Suspension / Chain tension / Sprocket alignment - problem - HELP PLZ

Discussion in 'Some Assembly Required' started by sdbryan, Sep 1, 2018.

  1. sdbryan

    sdbryan Adventurer

    Joined:
    May 24, 2018
    Oddometer:
    19
    Location:
    San Diego, CA
    I am currently working on converting a KLR 650 to a fat tire 2WD bike.
    https://www.youtube.com/channel/UCrEdyFcfeDdmSys7cMCrkiw

    I am totally running in to a problem with the rear suspension. I thought if I kept the gears running from the drive sprocket to the drive sprocket or jackshaft that I would not have a huge problem with the chain getting loose.

    Well, it doesn't seem the rear suspension pivots in a way for the chain to be loose when fully compressed, correctly tight in the middle and then slightly loose when fully extended. The rear suspension is loose when compressed and tight when it is not. So when you sit on the bike, the chain always gets loose. I am running similar sized gears from the drive jackshaft to the jackshaft on the suspension.

    Not sure of the best way to describe this. I will be uploading a video hopefully this weekend showing the problem. Even when I move the jackshafts closer together, there is still some significant loosening of the chain that I am trying to resolve. Dammit!

    https://www.youtube.com/channel/UCrEdyFcfeDdmSys7cMCrkiw
    #1
  2. kalaby

    kalaby Adventurer

    Joined:
    Aug 28, 2018
    Oddometer:
    20
    Location:
    haribolaa
    same problem here too.
    #2
  3. flybynite

    flybynite So far so good

    Joined:
    May 30, 2016
    Oddometer:
    235
    Location:
    Gangsters Paradise, SA
    WHat is the tyre size of the original wheel and what is the tyre size of the fat wheel ?.
    #3
  4. DiggerD

    DiggerD DougFir from SuperDuke Days

    Joined:
    Mar 14, 2013
    Oddometer:
    2,879
    Location:
    Mid Wet Or A Gun
    Disclaimer: I did not spend a lot of time watching the vidos..actually zero time before I wrote the stuff below. Farmers down the road from me with deep pockets have built fat tire bikes from 450 cc bikes, rear wheel drive only. Don't have any photos tho. Have fun on your build.

    Set it up so your chain is always loose or you will destroy the bearings on both ends,
    along with the chain and sprockets.

    Mantra to live by: A loose chain is a happy chain.

    You can take up the "too loose chain" with a spring loaded skate board wheel, or a slider made out of a UHMW type of material.
    Back in the day when long suspension dirt bikes were entering the sport, after market manufacturing houses made and sold these units.
    I had one on my 430 husky.
    They might still be available.
    This idea is not motorcycle dependent and there are other devices to keep chains from flopping around and coming off track.
    I'll see if I can find some on the web....

    https://www.ebay.com/bhp/motorcycle-chain-tensioner

    https://www.mcmaster.com/#chain-tensioners/=1efu12c
    #4
    lnewqban likes this.
  5. Luke

    Luke GPoET&P

    Joined:
    Aug 25, 2004
    Oddometer:
    4,829
    Location:
    Beaverton, OR
    A drawing would explain things well. Since you're talking about multiple jackshafts it's not clear what's going where.
    #5
    dirt hokie and DiggerD like this.