1990 Yamaha YFM250 MOTO-4 Steering Stem Bearing Replacement Guide
Shop parts for a 1990 Yamaha YFM250 MOTO-4 ATV.
Steering stem bushing replacement on the 1990 Yamaha YFM250 MOTO-4 is straightforward maintenance that restores play-free, precise handling and protects the frame’s steering housing from the damage that comes with a severely worn pivot. This guide covers the complete procedure from disassembly through the final check that confirms the job is done right.
Tools and Bushing Kit Selection
Having the right tools staged before starting saves time and prevents mid-job improvisation on the YFM250 MOTO-4. The core list: an ATV stand or floor jack and stands for safe front-end support, a complete socket set with drive extensions, a torque wrench, combination wrenches in the sizes for the YFM250 MOTO-4’s stem nut and tie rod hardware, a cotter pin removal tool, and a rubber mallet.
The YFM250 MOTO-4 uses a bushing at the steering post pivot—typically a bronze or composite sleeve that the post slides through. A bushing kit sized for this model includes the replacement bushing and associated seals. A bushing driver or socket sized to the bushing outer diameter seats it squarely without distorting the bore.
What a Worn Steering Stem Bushing Feels Like
Steering stem bushing wear on the YFM250 MOTO-4 shows up as a notchy or rough feeling during slow bar sweeps, a wandering or vague front end feel during loaded riding, and eventually detectable play at the post when tested with the front end elevated.
Physical play testing confirms wear severity on the YFM250 MOTO-4. With the front end lifted and the tires off the ground, grip the bars close to the stem and push and pull laterally—not turning the bars, but checking for the post to move within the bushing. Any detectable looseness indicates the bushing has worn beyond its service life. A helper watching the housing junction while you push and pull can make subtle movement visible that your hands might miss.
Understanding Steering Stem Bushing Wear on the YFM250 MOTO-4
Utility ATVs like the YFM250 MOTO-4 are typically worked harder and serviced less frequently than sport machines, which creates a wear environment where the steering stem bushing takes more accumulated stress between replacement intervals than the design alone would suggest. The combination of heavy front loads, towing forces that change the weight distribution and front-end loading, and constant low-speed turning on rough ground puts the bushing at the steering post frame pivot through a varied and demanding load cycle.
Water and grit intrusion are the factors most likely to shorten the YFM250 MOTO-4’s steering stem bushing service life beyond what the load environment alone would produce. Farm and ranch use means wet conditions, mud, and working in areas where the underside of the machine accumulates debris.
Disassembly: Getting the Stem Out of the Frame
Before starting disassembly on the YFM250 MOTO-4, note the original position of the handlebar clamps so the bars go back at the same angle and height. Remove the clamp bolts and move the bar assembly clear without disconnecting cables where possible. On utility ATVs with wider bars or significant accessory wiring at the handlebars, loosely tying the assembly to a nearby frame tube keeps it from pulling on cables during the rest of the disassembly.
Free the tie rods from the YFM250 MOTO-4’s steering arm at the base of the post: pull the cotter pins, unscrew the castle nuts, and release each tie rod taper from the steering arm using a proper puller rather than improvising. Utility machines with years of outdoor service may have the tie rod ends corroded into their tapers—penetrating oil applied before the job makes this step much easier.
Inspection and Removal of the Old Steering Bushing
Inspect the bushing and post shaft after removing the steering post from the YFM250 MOTO-4. On the YFM250 MOTO-4, wipe the old grease from the bushing and post shaft and look at the contact surfaces. A bushing worn oval or egg-shaped rather than remaining round allows the post to rock and produces the play felt at the handlebars. Scoring or grooving on the bushing bore from contaminated lubricant indicates the bushing has been running with grit in the contact zone.
Drive the old bushing from the YFM250 MOTO-4’s housing bore using a driver or socket sized to the bushing outer diameter. Work from one end and keep the driver centered to drive it out evenly. Once removed, clean the bore with contact cleaner and inspect the bore surface for scoring, roughness, or ovality from a bushing that was spinning in the bore rather than staying fixed.
Pressing In the New Bushing and Reinstalling the Stem
Installing the new bushing correctly is the step where having the right driver makes the biggest difference on the YFM250 MOTO-4. Drive the new bushing into the YFM250 MOTO-4’s housing bore using a driver or socket sized to the bushing outer diameter. The driver must contact the full face of the bushing so it enters the bore straight rather than tilting. Start the bushing by hand to confirm alignment before applying driving force.
Guide the steering post of the YFM250 MOTO-4 back into the housing from above, seating it into the freshly installed bushing. The post should enter the bushing with light, smooth resistance—not sloppy, not binding. If the post binds before it seats fully, confirm the bushing went in straight; a cocked bushing reduces the effective bore diameter and causes exactly this symptom.
Final Reassembly and Steering Verification
With the post reinstalled in the YFM250 MOTO-4’s frame, snug the stem retaining nut incrementally while testing steering feel at each step. No play and no binding is the target; the bars should sweep smoothly from stop to stop with light, consistent resistance and no tendency to stick or index at any position. Secure the nut with the appropriate retention hardware and reinstall the handlebar assembly at its original position.
Reconnect both tie rod ends at the YFM250 MOTO-4’s steering arm, torque the castle nuts, and install new cotter pins—not the originals. Lower the machine, walk it forward, and do the final steering sweep by hand. The feel should be markedly better than the worn bushing you removed: smooth, direct, and play-free from stop to stop.
Related Shopping Categories
Shop Steering Head Bearing Kits for a 1990 Yamaha YFM250 MOTO-4 ATV.
Shop Tie Rod Ends for a 1990 Yamaha YFM250 MOTO-4 ATV.
Shop Steering Stems for a 1990 Yamaha YFM250 MOTO-4 ATV.
Shop Grease for a 1990 Yamaha YFM250 MOTO-4 ATV.
Shop Wheel Bearings for a 1990 Yamaha YFM250 MOTO-4 ATV.
Disclaimer: This guide is provided for general informational purposes only and is not intended to replace your ATV's official owner's manual. Always refer to your manufacturer's documentation for model-specific instructions, torque specifications, safety procedures, and maintenance requirements. If you are unsure or inexperienced, consider seeking assistance from a qualified mechanic or technician.