The TTR 125 kick start lever is one of the few parts you can break without crashing hard. A slow tip-over in a rocky section does it just fine.
Yamaha built the TTR125 as a kick-start machine from 2000 onward. Even the electric start versions kept the lever as a backup.
This guide covers the four failure patterns and how to separate a lever problem from a gearbox problem.
What Does the TTR125 Kick Start Lever Do?
The lever is a short arm that clamps onto a splined shaft on the right side of your engine. Pushing it down spins the kick gear, which turns the crankshaft.
Yamaha lists it as the kick crank assembly, part 5HP-15620-10-00. One pinch bolt holds it on.
The lever does nothing beyond transferring your weight to that shaft. Every part that multiplies the motion lives inside the case.
Signs Your TTR125 Kick Start Lever Needs Replacing
Bent or Twisted Lever
A bent lever strikes the frame or your boot before the stroke finishes. Lost travel means lost cranking speed.
Check it by eye from behind the bike. The arm should sit parallel to the engine case.
Loose or Wobbling on the Splines
Grab the lever and twist it side to side with the pinch bolt tight. Any rocking means the splines have worn down.
Worn splines deteriorate quickly. Each kick rounds them off a little further.
Lever Slips Without Turning the Engine
This is the symptom riders dread. The lever travels its full stroke with almost no resistance against your foot.
Nine times out of ten the fault sits inside the case rather than on the lever.
Lever Does Not Return to Position
A healthy lever snaps back on its own. A lazy return usually points to the torsion spring, part 90508-26667-00.
Dirt packed around the shaft produces the same symptom. Clean it thoroughly before ordering parts.
Lever Problem or Kick Starter Gear Problem?
Telling these apart takes about two minutes and saves real money.
Run this check:
- Remove the pinch bolt and pull the lever off the shaft
- Inspect the splines on the lever and on the shaft
- Rounded splines on the lever alone means you need a lever
- Crisp splines on both parts means the trouble is internal
If the shaft spins freely by hand with the lever removed, your kick ratchet or kick gear has stopped engaging. That repair means pulling the right-side cover.
What Causes Kick Start Lever Damage?
Tip Overs and Crashes
The lever hangs off the right side with nothing shielding it. Drop the bike on that side, and it bends before anything else.
Tight rocky singletrack in the Pennsylvania state forests claims plenty of them. A walking-pace fall does the job.
Worn Splines
Riding with a slightly loose pinch bolt ruins splines faster than any other cause. The lever shifts a fraction on every kick.
That small movement works like a file. One season takes the fit from tight to sloppy.
Over-Torqued Pinch Bolt
Going too far the other way causes its own trouble. An overtightened bolt distorts the clamp and can crack the collar.
Snug is the target here. The bolt holds alignment while the splines carry the load.
TTR125 Variants: Which Kick Start Lever Fits Yours?
TTR125 vs. TTR125L vs. TTR125LE
Good news on this one. Yamaha used the same kick crank across every variant.
The L stands for larger wheels and a front disc brake. The E means electric start, and those bikes carry the kick lever anyway.
Check Your Model Year Before You Order
The lever holds a single part number from 2000 through recent model years. The internal kick shaft tells a different story.
Bikes through roughly 2007 use shaft 55K-15660-00-00. Models from 2009 onward switched to 5LX-15660-00-00.
That split only matters once your repair goes past the lever. For the lever itself, fitment stays simple.
Stock vs. Folding vs. Heavy Duty Levers: Quick Comparison Table
Three options sit at different price points. Your terrain should decide which one makes sense.
| Type | Best For | Rough Price | Weak Point |
| Stock OEM | Everyday trail riding | $50 to $55 | Bends in hard falls |
| Aftermarket replacement | Budget repairs | $22 to $35 | Spline quality varies |
| Folding or heavy-duty | Rocky technical terrain | $40 to $80 | Hinge needs regular cleaning |
Yamaha TTR125 Kick Start Lever Replacement (Step by Step)
Set aside fifteen minutes. This ranks among the easiest repairs on the bike.
- Put the bike on a stand and let the engine cool fully.
- Loosen the pinch bolt and remove it completely.
- Spread the clamp slightly with a flat screwdriver if the lever sticks.
- Pull the lever straight off without twisting it sideways.
- Clean the shaft splines with a wire brush and inspect them under good light.
- Apply a thin film of anti-seize to the splines.
- Slide the new lever on, positioning it so it clears the footpeg through full travel.
- Fit the pinch bolt and tighten it snug.
- Kick the engine over by hand a few times before you start it.
Tools You Will Need
- 10mm socket or wrench for the pinch bolt
- Flat blade screwdriver to spread the clamp
- Wire brush for cleaning splines
- Anti-seize compound
- Threadlocker for the bolt
Kick Starting Tips That Make Your Lever Last
Technique matters more than most riders expect. Bent levers usually come from bad habits rather than bad luck.
- Push with smooth body weight instead of a sharp stab
- Find top dead center first, then start your stroke
- Keep your boot flat across the lever pad
- Check the pinch bolt every few rides
- Fold the lever in before loading onto a trailer
Summer riding in the Mojave Desert OHV areas creates a specific trap. Hot engines resist cranking, so riders stomp harder. That is exactly when levers bend.
Low-speed crawling through the Texas Hill Country brings the opposite risk. Repeated stalls on limestone ledges mean dozens of restarts in one afternoon.
Frequently Asked Questions
Can I ride with a bent kick-start lever?
You can, although it costs you. A bent lever shortens your stroke and makes hot starts noticeably harder. It also loads the shaft splines sideways, which turns a cheap repair into an expensive one.
How much does a TTR125 kick start lever cost?
OEM levers run roughly $50 to $55. Aftermarket versions start near $22 and climb from there. Add a few dollars for a fresh pinch bolt, which is worth replacing at the same time.
Why does my kick starter spin but not start the bike?
Free spinning with no resistance points inside the engine. Your kick ratchet or kick gear has stopped engaging the crank. Pull the lever off first to rule out worn splines, since both faults feel identical from the saddle.
Will a TTR125 lever fit other Yamaha models?
Treat this as model-specific. Spline count and arm length vary across the Yamaha range. The TT-R110 and TT-R230 use their own kick cranks, so match the part number against your parts diagram first.
How do I stop a kick start lever from loosening?
Clean both sets of splines before assembly and apply threadlocker to the pinch bolt. Tighten to snug rather than maximum force. Recheck the bolt after your first two rides, since the clamp settles once it takes load.
Should I buy OEM or aftermarket?
OEM gives you guaranteed spline fit and consistent steel. Aftermarket saves real money on a part that bends in crashes regardless. For rocky trail riding, two aftermarket levers often beat one OEM lever.
Shop Dirt Bike Cycle Joint Parts for Levers and Controls
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Pull your lever off and look at the splines this week. A worn TTR 125 kick start lever costs very little next to the kick shaft it sits on. Contact us today.
