Rear Sprocket & Chain

[Silverwolf8264]

Hey all. I am thinking of replacing the rear sprocket on my 09 WR to a 51 or 52 tooth Vortex to increase the torque I'm getting. I know the manual has all the instructions to replace it, but I'm wondering if I need to buy a larger drive chain, since I'm increasing the total "area" the chain needs to travel. I currently have the standard 113 link chain on my bike.

[zuch95701]

One tooth will be fine you wont need a new chain. However if you are going to replace a rear sproket get something that is not going to wear out. The supersprox brand sprokets are a life time warranty. I have had mine for 3 seasons pushing 200 hours on the sproket and chain set everything is still in perfect shape.

[Silverwolf8264]

One tooth will be fine you wont need a new chain. However if you are going to replace a rear sproket get something that is not going to wear out. The supersprox brand sprokets are a life time warranty. I have had mine for 3 seasons pushing 200 hours on the sproket and chain set everything is still in perfect shape.

.... When you said this I expected to check their site and be looking at a $150 sprocket, not a $79 one! (O.o) However, I see the "lifetime warranty" is only if you buy a kit? In any event, do you recommend the black and gold 51 or blue 52 tooth? Will I need a larger chain with a 52?

[ghte]

If you are going up on the rear cog then probably 2 teeth is needed to effect noticable change. On that premise a new chain is probably required. However get the new sprocket mounted and try the existing chain. Push the axel forward as far as possible and make sure you have sufficient chain slack. As an aside if you are riding ST gnarly stuff, shortening your wheel base will improve directional changes and handling with a corresponding offset to straight line stability.

[Silverwolf8264]

Really I'm just looking for more climbing and overall power. I figured a larger rear sprocket would do the trick cheaply.

[ronbuell]

If cheap is what you're looking for, then just swap out the front sprocket for about $17.00 or so. A 12T for a YZ125 will fit. I run a 12X52 on my YZ250F with a WR tranny. You talk about snap, its there!! I've got slow pull for tight or hilly sections, and I've got 4th/5th for fast sections. Only drawback is increased chain wear.

[Silverwolf8264]

If cheap is what you're looking for, then just swap out the front sprocket for about $17.00 or so. A 12T for a YZ125 will fit. I run a 12X52 on my YZ250F with a WR tranny. You talk about snap, its there!! I've got slow pull for tight or hilly sections, and I've got 4th/5th for fast sections. Only drawback is increased chain wear.

Well, I heard (or read) that you should try to keep your front sprocket as large as you can so I didn't really want to mess with it. Also, you're running a 12/52 from 13/50? Man, I think that is a little more than I want but with the WR wide tranny you've really got the best of low end torque and high end speed, don't you?

[zuch95701]

.... When you said this I expected to check their site and be looking at a $150 sprocket, not a $79 one! (O.o) However, I see the "lifetime warranty" is only if you buy a kit? In any event, do you recommend the black and gold 51 or blue 52 tooth? Will I need a larger chain with a 52?

The Super sprox is the three piece black and gold one. Even if you do not buy the kit that sprocket wears great and is well worth the money. Like i said i have a ton of hours on mine with Zero visual wear on the rear sprocket.

[ronbuell]

Wolf, yea, the WR tranny on the YZ engine makes for a lotta snap down low due to light flywheel. I can loft the front wheel in 4th if I need to with a tug, and lower gears at will with a wrist twist. And yes your are correct in that the larger 13T front puts less stress on the chain and it lasts longer. I tried 13X50, 13X51, and 13X52. The smaller rear makes for a greater jump between 2nd and 3rd and I noticed more bogging, which I didn't like. The YZ250F likes to rev. My favorite riding spot has some sections that are fast so I'm in 3rd a lot, 4th some and 2nd some. If my riding buddy is not on it and I cog up from second, sometimes I would overshoot him or bump him if I was behind. At my age, I've got no business going that fast anyway, but even with the lower gearing, I still have 5th for insane speed.

[brewsy]

Don't mean to hijack but I had the same question... I have an 04 yz250f, stock gearing is 13/48 and I was thinking of going with a 49 rear... will the stock 112 chain size fit with the new rear? also DID or renthal chain?

[Silverwolf8264]

Don't mean to hijack but I had the same question... I have an 04 yz250f, stock gearing is 13/48 and I was thinking of going with a 49 rear... will the stock 112 chain size fit with the new rear? also DID or renthal chain?

Stock gearing on the yz is 13/48? .... Interesting. Well, I could not tell you for sure but judging by the responses so far, I'd say the one tooth increase should work with your chain. (Don't quote me though.) As far as brand? No idea.

Wolf, yea, the WR tranny on the YZ engine makes for a lotta snap down low due to light flywheel. I can loft the front wheel in 4th if I need to with a tug, and lower gears at will with a wrist twist. And yes your are correct in that the larger 13T front puts less stress on the chain and it lasts longer. I tried 13X50, 13X51, and 13X52. The smaller rear makes for a greater jump between 2nd and 3rd and I noticed more bogging, which I didn't like. The YZ250F likes to rev. My favorite riding spot has some sections that are fast so I'm in 3rd a lot, 4th some and 2nd some. If my riding buddy is not on it and I cog up from second, sometimes I would overshoot him or bump him if I was behind. At my age, I've got no business going that fast anyway, but even with the lower gearing, I still have 5th for insane speed.

That's sweet. I haven't even attempted to get my front tire off the trail, don't have enough confidence yet to not eat it. Where I ride is mainly in 2nd or 3rd. I'm almost never in 4th or 5th.

[ronbuell]

Understood. When I first got my bike, the throttle cable was tight. I would hit a bump and accidently goose it. Made for some interesting results on first ride, almost ate some tree limbs. So I put a little slack in the throttle and regained control. Then as training, I would speed up and slow down, training myself to slack off the throttle. It was then that I learned to hit some bumps and turn them into launching ramps that would get the front wheel up. Once I did that, I noticed that the rear end smoothed out if I was on the back wheel. After that, I started gradually increasing my speeds and my lap times came way down. My favorite trail times came down from 1 hr 20 to 1 hr, then 50, and fastest of 45 min. I don't run that fast on a regular basis for several reasons, but some sections are faster than others because I can see way up the trail. Anyway, you get the idea, this bike is way faster than I have the ability to go.

[Silverwolf8264]

Finally decided to go with a larger 52 tooth rear sprocket (I'm pretty sure I'm getting a Renthal Twinring since Supersprox doesn't have a 52, or should I just stick with a standard aluminum?). Two additional questions come up with this: First, I assume I need a larger chain for a good fit. Should I buy a brand new one (and what brand) or can I buy some extender links to fit my current chain? Secondly, I've read you need a device called a "speedohealer" when making a sprocket change so your odometer/speedometer will read correctly. Anyone know if this is true?

EDIT: Or should I do a 12/51, as compared to a 13/52?

Edited July 31, 2010 by Silverwolf8264

[YZEtc]

On a 2009 WR-250F, no speedohealer-type unit is needed because the speedometer pickup is driven by the front wheel.

Bikes that get their speedometers driven from a transmission shaft need that if sprockets are changed.

[ronbuell]

You can just run two master links and add a link or two to get the length you need. Then next time you change the set, get the proper length. A good tool to add to your toolbox is a chain breaker tool. They can be used on street bikes and dirt bikes. I've owned one since the 70s.