What a CDI box does and why you might replace it

The CDI box (Capacitor Discharge Ignition) controls when your Rhino's spark plugs fire. It takes signals from the crankshaft sensor, processes them, and tells the ignition coil exactly when to spark. A failing CDI box causes hard starting, stalling at idle, cutting out under load, or no spark at all — symptoms that look like fuel or carb problems but actually live in the ignition system.

On a 2008 Rhino 700, the original CDI box is prone to failure after 8 to 12 years of use, especially if the machine has sat for long periods or been exposed to moisture. Replacing it is cheaper than chasing phantom fuel system problems, and a used OEM box costs significantly less than a new one.

Key Takeaways

  • The CDI box controls spark timing; a bad one causes hard starts, stalling, or complete no-start conditions that feel like fuel problems but are not.
  • Used OEM Yamaha CDI boxes for the 2008 Rhino 700 run $40 to $120 depending on condition and seller, versus $200+ for new.
  • The part number you need is 5Y1-85540-00-00 or 5Y1-85540-10-00; confirm it matches your specific model before buying.
  • Installation takes 15 to 30 minutes and requires only basic hand tools; the box bolts to the frame under the seat area.
  • Buy from salvage yards, eBay, Craigslist, or ATV-specific forums where you can verify the seller has tested the part or offers returns.

Finding the right part number for your 2008 Rhino 700

Yamaha made the Rhino 700 from 2008 to 2013 with minor revisions. The CDI box part number for the 2008 model is 5Y1-85540-00-00 or the later revision 5Y1-85540-10-00. Both work in your machine, though the -10-00 version is slightly more common in the used market because it was produced for longer.

Before you buy a used box, confirm the seller's part number matches one of these two. A box from a different year or model — even another Yamaha — will not work. Check the seller's photos or ask them to read the number stamped on the box itself. If they cannot or will not provide it, move to the next listing.

Where to find used CDI boxes in the USA

eBay Motors is the largest single source for used Rhino 700 CDI boxes. Search "Yamaha Rhino 700 CDI box" and filter by "Used" and your region to avoid shipping costs. Prices typically range $50 to $100, and most sellers offer returns if the part does not work. Read the seller's feedback score and look for mentions of testing or warranty in the listing.

Craigslist and Facebook Marketplace let you inspect the box in person before paying. Local pickup saves shipping and lets you ask the seller whether they tested it or removed it from a running machine. Prices are often lower than eBay — $40 to $80 — because there is no shipping or platform fee.

ATV salvage yards stock used Rhino parts and can tell you when ready whether a box is in stock and whether they test before selling. Call ahead; many yards will hold a part for 24 hours. Prices run $60 to $120 depending on the yard's location and markup.

ATV forums like Yamaha Rhino Forum and Rhino Central have classified sections where private sellers post used parts. These sellers are often experienced riders who know whether the part works. Prices are competitive, and you can ask technical questions before buying.

What to check before you buy a used CDI box

A used CDI box cannot be tested without installing it in a machine, so you are relying on the seller's honesty or the platform's return policy. Ask the seller directly: "Was this removed from a running machine?" or "Do you offer returns if it does not work?" If they say yes to the first question, that is a good sign. If they offer a return window of at least 7 to 14 days, you have recourse if the box is dead.

Inspect photos for corrosion, cracks, or water damage on the case. The connector pins should be clean and not bent. If the seller has photos of the box installed in a machine or removed from one, ask for those — they suggest the part was recently in use rather than sitting in storage for years.

Avoid boxes listed as "untested" or "sold as-is, no returns" unless the price is very low and you are comfortable with the risk. A $30 gamble is different from a $100 one.

Installing the new CDI box yourself

The CDI box on a 2008 Rhino 700 sits under the seat, mounted to the frame. Disconnect the negative battery terminal first to avoid accidental shorts. Remove the seat by unbolting it from the frame — usually two bolts. Locate the CDI box; it is a black rectangular module with a wiring harness plugged into the top.

Unplug the wiring harness by pressing the release tab and pulling straight out. Unbolt the CDI box from the frame — typically two bolts. Slide the new box into place, bolt it down, and plug the harness back in until you hear or feel it click. Reinstall the seat, reconnect the battery, and start the machine.

If the Rhino starts and runs normally, the box is good. If you still have no spark or hard starting, the problem is elsewhere — likely the crankshaft sensor, ignition coil, or wiring. Do not assume a second CDI box is the answer without testing those components first.

Cost comparison: used versus new CDI boxes

A new OEM Yamaha CDI box for the 2008 Rhino 700 costs $200 to $280 from a dealer, depending on location and current inventory. A used box in good condition runs $40 to $120. The savings are real, but the trade-off is that you cannot return a used part to a dealer if it fails — you rely on the seller's return policy or your own diagnosis skills.

Aftermarket CDI boxes designed to work in the Rhino exist but are rare and often unreliable. Stick to OEM Yamaha boxes, whether new or used. The cost difference between used and new is large enough to make a used box worth the small risk, especially if you buy from a seller with a return window.

What to do if the used CDI box does not work

If you install the used box and the Rhino still will not start or still stalls, do not when ready assume the box is bad. Check that the wiring harness is fully seated — a loose connection feels like a dead CDI box. Verify the battery is charged and the negative cable is tight. Start the machine with the kill switch in the "Run" position, not "Off."

If those checks pass and the machine still does not start, the box may be bad. Contact the seller and explain the problem. If they offered a return window, ship the box back and request a refund or replacement. Keep photos and notes of what you tried so you can explain the issue clearly. If the seller refuses to help, you have a claim with eBay, Craigslist, or your credit card company, depending on where you bought it.

Frequently Asked Questions

Can I use a CDI box from a different Yamaha model?

No. The CDI box is tuned to the specific engine and ignition system. A box from a Rhino 450, Grizzly, or other Yamaha will not work in your 2008 Rhino 700, even if it looks similar. Always confirm the part number matches 5Y1-85540-00-00 or 5Y1-85540-10-00.

How do I know if my CDI box is actually bad?

A bad CDI box usually causes no spark at all — the engine cranks but does not fire. You can test this with a spark plug tester ($10 to $20) or by removing a spark plug wire and grounding it near the engine while someone cranks it. If there is no spark, the CDI box is a likely culprit. Hard starting or stalling at idle can also point to it, but fuel and carb problems cause the same symptoms, so rule those out first.

Is it worth buying a used CDI box if I can afford a new one?

Yes, if the used box comes from a reliable seller with a return window. The risk is low and the savings are significant — $100 to $180. If the used box fails, you return it and buy new. If it works, you have saved money and learned the part was the problem.

Do I need any special tools to install a CDI box?

No. You need a basic socket set or wrench to remove the seat and unbolt the box, and a screwdriver may help with the battery terminal. The job takes 15 to 30 minutes and requires no special knowledge.

What if the seller shipped me the wrong part number?

Contact the seller when ready with photos of the part number on the box. If it does not match your machine, request a return and refund. Most eBay sellers will pay for return shipping if they sent the wrong item. If they refuse, open a case with eBay and provide the photos as evidence.