just to clear things up, a 15T sprocket DOES fit with no clearance issues. it is really close to the cases saver, but it is ok. I had to take off the chain slider and bench grind about 3mm off the end for clearance, but no issues there.

i read on here that they fit but mine didnt

how did it not fit?

mine fit in, but it rubs at some point. It wore a groove in the guard

I think thats what i had to grind down so it didnt wear a groove.. not like it matters anyways. are you talking about the rubber guard chain slider, the aluminum case saver, or the plastic sprocket cover guard?

the case saver was in the way

mine fit just fine.

yeah, i didnt have to do anything with the case saver.. it WAS really close though... was yours aftermarket?

i ahve an aluminum case saver that i think is like a modquad or hellbound racing. i oreder one today but will it clear everything else? chain sliders and what not? i really dont want to grind that stuff!

the stock stuff works with a 15T sprocket. like i said, i took off the front lower chain slider and took off not much at all on the bench ginder. its not even noticeable and im sure you will be fine without even grinding anything.

Did all you guys have to remove the stock lock washer deal, since it doesn't line up with the grooves now? I bought a primary drive 15t i believe and it sits out on the splines further so, the washer is pointless now.

Any comments??

uhh, i guess you dont NEED the washer, but i would highly suggest it.. did you put the nut on to see if the sprocket seated more back on the splines, then take the nut back off and put the washer on.. my washer fit on fine, the stock and the JT racing sprockets are the exact same width

Yea no luck, it is just shaped a little different, filled in/wider in the middle so it takes up more room on the spline.

thats sketchy. i would definitely loctite the crap out of it.

or just go fast... as the splines turn, the nut tightens, lol

Thanks..lol.. I did loctite it with blue, debating going red instead.

if your talking about the washer that you lock down agaisnt the sprocket nut... so the sprocket nut doesnt come loose... you def wanna have that lock washer on and if it doesnt fit then somethin is not right with the installation. just imagine if that sprocket flew off at high rpm's, im pretty sure its gunna tear your leg up. ive got a 15 tooth on mine and everything fits like stock except the cover. i wouldnt even ride mine if i didnt have that lock washer on the sprocket nut. just my .02

REAL TAWKKKK... DOnt w00ter with that it will run your leg like a w00terin chainsaw...

i would definitely go red and maybe even look into getting a diff sprocket. that washer is definitely there for a reason.

Something is wrong with the installation or that is a poorly cast sprocket. I run primary drives front and rear, 13 through 15 on the front depending on what terrain and/or sand conditions I'm riding, and they all work with the lock washer. So, go get a new sprocket, new lock washer, and try again.

So how much actual space is on the splines of the shaft for the washer to fit?? I took the primary drive sprocket off and put the stock back on and there is just enough space for the washer to go on. With the primary drive sprocket it ends up flush with the end of the shaft so there is no room for the washer to fit on the splines. I will take some pics so you can see. Can anyone give me a measurement on how much shaft is sticking out of the case?? I did just rebuild my motor, but don't really think anything can be wrong. It runs fine and shifts fine. I never pulled the gears out when I rebuilt it, just installed a new crank and bearings.

stock sprocket + washer comes out to flush on the splines... at least for mine.

Ok well here is some pics, if someone can give me some feedback. The stock sprocket and washer is pretty much flush. The Primary drive with no washer is pretty much flush. No one else has this problem?? I can put the washer on if I want, but just pointless if it doesn't go on the splines of the shaft. Ok so I just measured the width of the grooves and the stock sprocket is 5mm thick + 1mm washer, not quite flush with the end of the splines by about 1mm short. The Primary Drive is 8mm thick and flush with the end of the splines.

Stock no washer


Primary drive no washer


Comparison

Are you sure that is the right sprocket for your quad. My 15 tooth fits with the washer, and is the same thickness at the splines as the stocker? I would double check. Have any machinist buddies? They can thin it for you on a mill. Or just spend $20 bucks on one that fits.

Also, is there any spline left on the back side, closest to the motor? If so... Sometimes the tolerances are real tight, you might try tapping it with a large socket and a mallet. Just tap it, don't whale on it!

Ok well I measured the splines from the piece in the seal and the cover which are flush, to the end of the splines and it is 8mm. So it sounds like the sprocket is just to big.

Can anyone confirm with my measurements, that they have the same thing, as far as splines showing with no sprocket, or what they have for a width of a Primary Drive Sprocket???

I don't have any machinist friends. I could do it myself, if I had a mill, or access to one. I will return it to RM, if I can confirm some things, as I already discussed it with them. Also I shouldn't have to machine it.

No difference between the years and sprockets. I can tell by your pictures that your motor and stock sprocket are fine... perfect. You have a bad 15 tooth sprocket. Mine all fit just fine on my 06 and on my 04 motors.

15 tooth needs a little grinding on the stock case saver to fit. 15 tooth with most of the aftermarket case savers do not fit and need lots of grinding to make them fit.

damn that 15 tooth looks almost twice as thick as the stocker. i would send it back to RMATV and get the correct one, tell them they better pay 4 the shipping too.

Thanks for the help. I did have to grind the heck out of the case saver though lol..

Yea it is quite a bit bigger, 3mm to be exact lol.. I will call them tomorrow. They should cover shipping as it is a defect and I haven't ran it. I have never had any issues with them returning products. Not trying to get into a debate about RM just saying.

Sorry Joester for hijacking your thread....

Thanks to everyone for their help!!!!

Ok well come to find out, I was using the wrong sprocket. I ordered a 15T for both my kfx450 and the yfz. Well I went on checked the part numbers to make sure I used the right one, well somehow between the house and the garage I mixed up which was which. After speaking with RM today we got it figured out and the measurement is right now, or close. The sprocket is about 5.5mm, which should be plenty enough room.

i think that you were thinking that the stocker was the 15T. the stock one is on the right and looks realy hink, but it gets smaller in the middle. the 15t os on the right.

and no problem for jacking my thread, but thats embarassing.

and no problem for jacking my thread, but thats embarassing.
[/quote]

nah, just a simple mistake. The only difference in the sprockets is 2.5mm. At least I noticed something was wrong from the start. First time ever changing the sprocket. I was just sure I had the right one and didn't want to try the other one thinking it was for the kfx.

yfz and kfx use the same sproket i thought? i got a renthal that says its for yfz and kfx works just fine.

Yes they will fit, but I would be a little worried about how straight the chain is running since I found there is a almost 3mm difference in thickness between the 2. So if you can assure the chain is running straight, I wouldn't see a problem, other than the one I ran into with the lock washer not fitting on the yfz with a kfx sprocket.

Maybe other brand sprockets are the same thickness, this is just what I found with the Primary Drive sprockets.

my 15t fit but the case saver wont fit on. I can grind it to fit and what about a cover? I wear over the boot pants and so far ive been lucky with not gettting it tangled up, any company make ones to fit a 15t

my stock case saver and cover fit with no grinding...

My stock case saver fit with no grinding, however, I ended up buying a Bling Star Billet case saver and it needed a decent amount of grinding to get it to fit. A dremel worked great to grind it down.

Kind of off topic, but how much bottom end do you lose when you go to the 15t sprocket. I'm thinking about trying it and was wondering what everyone thinks.

it was a quite noticable loss, but i ride alot of sand and it still spins the tires. if you ride grippy dirt or MX then i would stick to the 14T

i always change back to a 14T for the track.

so say im at the dunes and im running a hill in 3rd pinned pretty much red lined.. if i dropped to a 13t front would i be hitting it in 4th and gaining the hill or would a 15t do that

a 13 would cause this if you have a 14 stock now

i have a 14 tooth front sprocket on my yfzr and if i go to a 15 tooth will that be to much for mx??

yes, unless your motor is extremely built... i always go back to 14T for the track.

then would it be best to just go down one in the rear??

i would keep it stock, unless you need the extra speed. but yes it would probably be a little better that way

ive heard that every one tooth change in the front is about the same as 3 tooth change in the rear.

i would really advise keeping it stock for the track, the effects on low end torque is very noticeable and you probably dont need that much speed on the track, just torque.

yes i just put mine on last night. it affected bottom end but i still like it! it will be great for riding in the pasture and more open riding that i am doing. i will rpobably put my 14 back on for the trails though, so i dont burn my ckutch up in the slow stuff. and btw my nut wasnt that tight at all. it still had the factory washer holding it, but not that tight. i also had to grind down my case saver quiete a bit!!! i wasnt to thrilled about, but the chain coller, slider was fine.


grs22 if you went from 20inch factory to 18 rears, putting on a 15 would bring it back to about stock gearing. sorry i didnt think of that.

Dude you got the wrong Primary Drive sprocket I am looking at my Primary Drive 15t I just got from RM and it does not have that extra lip on it like yours is showing. My looks just like the stock one you have pictured only bigger.

if you would have read the whole post you would see that he made a mistake and put his kfx450 sproket on.