hey, I am replacing the timing chain on my yz400, i actually have cylinderhead removed(also inspecting) last thing i have to do is remove the flywheel, how do I loosen the nut(can't lock it from rotating)??? am i just stupid what is the trick?

i also just ordered a flywheel puller for my bike yesterday will get it next week.......

You have 3 choices.

1. Use an air ratchet.

2. Place a piece of aluminum plate between the primary and cb gear. (You have to remove the right side cover)

3. Put the bike in gear and place something between the sprocket and swingarm to lock up the back wheel. This is what I usually do.

I can't use option 1 cuz i don't have an air rachet


i can't use option 3 right now cuz the engine is not even in the frame the whole bike is apart.........

so what is the primary and cb gear??


Another option (besides buying the actual holding tool) is to buy a chain wrench. It looks like a vise grip but with a chain hanging off the end. Get it around the flywheel and hold on while you break the nut loose.

Hope this helps.

yes ive seen those chain wrenches...i don't have one, i have those wrenches that have the rubber band(not chain) will that work?? you know the ones you can use for like oil filter removal...

Hey Tammie, the cb is the big gear at the back of the clutch basket and the primary gear is the one on the crank that it meshes with, to the right of the clutch in this pic. You jam a piece of soft metal like aluminum into the gears so the lock up and the crank can't turn.

There is another way if you don't want to pull an engine cover off. If your bottom end and clutch is still together you can put the tranny in top gear and hold the drive sprocket(or get a friend to) with a big pipe wrench. I put a cam chain in mine a couple of weeks ago and that's how I remove mine. You may want to pop on an old sprocket to avoid damaging a good one. Mine wasn't damaged but you could bend a tooth.

You should always install a new head gasket and be careful not do bump the cylinder when the head is off. The head bolts also hold the cylinder down and the right side can lift quite a bit with just the small bolt holding it down on the left side. The stuck base gasket can make it feel solid but you could damage the base gasket with a good bump.

Don't worry about locking the engine at TDC while you're working on it. You don't really need close to TDC until you are installing the cams and only need it exactly at TDC when you are setting the cam timing. You do have to be careful that the cam chain stays tight on the crankshaft sprocket. A loose chain can skip on the sprocket and cause a link to hang at the bottom and the chain will seem too short to fit over the cams again. If you have the flywheel off you can clearly see that it's OK. If not you can measure it. The correct measurement for a properly seated cam chain is 7 ¾ inches measured from the top of the cylinder to the top of the cam chain if you’re holding it up at one point, like by a zip ty. If your measurement is less than that there’s a link hanging under the crank sprocket.

If you can keep the thing from slipping then yeah a rubber band "thing" will work but you'd get a much better bite using a chain wrench. I bought mine for around $20/US. Or you can do what these other guys suggest.

yes ive seen those chain wrenches...i don't have one, i have those wrenches that have the rubber band(not chain) will that work?? you know the ones you can use for like oil filter removal...

I have had no luck with the "rubber band" chain wrenches when trying to remove a flywheel. I tried two different ones.

I then purchased a clutch holding tool from motion pro and have removed several flywheels with it

There are several different ways to hold the flywheel steady while you loosen the nut but I recommend buying the holding tool. It looks like a pair of vice grips with to prongs that fit inside of the holes on the fly wheel. Never wedge anything between gears or jury-rig a job like this 'cause you'll be paying for it in the long run. Go out and get a can of liquid wrench also to help things out. :)

thanx for the advice everyone.........

Never wedge anything between gears or jury-rig a job like this 'cause you'll be paying for it in the long run. :)

The manual actually recommends jamming the gears with a piece of aluminum for some procedures.

Hey one more question, is the nut on the flywheel opposite thread, i mean is it still clockwise to tighten and counterclockwise to loosen??? or is it opposite on the flywheel??

yep,lefty loosey,righty tighty :)

haha i was going to write that..."lefty loosy, righty tighty" but I thought u guys might think I think I was prissy.........haha


thanks for all your advice, i went out and bought one of those rubber strap wrenches and worked first try!! easy and cheap and good to have for other appplications :)

... but I thought u guys might think I think I was prissy.........haha
I just have this sense that calling a girl on a YZ400 "prissy" might not be wise....

hahaha Im anything but prissy thats for sure.....ive got my entire bike in pieces in the basement and doing it all myself.....hence all my questions :)

so here's my latest flywheel i bought the motion pro flywheel puller for yamaha dirtbikes.........normally it would work however I wasn't thinking when i ordering it but i have the Electrex aftermarket stator and flywheel for the YZ cuz i run a headlight and tail light of it ............this flywheel does not have the threads in the center hole like my stock YZ does however have 3 small threaded holes what type of flywheel puller do i need for this...........anyone else have an electrex flywheel on their YZ??

i know there are 3 bolt flywheel pullers, but also is there not some universal type flywheel pullers, i think i saw one that had like 3 arms that kinda holds on to the flywheel while the rod pushes on the center threaded part the flywheel nut is taken off of.......


I use a 3 arm universal puller. The trick is that there’s very little clearance between the flywheel and the case and 2 of the arms have to fit in the tight spot. I kept grinding the arms down and checking them until they just fit. You don’t want to grind too much off and weaken them. Then the hooks at the ends of the arms slip under the flywheel and the center bolt tightens against the end of the crank and the flywheel pops off. You will definitely have to grind down the universal puller, but it only took me 10 minutes on a bench grinder, grind a bit test, grind a bit more…. :)

My experience as a professional mechanic tells me that pulling a device such as a YZF flywheel with a 3 jaw puller is very ill advised. Pulling it this way puts a lot of strain on the face of the flywheel in a way that the engineers did not intend for it to be applied. The center will flex into a dished condition, which reduces the force actually trying to break the taper free, and can permanently distort the flywheel. You can say that you've done it, and it worked for you, but I can tell you that you got lucky. I've replaced a number of them that were pulled, or tried to be pulled that way.

If there are three drilled holes at the center, get a small, universal automotive puller with provision for three bolts to be used. These are relatively easy to find, inexpensive, strong, and usable for lots of different jobs. That's how the flywheel was designed to be pulled, if it's built like that, and it's the only safe way to do it.

Here's a tip. When pulling something like your flywheel that holds on a taper, and you fell like you've run the bolts down as tight as you're comfortable with but it still hasn't let go, rap the end of the pressure screw sharply, not heavily, sharply, with a steel hammer. The shock with work with the puller pressure to snap the taper's "bond" and pop it right off.

i concur with the gray man :)

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