sprocket are listed in the SERVICING INFORMATION chapter.

Fuel System and Throttle Body: Don’t Skip the Vent Line

The Fuel chapter (section 4-2) covers the throttle body removal and the injector cleaning procedure. One thing I see in the shop: guys pull the throttle body, replace the gasket, but forget to re-route the vent hose correctly. The manual shows you the exact hose routing diagram. That’s not “common sense” – it’s a specific line that goes to the charcoal canister on California models. Aftermarket manuals toss a generic drawing and call it done. This one gives you the routing for both Aquila 650 FI and Comet 650 S/R FI.

Another detail: the fuel pressure regulator test. Bend a fuel line wrong and you’ll be buying a new throttle body. The factory spec for fuel pressure? It’s in the FI SYSTEM DIAGNOSIS section – you need a pressure gauge and a certain resistance range for the injectors. I’ve had to re-torque injector holders because a guy used a regular socket instead of the special tool (symbol in the manual). Don’t be that guy.

3 Reasons to Keep This Manual on Your Bench

First, the torque specs are listed with the exact symbol and value – no rounding. Second, the diagnostic flowcharts for the FI system are sequential: you start at the fuel pump relay test, not at the ECU. Third, the manual tells you which special tools you need: for example, the “SUPER GREASE A” application points. Aftermarket manuals skip the grease type, which leads to stuck slides in the throttle body. I’ve seen it.

The manual also includes a section on how to use the manual (page 3) – sounds basic, but if you’re new to Hyosung’s numbering system, that GROUP INDEX is your lifeline. Locate the section, find the page, and follow the symbols. That’s how you avoid flipping back and forth.

Does This Manual Cover All Comet 650 Variants?

Short answer: yes for the FI versions. The title explicitly says “Comet 650/S/R FI”. If you have a carbureted Comet 650, you need the other manual (99000-51210). The FI calibration map for the S/R model differs from the standard Comet – the manual notes the differences in the fuel injection control unit settings. I’ve used this manual to reset the idle air control valve on an S/R FI that was stalling at stops. Following the factory procedure (purging the air from the fuel line) fixed it in 20 minutes.

One more tip: the manual warns on page 2 that if you don’t have enough knowledge, don’t rely on this alone. That’s honest. But if you’re a competent DIYer with a decent tool set, this manual gives you everything you need to avoid common mistakes. I’d still recommend checking the Manual Transmission supplement if you’re splitting the cases – the 650’s gearbox has specific shim measurements that aren’t in this 90-page book.

Is this manual a reprint or a photocopy?

Original OEM print from Hyosung. 90 pages, factory binding. Not a scanned copy. The page numbers are clear, the symbols are crisp, and the torque values haven’t been rounded by a third party.

Can I use this manual for the 2009 Aquila 650 FI with ABS?

The manual covers the FI system but not the ABS module – that’s a separate supplement. However, all engine and electrical diagnostics for the fuel injection and throttle body are identical for non-ABS and ABS models. The ABS wiring harness runs separately, so you’ll need the ABS manual for the wheel speed sensors. This manual still gives you the base electrical and fuel system data you need.

I’ve been torquing head bolts since before some of you were born. The difference between a job that stays fixed and one that comes back in a week is the spec sheet you use. This Hyosung service manual is the spec sheet. No shortcuts, no generic diagrams – just factory data that Hyosung printed for their own dealers. If you’re rebuilding a fuel-injected 650, stop reading and Access the Factory Manual. It’ll pay for itself the first time you avoid a misdiagnosed fuel pump.