If you've spent any time riding pit bikes, you probably know that a crf110 shift shaft replacement is a pretty common rite of passage after a hard fall. It usually happens when the bike tips over just right—or wrong, depending on how you look at it—and that long metal rod gets a nasty bend in it. Suddenly, you're stuck in second gear, or the shifter is dangling at a weird angle, and your weekend of riding is basically over. It's a bummer, but honestly, it's not the end of the world.
The CRF110 is a legendary little bike, but it has one glaring weakness: that shift shaft sticks out quite a bit, and it doesn't take much of a hit to tweak it. Once it's bent, it won't slide through the engine cases properly, and you definitely shouldn't try to just "hammer it back" while it's still in the bike. That's a great way to crack your engine cases, and then you're looking at a much more expensive headache. Doing the replacement yourself might seem intimidating if you've never cracked open an engine case before, but if you take your time, it's a totally manageable Saturday afternoon project.
Why these things bend so easily
The design of the CRF110 is built for fun, but the shift shaft is essentially a long lever. When the bike falls on its left side, the gear shifter takes the brunt of the impact. Because the shaft is made of relatively soft steel (which is actually a good thing, because you'd rather the shaft bend than the engine block shatter), it gives way.
Most people notice the problem immediately. The shifter feels "mushy," or it won't return to the center position after you click a gear. Sometimes it's so bent that it actually jams against the ignition cover. If you're lucky, you can limp it back to the truck, but you'll want to get that crf110 shift shaft replacement done before your next real ride.
Getting your workspace ready
Before you start spinning wrenches, do yourself a favor and clean the bike. There is nothing worse than pulling an engine cover off and having a clump of dried mud fall into your clean oil or onto your clutch plates. Give the whole engine area a good scrub and dry it off.
You don't need a massive professional tool chest for this, but you will need a few specifics. Grab a set of metric T-handles or sockets (8mm, 10mm, and 12mm are the big ones), a drain pan for the oil, and a pair of snap ring pliers. You'll also want a new side cover gasket and, obviously, the new shift shaft itself. I always recommend getting an OEM Honda shaft or a high-quality aftermarket one. This isn't really the place to save five bucks on a mystery part from a random website.
Tearing things down
First things first: drain the oil. If you skip this, you're going to have a massive mess on your floor as soon as you pull the side cover. While the oil is draining, you can start removing the parts that are in your way. You'll need to take off the gear shifter itself (10mm bolt) and the footpeg mount (usually four 12mm bolts underneath). Removing the peg mount makes your life so much easier because it gives you clear access to the bottom of the engine.
Now, here is the part that surprises some people: to do a crf110 shift shaft replacement, you actually have to go into the right side of the engine (the clutch side). Even though the shifter is on the left, the mechanism that actually clicks the gears is behind the clutch.
Remove the bolts holding the right-side engine cover on. Keep track of which bolt goes where! They aren't all the same length, and putting a long bolt into a short hole can cause some real damage. A piece of cardboard with a rough drawing of the engine cover works great—just poke the bolts through the cardboard so you know exactly where they go back.
Getting to the shaft
Once the cover is off, you'll see the clutch assembly. You'll likely need to remove the centrifugal clutch and the primary clutch to get enough clearance to pull the shift shaft out. This is where those snap ring pliers come in handy. Take your time here. If you've never seen the inside of a 110 engine, it might look like a lot of moving parts, but it's actually pretty straightforward.
The shift shaft has a "claw" on the end of it that interacts with the shift drum. You'll see a spring that keeps the shifter centered. Take a mental note (or better yet, a photo with your phone) of how that spring is seated. When you go to pull the old shaft out, you might find that it's stuck. This is because the bend on the left side of the bike is preventing the shaft from sliding through the hole in the engine case.
If it's really badly bent, you might need to use a small hacksaw or a Dremel to cut the bent end off the shaft on the left side of the bike. Just be super careful not to nick the engine case or the oil seal. Once the bent part is gone, the rest of the shaft should slide right out through the right side.
Sliding in the new part
Before you slide the new shaft in, check the oil seal on the left side. If the old shaft was badly bent, it might have chewed up that rubber seal. They're cheap, so if it looks even slightly worn, just pop a new one in.
Lubricate the new shift shaft with a bit of fresh engine oil and slide it in from the right side. You'll have to wiggle the "claw" and the spring into place so they seat correctly on the shift drum. It should feel snappy. Give it a manual test by rotating the shaft to see if it moves the drum and returns to center. It's way easier to fix an alignment issue now than it is after you've bolted the whole engine back together.
Putting it all back together
Once the shaft is in and you're happy with how it clicks, it's time to reverse the process. Put your clutches back on, making sure the washers and snap rings are exactly where they're supposed to be.
Scrape off any old gasket material from the engine case and the side cover. You want these surfaces to be perfectly flat and clean, or you're going to have an oil leak. Put your new gasket on (I usually don't use sealant unless the manual calls for it, a dry gasket usually seals fine on these bikes), and bolt the cover back on. Remember your bolt pattern from earlier! Tighten them in a crisscross pattern so the pressure is even.
Refill the oil, put the footpegs back on, and finally, slide your shifter onto the new shaft. Don't over-tighten the shifter bolt; you just want it snug so it doesn't vibrate off.
How to keep this from happening again
After you've finished your crf110 shift shaft replacement, you're probably thinking, "I never want to do that again." I don't blame you. The best way to prevent a repeat performance is to install a shift shaft brace.
A brace is a simple little piece of aluminum that bolts onto the engine case and provides a second mounting point for the shaft. It basically takes the "leverage" away from the end of the shaft and supports it closer to the shifter. It's probably the best $30 you can spend on a CRF110 if you're planning on doing any serious trail riding or hitting jumps.
Another tip is to make sure your shifter itself isn't too long or made of indestructible steel. Some people think a "heavy duty" shifter is an upgrade, but if the shifter doesn't bend, the shaft will. I'd much rather replace a $20 folding shifter than go through the whole process of opening the engine again.
Wrapping it up
The first time you do this, it might take you a couple of hours, but the next time (hopefully there isn't a next time!), you'll fly through it. There's a certain satisfaction in fixing your own bike and knowing exactly how the internals work. Now that the gears are clicking smoothly again, it's time to get back out there and ride—just maybe try to stay on two wheels this time!