How to change and adapt gearing on a dual sport (DR650)

Discussion in 'Thumpers' started by FatChance, Apr 13, 2010.

  1. FatChance

    FatChance Road Captain

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    Now that winter is (finally) past, I'm jumping into spring bike maintenance and upgrades, even though it was snowing this morning when I did this. One of the jobs I have been planning on my 2005 DR650 is to upgrade the gearing. These directions will also work for other dual sports with some possible bike-related changes. This may be simple stuff for most, but this should be a tutorial for those who haven't done it before.

    The U.S. DR650 comes with 15/42 (front/rear sprocket sizes) gearing. That gives a 0.357 ratio which is fine for cruising on the highway, but most people want a numerically lower ratio to multiply the torque a little more at the expense of top speed. A dual sport has to work off-road and also get you to and from the trails without riding at red line, so picking the right gearing is a juggling act and a compromise. You can get better gearing with either a smaller front sprocket or a larger rear sprocket (or both). Most people seem to just put on a 14 tooth front sprocket to get 14/42 (0.333) on their DR650, a 6.7% change from stock and are they happy enough with that.

    Where I live in the mountains, I want even lower numerical gearing for crawling up mountain trails and because we are 180 miles from the nearest freeway, maximum speed isn't an issue. Until now, I have been running 14/45 gearing (0.311), or 12.8% lower than stock. The bike crawls and accelerates much better and will still cruise 65-70 on the highway. I wanted three things. 1) to have an even lower gear ratio for offroad, 2) to have more top speed for riding pavement over to Moab or up to Wyoming and 3) be able to switch gear ratios easily from low to high gearing without breaking the chain or removing the rear wheel so I don't have to compromise. But, I don't want to drop to a 13/45 because I think a 14T front is as small as you can go in front and still be good to your chain. Also, I cannot fit 15/45 for the road because the stock 110 link chain is too short for that combination.

    I decided to get a new 48T rear sprocket and use 14/15/16T front sprockets that are clipped in for easy switching. This gives the best of all worlds for me. To fit this, I also ordered a new 120 link O-ring 525 Bikemaster chain from Motorcycle Superstore and the 48T steel rear and a 16T front sprocket from Jesse (look HERE). I already had sitting around an unused 14T and the stock 15T I took off when the bike was new. I also ordered a couple circlips from Jesse as an alternative “quick change” method of holding on the front sprocket so I could easily change from 14/48 to 15/48 to 16/48 wherever I was in about 10 minutes.

    Here are the applicable gear ratios:

    14/42 – 0.333 (most popular)
    15/42 – 0.357 (stock)
    16/42 – 0.381 (for droning on the interstate)

    14/45 – 0.311 (the best all-around, IMHO)
    15/45 – 0.333 (same as the most popular)
    16/45 – 0.355 (about the same as stock)

    14/48 – 0.292 (great for steep mountain trails!)
    15/48 – 0.312 (the same as my old 14/45)
    16/48 – 0.333 (the same as 14/42 that most people run)

    Here is how to do this.

    First, set up your workspace. I'm old and like having a lift so I don't have to bend over.

    [​IMG]

    Take off the front sprocket cover and remove the 3 bolts holding on the sprocket securing plate, remove the securing plate

    [​IMG]

    Then, since I'm replacing my old chain, I ground off the head of one of the chain rivet heads, then pushed it out using a Motion Pro chain tool that pushes out a pin, pushes on a side plate and rivets a rivet master link.

    [​IMG]

    [​IMG]

    Next, remove the chain and take off the front sprocket. Then remove the rear wheel and unbolt the rear sprocket from the rear wheel hub. Here is the old chain and sprockets, and the new chain and sprockets:

    [​IMG]

    [​IMG]

    The front sprocket held on with the circlip:

    [​IMG]

    Next, I have to figure out how long the new chain should be cut down to. It has to fit all three front sprockets and have enough adjustment for both 14/48 and 16/48. It also has to have enough adjustment with 16/48 so that I can set the snail chain adjuster to zero and pull the sprocket off without breaking the chain. To do this, put on the combination that requires the greatest length, 16/48. It is easier to cut the chain shorter than to cut if longer if you make a mistake. Now, put the chain on , clamping one end to the back of the rear sprocket and pull it tight around the sprocket up to the end you have clamped off. Then, if the two links don't match so the new connecting link won't fit (as in the first picture), go to the next link longer and mark it as shown. Be sure the check that you can still slip off the front sprocket with the chain on it to verify the length.

    [​IMG]

    [​IMG]

    Check adjustment for 16/48

    [​IMG]

    Check adjustment for 14/48

    [​IMG]

    Check that the sprocket will come off with this chain length:

    [​IMG]

    Now that you know where the chain should be cut, grind off the rivet head, push out the pin and put it back on the bike.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Now, the chain has to be put back together. I have often run master links with the clip and they are fine. Just clean off the chain plate and put in a little silicone sealer to help hold in the clip (fish swimming in the direction of the chain movement!). But in this case, I am using a rivet master link. So, put on the inner O-rings, lube it up, and push it into the chain on the sprocket. Then put on the outer O-rings, lube, the push on the outer plate as hard as you can with your hand. This chain came with two handy spacers to keep the O-rings from getting squished.

    [​IMG]

    [​IMG]

    Press on the outer plate with the chain tool.

    [​IMG]

    Then, expand the rivets with the rivet tool. The Motion Pro too works great for all these chain jobs.

    [​IMG]

    Raise/lower the bike to get the countershaft, swing arm pivot and rear axle to all line up. This will be the point where the chain will be tightest. Adjust so there is enough slack so the chain isn't tight at this point. Tighten down the axle nut and put in a cotter pin and you're done!

    [​IMG]

    [​IMG]

    [​IMG]

    I now have my DR650 set up at 15/48 (0.312) as this is a great all-around around town gear ratio for me (the same as my old 14/45). If I am going to ride the bike over to Moab or somewhere farther away, I put the bike on the side stand and then take off the front sprocket cover and remove the circlip. Then, loosen the rear axle nut (don't have to remove the axle), push the rear wheel forward to slack the chain, and pull off the sprocket with the chain on it. Put on the 16T front sprocket, attaching the circlip with some pliers, adjust the chain with the snail adjusters and tighten the rear axle nut and I'm ready with 16/48 (0.333 - same as 14/42) gearing. Changing the gearing shouldn't take more than 10 minutes. When I get to my destination, I can replace the 16T with the 14T in 10 minutes and have 14/48 gearing (0.292 - 18.2% lower than stock!) for the trails. Switch back to ride home. Setting up your dual sport like this makes it a breeze to have the gearing you want and to be able to change it quickly and easily.
    #1
    Palnut likes this.
  2. JensEskildsen

    JensEskildsen Long timer

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    I've done, or will be doing, just the same thing with my xt600e.

    Stock is 15/45

    I will mount a 47 for the rear.

    15/47 for everyday rides
    16/47 for interstate and in generel when i'll be riding distances.
    14/47 for the fun stuff.

    I also have some 45 rear sprockes, to gear it even higher, but dont know it im gonna use that. 16/45 is 0.3555 which is high. I feel i have to rev the bike out pretty far between gearchanges.

    The circlip for the CS sprocket lookes wicked, never seen that. That makes it a lot easier. I havent seen that for my bike tho. It would save some tools aswell. How do you mount/unmount that?

    I havent changed gearig during a trip yet, but im gonna ride around 500km in a few weeks, to get to some offroading, so i might will.
    #2
  3. FatChance

    FatChance Road Captain

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    I press it in the groove with pliers and pop it off with a screwdriver. Very simple system that works well.


    BTW, the pictures were shot in a different sequence than presented and I am aware in the final picture that the circlip is not in place, but it was properly installed when I was done...
    #3
  4. fuhgawee

    fuhgawee Thats a road?

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    Well done.

    I've pondered going up a couple teeth on the rear but decided
    to wait and do what you've done. More options and probably a better
    quality chain. Sure hope your chain breaks in sooner than the original.
    Swear my orig. went 4000 miles before it loosened up.
    #4
  5. Northyork

    Northyork Been here awhile

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    Nice detailed description.............Thank you.....:clap
    #5
  6. Rusty Rocket

    Rusty Rocket Life behind "Bars"

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    Excellent write up Slim. It would take 2 days, for me, to type all that.

    I have used the circlip from Jesse for years now without any problems.
    #6
  7. grub

    grub Requires Supervision

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    I am currently running 14/45 and it works great for me but, like you I would still like to easily go a little higher and a little lower. I have been planning this exact change later this summer when I have a little extra coin - how many links did you end up with??

    Pat
    #7
  8. FatChance

    FatChance Road Captain

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    I didn't count, but looking back at the picture of the new 120 link chain just before I cut it down, it looks like I removed 6 links, so I guess I ended up with 114 links.

    [​IMG]
    #8
  9. Hannda

    Hannda Short, fat, bearded, slow

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    :stupid Thanks.
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  10. MRMIGS

    MRMIGS Adventurer

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    FATCHANCE - Nicely done.

    Just a thought regarding your ratio suggestions:

    Any choice of gear ratios that allows a whole number division ( or non prime numbers) between the # of teeth back and front will probably adversely affect the life of the chain. This is because through the power cycle the front sprocket will always be lugging on the same teeth in the rear sprocket.

    Here's an example: Using the 16/48 configuration you mention, tooth #1 on the front sprocket will always be driving teeth #"s 1, 17 and 33 in the rear. Given the smaller # of teeth on the front sprocket the wear and tear on the rear will be magnified if at least one of the two sprockets does not have a "prime number" of teeth. Examples are 13 or 17 up front and 41, 43 and 47 in the back.

    Hope this helps.
    #10
  11. FatChance

    FatChance Road Captain

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    Thank you. I thought I was being smart just getting my fractions right. :lol2

    As always, there is more information available and I'm learning as I go along. Your insight and knowledge are very welcome as this thread is meant to be educational and helpful! I guess the most popular 14/42 (1:3) isn't such a good idea. I was fairly limited by what sprockets were available for the DR650 for what I wanted to do and I also wanted multiple duty, so not everything could be optimal. At least I was able to get a steel rear sprocket instead of aluminum for better wear. I will probably be using the 16/48 (1:3) the least of all and its use will then probably be the gentlest, so hopefully my chain life will not be too bad. Everything is a compromise, in one fashion or another. This will be mine. Thanks! :thumb
    #11
  12. FatChance

    FatChance Road Captain

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    Thanks, Gadget Boy! :wave
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  13. JensEskildsen

    JensEskildsen Long timer

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    Is the circlip a dr650 only fit? Where did you get it?
    #13
  14. WilderRider

    WilderRider Long timer

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    Fantastic write up.:clap

    Thanks so much for sharing and posting the link in the DR650 thread.
    #14
  15. FatChance

    FatChance Road Captain

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    The countershaft on a DR650 is splined for the gear, but has a groove around the circumference of the outer end of the shaft that the stock sprocket securing plate rides in. Normally, you push that plate onto the splined shaft (splines aligned), then rotate it in the groove (splines unaligned) and bolt it to the sprocket. That plate holds the sprocket on the shaft. The circlip is sized to ride in that groove instead of using the securing plate. If your bike has a groove around the circumference of the outer end of the countershaft, you can probably use a circlip, just measure the inner diameter of the groove and go to a hardware store to see what size fits best. The circlips are standard hardware items. I do not know what method your bike uses to attach the sprocket to the countershaft? Does it have a groove around the countershaft? I got the circlip from Keintech HERE. They are very helpful.


    If you look closely, you can see the groove on the end of the splined countershaft:

    [​IMG]

    Here is what it looks like with the circlip riding in that groove:

    [​IMG]

    If your bike has a similar setup, you should be able to do the same thing.
    #15
  16. 243Win

    243Win Been here awhile

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    This is great info, I'm going to give Jesse a call tomorrow and set this up!

    Thanks for a great and very informative write up!
    #16
  17. BlazeMan

    BlazeMan n00b

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    Great writeup and documentation, FatChance. Thanks!
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  18. sasha_j

    sasha_j full time RV'er

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  19. jna

    jna Adventurer

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    Did you have to modify the chain guide to keep the chain from rubbing?
    #19
  20. Adv Grifter

    Adv Grifter on the road o'dreams

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    Love to hear how this works out in the mountains. I was curious where you sourced the 48T rear sprocket, Jesse carries only a 45T. That BIKEMASTTER Chain looks pretty robust, wonder how long it will last?

    Do you anticipate any rubbing issues with either the chain guide or rubber swing arm bumper?

    [​IMG]I use this to cut the chain. No grinding needed, just push out the pins. Also, I thought you would go into Peening technique some, as a lot of guys screw this up doing a Rivet link, either making it too loose (dirt/water enters) or too tight (kink). For me using the RK tool, I had to go slow so as not to ruin an $8 Rivet link.

    Man, with that gearing your DR should climb like a Goat. I've struggled by with stock gearing or a 14T up front. (not good enough) Luckily my bike carburates so well and Throttle response is do good I rarely have to slip the clutch on trails. It pulls OK from the basement. :clap

    Let us know how it rides with the lower gearing. I'm coming up on 25K miles on my DID VM-2 chain, new one in the wings so looking at sprocket options also. Have a great Summer. I've done 4000 miles since December '09, between three bikes.
    #20