WARNING 12 TOOTH COUNTERSPROKETS

Using a 12 tooth counter sprocket may not be an inexpensive way to gear down your WRR...

Hats off to Mark Sampson at http://www.bigdogadventures.com/WR250R.htm for his heads up on checking your chain guide for wear. Last year I switched to a 12 tooth counter sprocket for about 2500 miles. After seeing Mark's info on his site, checked my guide and swingarm. Guess what??? The chain guide was worn through and grooves 3/32" deep are worn from the chain rubbing on the swing arm's the bottom side. Bike only has 4200 miles total. Hopefully my recent change to the 13/48 setup I now have will solve this problem. H'mmm.... that $12 12 tooth sprocket is costing me $50 for a new guide..... Will be paying closer attention to the chain guide for wear in the future.

bill

Bill,

This was discussed big-time on Advrider and also on Thumpertalk. Turns out it may have more to do with chain tension than sprocket size. Keep an eye on that chain.

Sarah

http://www.thumpertalk.com/forum/showthread.php?t=888166&highlight

http://www.advrider.com/forums/showthread.php?t=329337&page=772 (scroll to #11580)

I don't fall for that claim one bit.
Like Sarah said, it's to do with how the chain is kept and simply normal wear.
My 12-tooth ain't going anywhere. :)

I mentioned this on TT and it is not what most of you want to hear. If you lower your bike with the rear suspension in any way the chain will make harder contact more often no matter what size sprockets you are running. If you are heavier and ride really aggressive with the lowered rear suspension check the slider often.

Not THIS again... yeah, I've got over 8000 miles on my 12T and I have MINIMAL wear on my slider. Bike is fully dropped suspension wise, and really, chain tension should be a no brainer. I check my chain tension and tires before every ride, just a good precaution.

I have also been running a 12t sprocket for a long time. No problems at all. My bike isn't lowered either. Only minimal wear on slider.

Ok, Guess the real question is........ What is the correct chain tension????? Should you go with the manual's speck of bike on side stand, top of chain taught, in the middle of bottom pushing up with 35# of pressure up on chain leaving 1/2" clearance between the chain & swingarm?????? Sarah, how do you measure yours??? I'm all ears since there are occasions I'ld like to drop down to the 12.

bill

HighFive's method is working well for me; this is copied/pasted from Advrider:

"I've developed my own preferred method for setting this chain tension. I make sure I have enough slack to allow 2 1/2 fingers of space between the swingarm and the top half of chain at a point directly inline with the black mud flap. With the bike on a center stand (off the ground), I slide my fingers between the chain & swingarm until I nearly touch the plastic mud flap. This amount of slack has worked perfectly for me, & I don't have to measure with a ruler. Of course, it would depend upon the size of your fingers compared to mine. You might need a little more or a little less. But 2 - 3 fingers seems to work for most riders. Your chain should look a little droopy (saggy) when you put the bike back on the ground."

Here's the link to that page in the thread in case you want to read more of the discussion:

http://www.advrider.com/forums/showthread.php?t=329337&page=395

Sarah

I was thinking to buy 12 tooth counter sprocket but now... i think i buy 48 tooth sprocket. But where i can order this 48 tooth sprocket? And how fast my bike will be go after this mode? If my front sprocket is 12t and back is 48t? And does i have to buy then new chains if i put 48 tooth sprocket to back? And whats chain i buy?

I had 12/48 sprockets on my WR-250R and the bike would hit 80mph on flat ground.
Acelleration was great and the bike was feeling very snappy.
I now use 12/47 and the bike hits 84mph and is nearly as snappy.
I'm using a 110-link chain - stock is 108 links.

Sunstar makes 48-tooth rear sprockets.

awen wrote:

I was thinking to buy 12 tooth counter sprocket but now... i think i buy 48 tooth sprocket. But where i can order this 48 tooth sprocket? And how fast my bike will be go after this mode? If my front sprocket is 12t and back is 48t? And does i have to buy then new chains if i put 48 tooth sprocket to back? And whats chain i buy?

I know it's a lot to read, but it should answer all & more.
https://wr250rforum.forumotion.com/oh-those-sweet-mods-f5/chains-and-sprockets-t5.htm?highlight=sprockets+chains

greer wrote:

HighFive's method is working well for me; this is copied/pasted from Advrider:

"I've developed my own preferred method for setting this chain tension. I make sure I have enough slack to allow 2 1/2 fingers of space between the swingarm and the top half of chain at a point directly inline with the black mud flap. With the bike on a center stand (off the ground), I slide my fingers between the chain & swingarm until I nearly touch the plastic mud flap. This amount of slack has worked perfectly for me, & I don't have to measure with a ruler. Of course, it would depend upon the size of your fingers compared to mine. You might need a little more or a little less. But 2 - 3 fingers seems to work for most riders. Your chain should look a little droopy (saggy) when you put the bike back on the ground."

Here's the link to that page in the thread in case you want to read more of the discussion:

http://www.advrider.com/forums/showthread.php?t=329337&page=395

Sarah

I think I'm going to get real technical about it and go 2.25 fingers.

Sarah

I use 2 fingers, and my chain is snug but not tight on the sidestand. Not troubles in over 8000 miles! I've used this with all my bikes, sportbike included.

Just went to 12/46 from a year of 13/46 and enjoyed the change greatly at the Desert 100 Ironman Poker Run on Saturday. The bike is not lowered in anyway. I guess I'll keep an eye on the guide.

Would it be safe to say,

That the chain is at it's tighets when in the examining position?
Hence when the rear shock is compressed it will get looser?

Six8

no

does this help?

syzygy

sorry the picture did not show the actual swingarm, Just tried to show that there are two arcs of movement with the suspension. When you can draw a straight line through the center of the countershaft sprocket and the swingarm pivot and along the swingarm to the end , the chain is at it's tightest.

Chain tension on this bike confounds me (I'm easily confounded) and it seems bikes may require a different technique depending on whether or not they're lowered.

I tried BluePill's method: http://www.advrider.com/forums/showthread.php?t=538181&page=2
(scroll to #25) and the chain was tight as a banjo string when I set it on the ground. But my bike is lowered and I'm not sure BluePill's is. 2.25 fingers seems more like it for me. I plan to change out the chain/sprockets/chain guide this weekend and keep a close eye on things.

Sarah

edit: Thanks olddog, I'll get my husband and a buddy to help me and we'll see if we can find the tightest point.

I've always checked and set chain tension the way Yamaha recommends in the (updated) manual, i.e. at the mid point of the chain between the rear block and front tensioner, push up on the chain. According to the manual, the chain should have 8-13mm of clearance to the swingarm, or about a half an inch. I usually keep mine between half and three quarters of an inch. Its easy to repeat that because my index finger is about 5/8" across, so I adjust the chain so it can just barely touch my finger if its resting on the swingarm at the midpoint.

Interestingly, ramz came up with ~20mm of clearance (about 3/4") using a much more scientific approach.

http://www.rickramsey.net/WR250Rmaintenance.htm

My current bike is lower 1" with the factory adjustment with a 12T and ~1500 miles. My old bike was at standard ride height, but sat lower for about half its life due to being loaded up for travel, ~17000 miles total so far with this chain tension. Neither bike shows/ed any significant wear on the chain guide. I've had the chain skip on the new bike, but only because I let the tension get really loose.

With my bike lowered as much as it is, my 2 finger rule applied, is about 1 1/2". Tape measure against it showed that.