Tech Tips: Flywheel Removal and Install 2

Need to remove that pesky flywheel out from under the ignition cover to do some general maintenance, or maybe you want to change it for a heavy or lighter version? Either way, we'll show you how to get the job done.

Remember, if you need to get your hands on a new flywheel or other engine components; hit up Chaparral-Racing.com/DirtBikFlywheels

For any other motorcycle parts, accessories, or gear needs, you can find them at Chaparral-Racing.com.

Transcribed version:

"Hey, this is Michael Lindsay from Vital MX. Whether you're just doing some bottom-end maintenance on your bike or you're looking at changing the power characteristic, being able to change your flywheel is definitely a useful skill. So today, we're gonna show you how to open up the side case and change it out. Now that we have our bike here, we're gonna tell you the tools you're gonna need. More than likely, you'll need an 8-mm to get the ignition case bolts off. Once you have the case off, we're gonna get in to the nut that holds the flywheel down. That is typically anywhere from a 14, 15, 17, even upwards of a small 20-mm socket depending upon what bike you're working on. Then you'll need the actual flywheel puller specialty tool, which changes depending upon the brand and model. And then last step, for when we're pulling the flywheel back on, you need a torque wrench to set the proper torque for the nut holding down the flywheel.

So now that we have our bike car side, we just need to remove the bolts holding down the ignition cover. Sometimes, you'll find some of the bolts are multipurpose and hold either some wall mounts here for some wiring. Or sometimes even the cable guide maybe mounted to it as well, so you'll just have to remove that and move that out of your way as you go about it as well. Now, of course, the reason we're doing this...not as common in the fourth show case, but especially for hardcore two-stroke guys, remember? Changing actual flywheel for different flywheel weights can produce quite a bit of different power characteristic, and some people definitely prefer that. Because of the magneto inside, there is a bit, of course, of the magnet going on here. So sometimes, the cases are definitely hard to get up off the dowels. The last thing you wanna do is just take a flat blade and shove it in there. The reason is you don't wanna destroy the gasket surface, nick it, or destroy the gaskets in there. If you look, a lot of the manufacturers cases have little areas on the outside that have room for you to pry on with a flat blade so you do not damage the actual gasket surface. Once you free the dowels, you still wanna be really slow with your disengagement as you come off to make sure the gasket isn't partially stuck to the cover and the case. Otherwise, you might just yank it up and tear it and then you'll end up needing a new gasket.

So typically, flywheel nuts aren't held on by all that much pressure. You can either take a small impact gun to break this loose because, of course, it is on the crank and it will free spin. Or you can get a gear jamming tool, lock the drive gears behind it. Or in the case like I'm doing, you can do this the really old-fashioned way and just find a screw driver, something you can pry off. You wanna be really careful, of course, in the case to not pry off of something you can break. The bright side is these aren't on that tight, so it realistically doesn't take that much to break them loose. But still, be very cautious if you do this without the exact proper tools. And just take it nice and easy. As I said, these actually aren't on all that tight.

Another option for tools is you can always get a wide set of pliers in here that can grab on to the flywheel, really good way to be able to grab it with two tools and break it loose. Okay, now we have our flywheel puller, we have our pin backed out pretty much all the way. Like I said, this area of the threading will actually screw on to the flywheel. So we're gonna grab that down there. This doesn't have to actually be put on all that snug. Just make sure you use up as much of the threads as possible. If you only put it on a little bit and then go to pull it off, it could yank the threads off. So just make sure you're all the way engaged and then start spinning down the center pin. And there you have it. The flywheel is part of where you get your timing marks from. If you look really carefully, you can see them. 

Now, what decides the position when you're putting one of these back on is this groove here, which when you're putting the flywheel on the shaft, there's a little key right here that guides the flywheel to its position. So you wanna line up that groove with the key on the crank. But you wanna be very careful as you're taking it on and off as this key just sits in a groove here and can easily fall out and into the engine as you're working. So you just wanna take your time to make sure you get the flywheel engaged on the shaft and on the key. And as you can see, because the shaft is tapered, when you put it back on by hand, it won't go down all the way. So this comes down to us now putting the nut back on and torquing this nut to the correct manufacture spec, which will pull the flywheel down to the correct position. 

Now that we have our flywheel back on the crank, you're gonna wanna jump in your OEM service or owner's manual to find the torque spec for the flywheel nut. You're gonna set it to that torque spec, that way it sucks down the flywheel to where they want it. Then you're gonna grab your ignition cover and make sure you check the gasket surface. Set the dials to line them up, go in and put that cover back on, tying it down. Then you're good to go to the track. By the way, make sure you check back at vitalmx.com for more tech tips."

Credit: Joe Carlino

C50_profile_1424660203 ML512 9/25/2016 7:40 PM

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