640 Counter Sprocket Question

Discussion in 'Thumpers' started by sherpa, Feb 5, 2006.

  1. sherpa

    sherpa ...Robert

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    I replaced my 16T with a 15T sprocket today, and being a noob with all things about chains/sprockets...I ran into a few questions. It's an 05 640, I'm the original owner, and I've got 1600 miles on it...

    1) Why was there no locktite on the counter sprocket nut and why did it just spin off with hand pressure:bluduh....good thing the flanged washer was bent over the nut :eek1 ...

    2)The original 16T sprocket had a rubber flange on each side...the 15T sprocket did not. Uhmmmm...looked in my 05 parts book....no rubber flanges...got on the computer and pulled up the 03 parts book...no rubber flanges there either. Okay...the rubber flange must separate and I'll just switch it over to the 15T, because it had the same holes for the rubber as the 16T. That didn't work....the rubber flanges aren't designed to separate....they tear instead. So I just put the 15T sprocket on without the rubber flanges.

    What is the function of the rubber pieces, obviously they are not the norm?

    3) Does the particular sprocket setup affect chain tension. The diagram in my 05 manual shows the three ratios 15:45 16:42 17:42.

    I've got a 15:42 on there now to give it a try...does that change the amount of sag/freeplay I want in the chain...:scratch....I wouldn't thing so, but the manual listing those ratio's got me wondering....

    [​IMG]
    [​IMG]
    #1
  2. creeper

    creeper Still alive...

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    The rubber flanges are original equipment only. To my knowledge, they are there to aid in passing noise regulations for a new bike and serve no other purpose.

    Don't know why the nut wasn't loc-tited... maybe because it has a locking tab.
    KTM started using the nut in either '04 or '05 on 640As. '03 and earlier use a bolt like the 660 Rallye, and they come with a dry loc-tite patch applied.
    They've used both methods for years on various models... why I don't know.

    This is my arrangement... running a 15:40 set.

    [​IMG]

    Question number three. Gearing (within limits) does not effect the method of establishing chain tension or the specification. If you had something way different... then the point of reference for chain tension would no longer be accurate, but the total movement of the chain would remain the same.

    C
    #2
  3. ChrisC

    ChrisC Amal sex?

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    Hey Creepy....

    What style o-ring does your fancy gold sided Regina use? I'm about due for a drive train update...
    :cry
    #3
  4. rjf

    rjf SBS's #1 fan in January

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    Hey Serpa,

    My stock '03 had the rubber damper thing. I replaced it with chain gang.com.au sprocket's with no rubber stuff. I read a post a while back where they thought the rubber was for noise reduction. I guess its either that or to try and debris from getting down to the shafts seals, mabye.

    Re chain tension you will have to adjust it, if thats what you mean, but it shouldn't be too far out with only 1 tooth difference.

    If you cannot get it tight / loose enough using the adjuster bolts, you can rotate the adjuster blocks around 180 deg. to try and get it back in range, as the parts that touches the adjuster bolt head are different lengths on either side of the axle.

    I just re read your post "does that change the amount of sag/freeplay I want in the chain". My appoligies if you allready knew the above. I don't think it would.

    #4
  5. rjf

    rjf SBS's #1 fan in January

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    Creep and CrisC - fook you guys can type quick.
    #5
  6. ChrisC

    ChrisC Amal sex?

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    [​IMG]
    #6
  7. sherpa

    sherpa ...Robert

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    Noise reduction...:dunno...that would of never crossed my mind....thanks for the replies....

    One more question...Looking in The World Famous Index Thread under the gearing thread, there is mention of a downloadable spreadsheet for calculating various sprocket combinations...the download link is not working...is that spreadsheet still available? :ear

    Here's the spreadsheet... http://www.advrider.com/forums/showpost.php?p=1478046&postcount=50
    #7
  8. markjenn

    markjenn Long timer

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    I think we concluded a while back that KTM is not shipping any replacement sprockets with the rubber dampers. They're not necessary.

    Whether your bike uses a nut or bolt to secure the CS sprocket (they changed it at one point), I'd use loctite. The loosening of this fastener is a problem area. If you have the earlier bolt-style, you need to be cautious of torque - we've had a few bolts break off and there are two different strength bolts (12 and 8) spec'd with a different torque for each. Personally, I think using the stronger bolt and the lesser torque (loctited ) is probably the safest bet. Drilling the cover and using locating marks to keep an eye out for loosening is a great idea that I haven't done (yet).

    15, 16 or 17 in front can generally be compensated for by the chain adjusters in the rear without changing chain length. But, of course, you do need to adjust the chain when you change sprockets to return to the appropriate free-play. Which BTW, is also a tricky issue - it is very easy to adjust the chain too tight. The spec is to put the bike on centerstand and have the chain just be barely able to touch the swingarm on the bottom run aft of the plastic swingarm pivot guard. It's not a bad idea to strap the bike down and make sure this adjustment isn't too tight. I was surprised that this spec, which seemed loose on the centerstand, was slightly too tight with the suspension compressed worst case (where the axle, swingarm, and countershaft axis are all in a straight line).

    Cheers,

    - Mark
    #8
  9. creeper

    creeper Still alive...

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    Regina ZR brother CC.
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  10. The Misinformant

    The Misinformant What road?

    Joined:
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    I have a 15 16 and 17T front depending on what I am doing (still running a 42 rear). About to fit a 44 rear as I find the 17/42 just a bit to tall with a load on, big winds, cruising at 110kph.

    Hopefully the 17/44 will put me a little taller (somewhere between stock 16T and the 17T). It will make the 16/44 just a bit shorter than stock and the 15/44 will be good for silliness and some of the really snotty rocky hill climbs here.

    I like the design of the chain adjuster blocks as when I run the 17T front and set the chain tension (the blocks on the short side) and if I change to the 15T front only need to flip to the long side and not need to play with the adjusters. It is a big difference in gearing though. Works good to go somewhere - quickly change then a quick change to come home.

    By the way "go some where" often means 500-900km each way.

    :deal
    #10
  11. braaap!

    braaap! waiting for the big one

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    So Mate, you musta' been on the test team for the 03 (uber?) seat design





    No wonder rjf needs medication!


    :D
    #11
  12. sherpa

    sherpa ...Robert

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    I didn't have to switch the blocks around, on my 05, going from the 16 to the 15...and I'm guessing, but it doesn't look like I'll have to switch them to bump up to try the 17, plenty of threads on the adjuster bolts...the blocks are short side forward...maybe there have been some changes to the business end of the swingarm...:dunno
    #12
  13. meat popsicle

    meat popsicle Ignostic

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    Hey you use the same grease as me :D

    The spreadsheet is available in my Yahoo Briefcase under "External Links to Other Downloads" (sic). Lots of stuff in there; help yourself and enjoy.

    ps - "changes to the business end of the swingarm" would be unlikely under my guesstimation if it means redesigning a swingarm or retooling a production run. Unless it means big improvements. What will be interesting to see, not that you will remember this by the time you get there, is if you can adjust your chain thru it's entire lifespan (stretch) on both sprockets. In case you can't the reverseable spacers might come in handy at some point.

    pps - Speaking of doing the creepy mod and drilling the CS cover, I wish we had an inside guy who could make the rallye CS cover available. I'm not dredging up a pic (they are everywhere) but their CS cover just covers the top and a bit of the front so you can see pretty much the whole she-bang (WTF is that word anyways :dunno). I looks like a plastic part like ours. Perhaps I will cut mine off to match.
    #13
  14. bikepikespeak.com

    bikepikespeak.com Been here awhile

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    I'm trying to set my bike up to switch between 16 and 17 CS sprockets. I'm starting out with the 16 up front and it won't take much adjusting to change to 17. My question though is: Is there anyway to change these w/o breaking the chain? From what I can figure there is not. Correct? If that is true and you need to break the chain how many times is it safe to break it at the master link and re-mushroom it again?
    #14
  15. clintnz

    clintnz Trans-Global Chook Chaser

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    If you let off the adjusters, maybe run the chain off the back sprocket, wiggle stuff around a bit, you should be able to swap front sprockets without removing the chain. It might be a bit tighter with a 17T, but I swap from 16 - 14 now & then no probs.

    Cheers
    Clint
    #15
  16. sjeproductions

    sjeproductions Been here awhile

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    Sherpa, did you have any play in your counter shaft? When cleaning mine the other day, I noticed if I tugged on the counter shaft, it moved in and out just a bit. Felt normal, but I figured I'd ask. Good to know about the rubber pieces, I wondered that myself.
    #16
  17. bikepikespeak.com

    bikepikespeak.com Been here awhile

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    Thanks for the tip. I did try it before I put everything back together and I was able to get the 16 off. When I got the bike all put back together I kicked myself cause I didn't actually try to put the 17 on. hahaa. That 17 fits REALLY snug in there. Not sure if I'll ever even use it. We'll see.
    #17
  18. GodSilla

    GodSilla I did that.

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    A little lateral end play is normal. Just a little..........
    #18