Time for another chain/sprockets

[yarbonwick]

Well I must say that I've been impressed with my drivetrain. After one year and 2months, it's finally time to replace the chain and sprockets. I've been throughly impressed with the stock DID 520VM chain and it's sprockets. I'll be getting another VM chain, however sprockets are another issue. Firstly I can't find them. So, I'm going with either Sidewinder Ti, Sidewinder SS, or some other. But here's my point...

I've been toying with the option of changing the ratio from stock 14/52 to something other. I believe I'll be changing the rear ratio rather than the front so I could revert back and forth as needed without having to break the chain. I want quicker acceleration for those very tight / hilly situations so do I go with 14/54 or 14/50. I always get confused if it's up or down for quicker acceleration.

 

[stretch]

yarbonwick, to increase acceleration you need to increase teeth on the rear sprocket or decrease teeth on the front sprocket. To increase top speed, do the reverse.

Dave

 

[smilinicon]

The stock chain and sprockets are pretty impressive, aren't they? 14/52 will accelerate quicker and have lower top speed than the 14/50. If you want lower gearing (faster acceleration) try 13/50, 13/51 or 13/52. Experiment with your power-valve screw also for power delivery.

--------------------
Cary S.
smilinicon
#197 dist 14,15

 

[Jaybird]

My 125 came stock with a 13/50, which is a 3.85:1 ratio.
I changed the back to a 52, that gave me a 4.0:1 ratio and more low end.
With your 14 tooth front, you would have to go to a 56 tooth rear to gain a 4:1 ratio. I would suggest you change front to a 13, especially if you are going twords the torque end of the scale. With your 14/52 you had a 3.71:1 ratio, you could always get back there (or close) with a 13/48.(3.69:1)
Just divide the rear sprocket by the front to get the ratio, the higher that number the lower you are geared.

 

[dkmccarty5]

chain/sprockets

Yarbonwick - Always divide the #teeth of countershaft sprocket by the #teeth on the rear sprocket. The lower the number - the greater "torque", and hence less top speed. Example: 14/52 = .269 , 14/50 = .280. The 14/52 will provide more low end, the 14/50 will provide more top speed. Word of caution - The smaller the diameter of the coutershaft sprocket, the more rotational stress is placed on the countershaft. Avoid decreasing the countershaft sprocket size, and attempt to make your adjustments on the rear sprocket. Also - larger countershaft sprockets help to increase the life of the sprocket, and hence the chain and rear sprocket. We have just introduced a new 7075 Alum. chain & sprocket kit that includes a Regina Gold "O" Ring chain. click-on the erider logo if interested. dave@erider

 

[TexKDX]

Yarbo -

I run the stock 14/52 setup and am wanting a combo that makes 3rd gear more usable in the tight stuff. I just switched to a shorter rear tire, so I'm withholding judgement until I get to try the new skin. The MT44 Pirelli is a tall tire. I suspect the M12 will change the response in 3rd some.

A 13 is pretty small on the front and will wear quicker than the 14, plus puts more wear on the sliders. At the same time, swapping the rear is a pain in comparison to swapping the front if you ride in different conditions. The 54 may wear the chain guide as well.

Currently I'm leaning towards a Sidewinder stainless rear sprocket in a 52 and a 13 and 14 for the front. When conditions are real tight, the 14 makes 1st gear a little tall and 3rd a little too low in the RPM range. If conditions are more open, then the 14 works great. The 80 MPH top end is overkill for anything I do.

Keep in mind this is on a 300, which has different internal ratios than your bike. YMMV.

 

[Jaybird]

Yarbonwick - Always divide the #teeth of countershaft sprocket by the #teeth on the rear sprocket. The lower the number - the greater "torque", and hence less top speed.

Always??? Is it not easier when dealing with gearing to speak in terms of ratio? Just a thought.

 

[TexKDX]

Jaybird, you and dmmcarty are saying the same thing. Do his math, then put a ":1" after the resultant number and you have a reduction ratio of the final drive.

As Rich has pointed out in previous discussions on this topic, the sprockets only matter when you are talking about bikes that have the identical primary drive ratio in the motor and transmission ratios. The final drive number is irrelevant when you add in these variables. Even if these are all the same, the power characteristics of the different motors will impact final drive gear selection.

To make it REAL simple, work with experiences on the same year/model bike of similar states of tune and modifiucations, then focus on the impact the final drive gearing change makes in specific riding circumstances, riding styles, and conditions. A tooth here and a tooth there, next thing you know it is working as desired. Just a thought from a dummie.

 

[BigStoppy]

Yarb, I like the 54 on my '99 250E since it adds a another link to the over all number of links of the chain (load carried over more links equals less stress per link). I wouldn't run a 13 on the countershaft unless I absolutely had to, since the chain makes a faster turn around the countershaft sprocket (higher pin/link rotation speed = accelerated wear).

I think I read somewhere that Jeremy's mechanic ran a big countershaft sprocket with a huge rear sprocket to (probably a 15/58 maybe) to lessen torque effect on suspension and chain stress problems.

Stoppy

 

[Jaybird]

Tex,
I have the concept, but the "place a 1" thing doesnt work when you divide the driver by the driven, as dkmccarty5 suggested.
Hope this isn't confusing, but what we suggested to do in the way of math are complete opposites. Divide the driven by the driver to get a X:X ratio.
14/52 52(driven) divided by 13(driver) = 3.71which is a 3.71:1 ratio

14/52 14(driver) divided by 52(driven) = .269 using dk's method

All I'm suggesting is that using his method can lead to a bit of confusion because the number doesn't relate to a direct ratio (it does but...), albeit correct math.

 

[TexKDX]

Got it, 'bird. My oversight. Of little value either way other than comparing say 14:52, 13:52, and 14:54 to see how close they are.

 

[yarbonwick]

TexKDX I know what you're talking about on third gear. It's the same for the 00' 250 EXC- a bit tall. That's what I'm trying to take away also for some of the fast tigh trails. When I rode Sam Houston National Park WITH WOODSGUY2000 a couple of months ago, I was bangin' second-third, second-third all day. That's part of what I'm hoping to alleviate, also I generally want more snap. Hmmm, maybe I ought to put a smaller flywheel on, change the transmission out, and remap the ignition. Or Maybe a SX or XC or TM/MX is in the air:cool:

Big Stoppy- Did you have any interference problems with the chain slider?

dkmccarty5 - I'll look into it, thanks.

 

[TexKDX]

Exactly, Lloyd. My 3rd is a tad tall for Sam Houston. I'd like to have it up in the rev range a little more to aid exiting those endless turns. Out at Skull Creek the stock gearing is perfect. After riding the 200E a bit I realize just how tall my 300's 1st gear is too with the stock gearing.

Sidewinder will be alot like Sam Houston. Sand, turns, and whoops. The lower gearing would be of help, but at least a lower 1st won't be required. From what I hear about Trainrobbers this past weekend the lower gearing would have come in handly there too. Too bad they closed all the interstates :( .

 

[KaTMandoo]

Specialty Sprockets...

kinda on topic..........anyone know the website for Specialty Sprockets?


KaTMandoo

 

[yarbonwick]

http://www.sprocketspecialists.com/

 

[KaTMandoo]

hehe..........who'd have thunk it, huh yarbon? lol

thx
KaTMandoo

 

[BigStoppy]

Yarb, you asked,

Big Stoppy- Did you have any interference problems with the chain slider?

I didn't have a problem because I normally run the axle in the rear section of the swingarm which gives a little more space for the larger sprocket, chain guide, and the chain. I dont think I could go to a 56 toother without installing an aftermarket guide, though.

 

[yarbonwick]

Great thanks, that's what I needed to know.

 

[yarbonwick]

Big Stoppy

Man I don't know how you run the axle to the rear. With the 54 I have a problem with too short or too long. If I took only two links out, the axle was very near all the way to the rear, leaving chain stretch adjustment next to nil. Taking another link out, made it short. I had to run the adjusters almost all the way in to make it work and will probably need to purchase an aftermarket chain guide. After riding to check my suspension, I noticed that the guides rubber was rubbing the top portion of the chain. Anybody have any recommendations? Fredette? Moose? Etc.

 

[Jaybird]

Yarbonwick,
Don't you have eccentric chain blocks on that orange beast?

 

[RedRider4]

Jaybird,

Did you lose a lot of top end when you went from 13/50 to 13/52? Or was it not really noticeable? I was thinking about putting a 51 or 52 on the back but was afraid I'd lose a lot of top end! Could you tell a huge difference in bottom end torque? Let me know. Thanks!

 

[yarbonwick]

Originally posted by Jaybird
Yarbonwick,
Don't you have eccentric chain blocks on that orange beast?

How do you mean?

 

[Jaybird]

RedRider4,
I noticed no loss of top at all, of course I ride mainly on groomed track and never use top gear on the track. You won't notice any change in top at all, but I did notice a nice change in bottom. See, I also don't use low gear either. I start in 2nd gear and use it for my low Always. Only time I ever see first gear is if I screw up and go there. 2nd is fine now that I have the 52t rear.
yarbonwick, My sx has eccentric chain blocks on the axle. It allows me to turn the block around and use a shorter adjustment bolt for the same position once the chain is long. In other words, it strengthens the adjustment. Without the block, a long chain would not only have the axle in the rear position, but the adjustment bolts would be taxed out to the end of their travel as well. Not a good thing. The eccentric block cures this situation. I thought ALL KTM's had 'em. (shrug) If you do, in fact, have these blocks on your bike, try experimenting with turning them around.
I thought I would add this for ya yarbon.....I bought a Sidewinder SS chain witht their hardned aluminum rear and chrome-moly front. I've got about 20 hours on em and I have only adjusted the bolt about 1/2 turn TOTAL! I know you are going to hear alot of remarks about the overpriced Sidewinder stuff, but being a man who uses roller chains to make a living, I can tell you that Krause has the right approach to roller chain and sprockets. The keys to happy chains and sprockets are:

• Proper chain tension
• Proper lubrication
• Close tolerances of materials

of course hardned, machined sprockets don't hurt :D

 

[TexKDX]

On the '99 250/300/380 chassis, the chain adjusters only work one direction.

 

[yarbonwick]

Jaybird I didn't realize what you were talking about and took a look. My 2000 does have what you speak. I could turn them around and use them. Wish I would have thought of that before.

RedRider4: Lost lots. But I wasn't worried about that.