If you’re struggling with the gearbox on your classic four-wheeler, you’re not alone. The Honda 1985 TRX 250 shifting issues are a common headache for owners of this otherwise reliable machine. This manual transmission can develop problems over decades of use, but most are fixable in your own garage with some patience and basic tools.
This guide will walk you through a logical troubleshooting process. We’ll start with the simple, no-tools checks and move step-by-step into more involved repairs. By the end, you’ll know exactly where to look and what to do to get your TRX shifting smoothly again.
Honda 1985 TRX 250 Shifting Issues
Before you start taking things apart, it’s crucial to understand how the system works. The shifting mechanism on your TRX 250 is a combination of your hand controls, cables, and the internal gear selector inside the engine. A problem in any one of these areas can cause missed shifts, a stuck gear, or a noisy transmission.
Initial Checks: The Easy Stuff First
Always begin here. These checks cost nothing and can save you hours of unnecessary work.
- Clutch Adjustment: A poorly adjusted clutch is the top cause of shifting grief. If the clutch isn’t fully disengaging, gears will grind. Find the adjustment points at the lever and near the engine case. Ensure you have the correct free play as per your manual.
- Shift Lever Position & Tightness: Is the shift lever loose on its shaft? A wobbly lever makes precise shifts impossible. Also, check that it hasn’t been bent and is hitting the engine case or footpeg, preventing full movement.
- Oil Level and Quality: Old, dirty, or low transmission oil is a major culprit. The gear selector mechanism inside bathes in this oil. Drain and refill with the correct type and quantity of oil—often 10W-30 or a quality ATV-specific motor oil. Metal flakes in the old oil are a bad sign.
- Shift Linkage Inspection: Follow the shift shaft from the lever into the engine case. Look for any obvious damage or bending. Sometimes the external return spring can break or come off.
Intermediate Troubleshooting: The Shift Mechanism
If the easy checks don’t solve it, the issue is likely in the external shift mechanism or the clutch itself.
Inspecting and Adjusting the Clutch
A clutch that’s worn or adjusted incorrectly will cause hard shifting and gear grinding. After checking cable adjustment, you might need to look inside the right-side engine cover.
- Drain the engine oil.
- Remove the right-side clutch cover.
- Inspect the clutch plates for wear or warping. Measure them against service limits.
- Check the clutch basket for notching where the plates sit. Deep notches prevent smooth movement.
- Look at the clutch push rod and ball for wear. Reassemble with proper adjustments.
External Shift Shaft and Pawl
Under the same clutch cover, you’ll find the shift mechanism. The shift shaft has a pawl or lever that engages the internal gear drum. This can wear out or become damaged.
- Check for excessive play in the shift shaft.
- Look at the tip of the pawl for rounding or chipping.
- Ensure the return spring is intact and providing good tension.
Advanced Diagnosis: Internal Transmission Problems
If everything external checks out, the problem lies inside the transmission. This requires splitting the engine cases, a significant job. Common internal Honda 1985 TRX 250 shifting issues include:
Worn or Bent Shift Forks
Shift forks slide the gears on their shafts. They can bend from forceful shifting or wear down at the tips. Worn forks won’t move gears fully, causing popping out of gear or failure to engage.
Worn Gear Dogs and Dog Holes
This is the most common internal cause of jumping out of gear. The “dogs” are tabs on the side of the gears that lock into holes on the adjacent gear. With age and abuse, these dogs and holes become rounded. The gear can’t lock solidly and kicks back out under load.
Damaged Shift Drum
The shift drum is a star-shaped cylinder with grooves that guide the shift forks. If the grooves wear or the drum itself gets damaged, the forks won’t move correctly, leading to incomplete shifts or getting stuck between gears.
Bent or Worn Shift Shaft
The internal part of the shift shaft can bend, or the pins that engage the drum can wear. This prevents the correct rotation of the shift drum when you move the lever.
Step-by-Step Repair Guide for Internal Issues
This is a major repair. Have a service manual, a clean workspace, and organize your parts.
- Engine Removal: Drain all fluids. Disconnect all cables, wiring, and the exhaust. Remove the engine from the frame.
- Case Splitting: Remove the cylinder head and cylinder. Flip the engine and remove all bolts from the crankcases. Use a case splitter tool or gently tap with a rubber mallet to seperate the halves. Never pry with a screwdriver at the sealing surface.
- Transmission Inspection: Once the cases are open, you can see the transmission shafts, gears, shift forks, and drum. Carefully inspect each part:
- Check shift forks for straightness and tip wear.
- Examine gear dogs and holes for rounding.
- Spin bearings for roughness.
- Look at the shift drum grooves for wear or scoring.
- Parts Replacement: Replace any worn components. It’s often wise to replace shift forks, the drum, and related gears as a set if one is worn. Match new parts to old for comparison.
- Reassembly: This is critical. Ensure all transmission gears are in their neutral positions. Use assembly lube. Make sure the shift drum pins align with the shift shaft mechanism. Carefully join the case halves, ensuring everything seats properly.
- Reinstallation and Testing: Reinstall the engine, refill with oil, and adjust the clutch. Test shifting with the engine off first, then carefully under low load.
Prevention Tips for Smooth Shifting
Keep your TRX shifting well for years to come with these habits.
- Change transmission oil regularly. Annual changes are a good minimum.
- Always use the clutch when shifting. Don’t force shifts under heavy load.
- Allow the machine to warm up before riding hard. Cold, thick oil makes shifting stiff.
- Keep the shift lever, linkage, and clutch cable properly adjusted and lubricated.
FAQ: Honda TRX 250 Transmission Problems
Why does my TRX 250 pop out of gear?
This is almost always caused by worn gear dogs and dog holes inside the transmission. The rounded edges can’t hold the gear in place under power. Bent shift forks can also be the cause.
What if my TRX won’t shift at all?
Start with the shift lever itself—is it loose or broken? Then, check the external shift shaft and pawl under the clutch cover. A broken return spring or severely damaged pawl can prevent any movement.
Why is shifting so stiff and hard?
First, check your clutch adjustment and oil. If those are good, the problem could be a bent shift shaft, worn shift drum grooves, or dry/damaged bearings supporting the transmission shafts.
Can I still get parts for a 1985 TRX 250?
Yes, many parts are still available from Honda as OEM, and there’s a healthy aftermarket. Common wear items like shift shafts, forks, and even gears can be found from online retailers specializing in vintage ATV parts.
My TRX shifts fine when off but grinds when running?
This points directly to a clutch problem. The clutch is not fully disengaging, so the gears are still spinning when you try to mesh them. Adjust, rebuild, or replace the clutch components.
Is it worth fixing the transmission on such an old ATV?
That depends on the machine’s overall condition and it’s value to you. The TRX 250 is a classic and reliable workhorse. If the frame and engine are sound, a transmission repair can give it many more years of service, often more cost-effectively than buying a new machine.
Fixing Honda 1985 TRX 250 shifting issues can be a straightforward adjustment or a deep engine rebuild. The key is to follow a systematic process. Start simple, work your way in, and don’t overlook the basics like oil and clutch adjustment. With some mechanical sympathy and careful work, you can restore that crisp, positive shift feel and enjoy your classic Honda for many more rides.