Chains and Sprockets

So, is that a lock ring washer between the sprocket and the nut with splines cut into it?
Where'd you get it?

OK, as promised, here's the follow-up to the 48t sprocket.

As stated, the starts are better. First is now a starting gear.

I finally got it out with another vehicle to check my suspicions on the speedo:

- 30km/hr shows 38km/hr on the speedo
- 50km/hr shows 60km/hr on the speedo
- 90km/hr shows 106km/hr on the speedo

Now if we extrapolate the data (because, of course, I would not exceed the legal speed limit so this is pure hypothesis and may be full of complete monkey dung) we find that the bike is now capable of 158 on the speedometer which is approximately 140km/hr. That would be (hypothetically of course) be just below the rev limiter. This is compared with my previous record of about 130km/hr on the track (upright, not tucked). Previously the bike could not come close to red-line in 6th gear.

At 90km/hr 5th gear is humming along and you actually have a bit of go. Switching to 6th gear drops the RPMs for cruising at that speed. 6th gear is now useful and 5th gear is more useful than previous also.

I used 112 links with the 13/48. I based that calculation on some things that DerangedHermit had posted over on TT I believe. The axle is now a little bit further back which is also good.
I am currently using an RK Racing 520 X-ring chain. I think RK or DID, or any other brand name is probably fine. I used a rivet link as I despise master-links.

I'm anxious to see how the aluminum sprocket holds up. There is a chance that the sprocket will wear out before the chain. If that is the case I try buying non-sealed chains since they are about half the cost, but don't last.

Overall I am EXTREMELY pleased with the new 13/48 gearing.
It is good for street, track, and highway. Hopefully soon I'll get around to trying it off-road.

Bob wrote:

just to confirm. the front sprocket has a flat side and a spacer side. which side goes towards the bike? i'm gonna look at it here later today and just want another opinion. i'm going to check the stocker to see if it has any built in spacer or not. note i'm not talking about the actual spacer, but the spacer built onto the sprocket.
thanks.

i took off the front sprocket again. it doesn't have a built in spacer. just a cut out on one side. so i left it with the flat side out and the cut out towards the bike. any one else have a sprocket like this? btw, its a supersprox sprocket.

wahilde wrote:

Excellent chart! How can I convert these ratios to top speed on a WR250R with stock motor ( i.e. rev limiter doing it's thing)?

http://www.gearingcommander.com/

I swapped my back gear to 48 on the weekend (allready had a 12 front) and went for a couple hour ride in the tight stuff. Well I was after that. The bike now rides exactly like I want.
I can now pull strongly in 2nd from almost idle and is awesome for the tight and twisties.
I found an aftermarket steel sprocket from the local wreckers that suits a WR250F that has 2 sets of bolts holes, tapered and non-tapered so I didnt have to change bolts.
Now with a 12/48 combo I am pretty limited to around 100kmh but that suits me fine as I ride 99.8% on the trails.

Myself, I'm using 12/45 because I do a lot of off-road riding.
I can still cruise at 55-60mph since the stock 13/43 is geared to the moon, and then some. :)

I ran 12/43 for a little while, which is a touch lower than the 13/45 you're wondering about.
It was much more realistic for the performance of the bike.
Stock seemed so tall, it was rediculous.

ZED wrote:

mwakey wrote:

I just got a 40 rear I am getting ready to try out on my X. I'm keeping the stock 13 front. I commute 99% of the time with this bike and want to see how the 40 effects things. It also would be nice to gain a few MPH for when I want to open it up on the back roads. I'm thinking I can hit a true 100 with the 13/40 combo. I'll post my report after I get it installed.

I suspect with the 40t you're going to be power limited, even with the mods. Please post your thoughts on starts, rideability, and actual top speed when you get to it. It will be interesting to see.

Well, I got a wild hair up my butt and installed the 40 rear (aluminum GYTR) Monday night.



I went out for a ride last night to test it out. First thing I noticed was the take off in 1st was like being in 2nd gear. Riding around the neighborhood in 2nd gear where I used to cruise through in 3rd (to keep the noise down). Once I got out on the highway the first thing I noticed was the extra vibration in the foot pegs. I think this has to do with the GYTR sprocket not having the rubber ring like the stocker. The vibes weren't that bad but I did notice it was more than it was before. I can live with that.

I totally forgot my GPS so I didn't get to see how the speedo compared. But I did like the fact that I could cruise at highway speeds in a slightly lower RPM range. Since I have the tach I was able to see about a 200 RPM drop from my normal revs. Cruising at 60 MPH in 6th gear was about 5900 RPM compared to about 6100 with the stock 42 tooth. I also found that 6th gear was hardly needed for the kind of highway I run on. Speed limits around here range from 45 to 55, (but I usually go a bit faster ). I made it up to the one road I can actually open it up and it seemed like 6th gear was like having a 7th gear. I stopped and did a few quick starts, banging it up through the gears and I was happy with the performance of the 13/40 combo. My butt dyno told me I was getting up to speed a little faster.

Maybe I don't ride like most of you guys, because I am happy shifting at around 7-8000 RPM instead of taking it up to (or near) the limiter when I high speed shift. I did do a few take offs like that though and I got to admit the bike loves to rev up high like that. There is more power there, but I just cringe when I hear it winding up that high. Call me an old man, but I'm happy shifting at a slightly lower RPM. It's still plenty damn quick for my old butt.

Tonight I took another ride and I remembered to bring my GPS to get some speedo numbers, but for some reason the cops were out in force tonight. I couldn't catch a break on any road trying to get a top speed number. I did get it up to 75 indicated once, and the GPS was showing 74, so it's pretty darn close. At other speeds like 45 and 60 the GPS was also within 1 MPH of the speedo. So I'm happy about that. Now I can depend more on my speedo telling me the truth. As for the odometer... I zeroed out my GPS after I fueled up and zeroed out my odo on the bike. After a short ride the speedo said 5.4 miles and the GPS showed 5.8 miles. So the factory odo is reading lower than true mileage. Not sure if that is good or bad. Depends on how you look at it I guess.

I think I need more time on the bike with this new gear combo. Still not sure I like it. It is like riding someone elses bike now. I have to get used to it all over again. I might get a larger rear like a 45 or 46 and try that just to see what it does for me. But I'm thinking I won't like it. I'm not into much off road riding and I'm way too old to be doing wheelies, so the larger rear may not be for me. If I ever get a top speed number I'll post it up for you guys. But I'm guessing I still won't get to 100 MPH with the 13/40 combo. High 90's maybe. But hell, I never get to ride on roads where I can go that fast anyhow.

Now that I have a full tank it's going to be interesting to see what my fuel mileage is now too. I'll keep the GPS on the bike until this tank is gone and compare it to my stock gearing. I think I'll make it a few more miles before the low fuel light comes on now.

i just went with a 12t up front and a 48t in back, i'mreally glad i did this rather than spending alot more money on a new slip on pipe. this really perks up this bike and makes it more rideable. i tried just the front 12 t acouple of weeks ago and didn't like it at all, now with this set up you can use all of the gears, first is not much but now in single track you can use 2nd and third much more effectively.
not doubt best mod for the money, and thanks to yamwow for some advise.
no

OK, I know that proper chain slack adjustment subject has been beat to death on ADVRider regarding stock sprockets on the WR250R, but what is the proper amount of chain slack on a WR250R with a 13/48 tooth combination and how, exactly, do you measure it?

I'm really paranoid of over-tightening and stressing my countershaft. With the long travel of these bikes and the roller above the chain and the fact that I can't really see what's going on back there while riding things could look fine when sitting, but maybe get really stressed when fully compressed and I just want to avoid that. Of course I also want to avoid too much slack and wearing the tops of my teeth off pre-maturely. Any advice is welcome as long as it doesn't involve an unofficial unit of measure such as fingers, knuckles, etc. Thanks folks!

The drive chain won't be at minimum slack at full suspension compression, but at about half way through the stroke when the countershaft, swingarm pivot, and rear wheel axle are all aligned (where you could draw a line through their centers).

I'd just adjust the chain as is shown in the bulletin sent to Yamaha dealers (and is probably all over the Internet) and as a final step, sit on the seat, slide way back to compress the rear suspension, and reach down and tug on the top run of the chain to see if there's a little bit of slack down there.

YZEtc wrote:

The drive chain won't be at minimum slack at full suspension compression, but at about half way through the stroke when the countershaft, swingarm pivot, and rear wheel axle are all aligned (where you could draw a line through their centers).

I'd just adjust the chain as is shown in the bulletin sent to Yamaha dealers (and is probably all over the Internet) and as a final step, sit on the seat, slide way back to compress the rear suspension, and reach down and tug on the top run of the chain to see if there's a little bit of slack down there.

Thanks YZEtc, but there's a problem with using Yamaha's bulletin. It says to measure (with bike on side stand) a given distance between the chain and the swingarm. With a bigger rear sprocket, following that procedure will have the chain so loose you probably wouldn't get out of the driveway.

As for me trying to compress the rear shock so the swingarm is in line with the sprockets and THEN adjusting my chain, well... that sounds tricky. I guess I could use tie-down straps to compress the rear just right and then adjust my chain. I hadn't thought of that. I was just hoping someone had already gone through that stuff and come up with a chain slack measurement with no load on the bike.

It's not that complicated.
Just adjust the slack so the bottom run of the chain has 40-50mm of slack.
Tighten the axle nut and adjuster bolts/nuts.
Hop on the seat and compress the suspension with your body weight.
Reach down and tug on the chain.

If there's a little slack, you're OK.
If it's tight like a bow string, hop off the bike, adjust the slack slightly looser, and repeat.
Once you get it, it won't be a sweat in the future. :)

Been doing a lot of reading lately here and on ADV and ready to bite the bullet on some mods - as right now the bike is completely stock apart from some protection I have added.

First thing I was looking at doing was:
Front Sprocket - new 13
Rear Sprocket - new 48
New tyres - D606

I read today that the higher profile of the D606's is like take a tooth or two off the rear sprocket...

I would really appreciate some input into the choices I have made - pro's and con's and also what you thnk the better brands of chains and sprockets would be - my environment here is dry, salty and rather corrosive to say the least... but full of great tracks :)

I was buying new chain and both sprockets so the wear would be matched across all components and I can keep the stock chain and sprockets for emergencies. I have also read that people were having issues removing the front sprocket - anyone found a good way to get around the issues?

Cheers
Lance

13/46 is what i have for dual sport use. perfect for both worlds. 13/48 is more for trail use. i'm just going to use a 12 when i hit the trails. an impact wrench will take the front sprocket off in 3 seconds or less. i would also buy another locking washer as a spare. i destroyed mine taking it off with out an impact wrench.

Well, my 12 tooth countershaft sprocket arrived today. I had the dealer
order it. Per what was said on here, I ordered a 250F sprocket. His
catalog didn't show a 12T 250F sprocket by JT (which seems to be the
most common one folks on here have used). The next few manufactures,
same deal. Nothing. Then he found one by PBI. Part 757-12 C/S. It
arrived today and I proceeded with the swap tonight.

It was just going too smooth. Easily twisted off the sprocket after
pushing out the two detents a little. Didn't need to pull the rear
axle. Just loosened the chain adjusters all the way and could sneak the
countershaft sprocket off. Put on the PBI and what's this?! It doesn't
fit! The shaft hole is too big. What the heck. Try it and retry it several
times. Refit the original. Fits find. Pull it off and try the PBI
again. Too big. Compare the two side by side and it's obvious the shaft
hole is bigger. So, why is that? I thought any 250F sprocket should
work? I did read one report that one brand didn't fit so they
re-ordered a different brand it it fit. I think the dealers catalog
showed this was for a very wide year range of 250F.

Any ideas? I'll stop in tomorrow to see if they'll do anything. I doubt
it, but if this won't fit this shaft, I wouldn't fit a 250F either, so
then it becomes a matter of not getting the part I need, right?

OK, to confuse matters even worse...Apparently the WR250R and WR250F/YZ250F countershaft sprockets are NOT interchangeable. That, or many sources are plotting to make me go out of my mind. I took the PBI 12T sprocket (Part 757-12 C/S) back to the dealership from where I picked it up last night. One of the mechanics helped me since the parts guy was loading up a sold bike. He looked up the part number and confirmed that this sprocket is for a WR250F. He looked up the PBI 12T sprocket for a WR250R and it was a different part number. He did the same thing for sunstar. Again, different part numbers. He looked up the countershaft for the WR250R and WR250F. Different parts. I said "sure, they are different parts, but everyone is saying the shaft diameter and splines are the same". He says nope. Different diameters. That would explain why the PBI countershaft sprocket's shaft hole was too big to fit my WR250R shaft.

What that doesn't explain is why and how the heck some folks are fitting a WR250R sprocket to their bike. The few people I've talked to recently have run into the same thing. Ordered a WR250F sprocket and it doesn't fit. What the heck is going on here?! Any chance folks actually ordered a WR250R sprocket and just thought they ordered a WR250F and that is why it fit? Or just getting lucky with tightening down the nut so tight, it works well enough? Possible cause of some reports of vibrations? It's all getting a bit hard to figure out.

In any case, the dealer was great and gave me a refund which they did NOT have to do since I told them to order a part that was for a different bike than what I own. Very cool on their part. Last night I ordered the thumpertalk JT 12T for the R. Today they called me and those are on back order until Oct. 12. Once again the forces of evil conspire against me. But wait, there is hope. He looked up a Sunstar 12T for the R and they had one or two left. It's on it's way.

So, I'm not saying definitively either way, but if you are ordering a countershaft sprocket, it might be best to go with a WR250R specific sprocket and stay clear of assuming any old WR250F/YZ250F sprocket will fit our bikes. Would love to have someone with both bikes, or access to both, pull off each bikes sprocket and try it on the other bikes' countershaft. My guess is they will not swap. Still, that doesn't explain how a few folks say they will unless there was some type of mix up or misunderstanding and they are really using a R sprocket. Not impossible because even the dealers mix up the F and R designator since it is opposite on Honda. F is for fun and the R is the for Race where Yammy used F for Four-Stroke Race and now R for our dual sport.

My belief is that the sprocket supplier (PBI, in this case) has their application chart wrong.
I just went through a similar situation with a Vortex brand sprocket and a 2006 KX-450F - the application chart supplied by Vortex listed a part number that would not fit the bike.

The sprocket I have on my WR-250R is a 12-tooth Sunstar.
The Sunstar application chart lists the same part number for the YZ-250F, WR-250F, and WR-250R.
The cardboard packaging for the sprocket even lists these models on it.
Perfect fit. :)

Naturally, the countershaft part numbers for a WR-250R and WR-250F will be different because the engines share little in common.
They just both happen to be called WRs, which is just another marketing angle to sell bikes, not make things easy to understand. :)

JT is is JTF1590-12 and it FITS.

I bought and fit a JT 12T yesterday to my WR.
The reference says 31-5NL-12/09, I have no idea what this means but it fits the bike.
I just went to my local shop and asked for a 12T for a WR250R and that's what they gave me.

antipode wrote:

I bought and fit a JT 12T yesterday to my WR.
The reference says 31-5NL-12/09, I have no idea what this means but it fits the bike.
I just went to my local shop and asked for a 12T for a WR250R and that's what they gave me.

Hmmm, maybe JT is getting in on the name game and came up with a different part number for the R. I just got my sunstar in the mail. Part number 38812. Same part number for the F and the R. The label even says:
Yamaha
YZ 125 05-09
YZ 250F 01-09
WR 250F 01-09
WR250R/X 08-09

My eyeball says this shaft hole is a smaller diameter than the PBI that I returned to the dealer. Won't have time to fit it tonight. Maybe tomorrow night. I'm anxious to regain the snap I lost after installing the D606 a couple weeks ago.

antipode wrote:

Chadx wrote:

I'm anxious to regain the snap I lost after installing the D606 a couple weeks ago.

Chadx I am seriously 'challenged' in the mechanical department.
Can you explain me why changing tires makes you loose anything and in what way? is because the tires have different diameter or what?

Yep, the stock rear trailwing was 120/80-18 and the Dunlop D606, that everyone favors, is 120/90-18. When I compared my odometer to my GPS before and after the swap, the tires seems to change my miles traveled by over 5%. That's quite a gearing change. Equivalent to around 2 teeth on the rear sprocket. Here is a quick chart I threw together to compare gear ratios with various sprockets. One column for a tire the stock height and the second column for the D606 or any other tire that is about 5% taller.

Front	Rear	Ratio with stock tire size	Ratio with D606 (based on 5% change)
14	46	3.286	3.115
13	43	3.308	3.136
14	47	3.357	3.183
13	44	3.385	3.209
14	48	3.429	3.250
13	45	3.462	3.282
13	46	3.538	3.354
12	43	3.583	3.397
13	47	3.615	3.427
12	44	3.667	3.476
13	48	3.692	3.500
12	45	3.750	3.555
13	49	3.769	3.573
12	46	3.833	3.634
12	47	3.917	3.713
12	48	4.000	3.792

antipode wrote:

That's certainly a substantial change! I never though a tire change could affect gearing so dramatically.

Why is people favoring the 120/90?
An Australian magazine called 'Trailzone' has had a project wr250r for about six months and one of their recomendations was to avoid 'over tiring', they recommended going for a 100/100-18. That will sit between the 96 and the 108 of the 120/80 and 120/90 respectively. Do you know what will be the effect of having a narrower tire?

First I should note that my 5% calculation was comparing a worn out trailwing with a brand new D606. A fairer comparison would have been new to new. Some one looked up the manufacturers claimed diameter on both, though, and I think that was around 4.8% difference.

The D606 is being used because it's one of the better dual sport tires. It does not come in a 120/80, hence we are using the 120/90. If it came in 120/80, that is what I would have gone with since it would slightly reduce tire weight. Trailzones recommendation makes sense depending on your terrain of choice. You would have a slightly smaller contact patch and, much like in automobiles, that would afford slightly less traction in many situations. Whether that was a big deal would depend on the rider. I would think it would be most noticeable in loose soil, like sand, or when pushing the bike to it's limit elsewhere. If the tire weight was greatly reduced, that would reduce unsprung weight, which would be good, and also help acceleration a tad since the engine would have less mass to get spinning. The weight difference might be minimal, though, and not have much impact, but it would be interesting to try.

Success at last. Slapped on the Sunstar 12T sprocket (Part number 38812) and it fit like a dream. Only took about 20 minutes (since I had so much practice the first time). Took a quick spin and, due to conditions, couldn't tell much of a difference. I only had time for a quick ride on our gravel road so there wasn't enough traction to hook up and feel a difference. When I get it on the asphalt, I'll report back. I expect to feel a reasonable improvement in acceleration and also expect it to pull both of our overdrive gears (fifth and sixth) better.

When I swapped the trailwings for the D606, my max speed, in sixth gear, dropped about 10mph. Sixth just wouldn't pull like it used to. Even fifth now ran out of steam at 80mph (wind resistance limited and not rev limiter limited). Keep in mind most days my dirtbagz are full and stick out far since they sit over my emerson/rotopax side rack. They really catch the wind. My speedometer will be even further off now, but I'll be able to tell how well I keep up with highway traffic. Also, I have the speedoDRD laying here ready to install to correct the speedo/odo.

The first thing I noticed is more drag on the rear. When the rear wheel was off the ground and I spun it to lube the chain, it didn't spin as easily as in the past. That might be because my chain guide/guard is getting so worn, or that the 12 tooth lets it drag more when it's off the ground. When pushing the bike around the garage, it doesn't feel any different.

Pouring rain and 39 degrees this morning. Driving the cage to work rather than the bike so it will be another day before I do a full test ride.

greer wrote:

BPG,

Holler back and let us know how it works out; I figured I'd go with Rocky Mtn too, when the time comes. Already got the Tusk filters. Thanks.

Sarah

Will do.. Only actually ordered tonight, I was doing some research on a rear tire that I wanted to include in the order (to get some a 'dat free shipping!)

I have to say, Rocky Mountain ATV ROCKS - killer customer service, some of the lowest prices around, plus their website WORKS and is packed w/ useful info (dabble around in Denniskirk.com for 5 minutes and you'll be trying to gouge your eyes out w/ your mouse!).

I ordered their Primary Drive steel sprockets: 47T rear ($20) and 13T front ($9) (I already have a 12T steel front), a nice 8,120 lb tensile strength 520 ORH X-ring chain ($59). Also picked up a spare master link, the tapered bolts for the rear sprocket ($9), a rear Kenda Trak MasterII tire ($50), and a few Tusk-brand oil filters ($4 each).

Free shipping since it was over $100, and I found a few online codes (10% off any order, $20 off orders over $150). REALLY saved a bundle!