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Thread: CRF450R - SM Chain offset ( rub ) fix

  1. #1

    Default CRF450R - SM Chain offset ( rub ) fix

    So I now have the 5" * 17" wheel with 160 Pirelli SC tyre installed and
    clearing the chain and swing arm. There are a few steps to achieving
    this as follows;

    STEP1
    Use a spacer or 2mm flat washers between the sprocket and the hub.
    Ensure that you loctite and securely tighten all sprocket bolts. On my
    bike I could have gone another 2mm but 2mm was enough. See picture 4

    STEP 2
    Remove the front sprocket. Use a 1mm or 2mm spacer inside the sprocket
    and also install the sprocket in the reverse direction. The nose side towards
    the engine. This will move the sprocket out between 3mm and 4mm. Again
    use loctite on the bolt and secure using the original washers. See picture 1

    STEP 3
    Undo the two screws securing the top of the chain guide on top of the
    swing arm. The point closest to the front sprocket is mounted over a raised
    section. You need to cut the rubber chain guide such that the guide can
    be moved to the outer side of the sprocket by about 5mm. See picture 3

    STEP 4
    The upper chain guide is L shaped to help keep it in position. As we want
    to move it out we need to take some material from the L part and about
    3-4mm will do it. I used an angle grinder on the rubber and it worked well.
    See picture 2

    STPE 5
    Sit the upper chain guide where you want it. You will have cut the
    top off the part that sites over the raiser screw mount, so now the chain
    guide should sit each side of that raised section. Install the screw and
    washer to clamp in position. See picture.

    STEP 6
    You will have to drill a new hole for the end mount of the upper chain
    guide. About 6mm-7mm from the original hole. You can use a 4mm drill
    bit and a steel self tapper to hold it in place. See picture 4 & 6

    STEP 7

    The lower chain guide needs to be modified. The 160 tyre will not fit in.
    The lower chain guide has two pieces coming down from the swing arm.
    I cut off the inner section. Then bent the assembly out, about 8mm.
    The chain support will still mount to the outer support and is still strongly
    held in place. Will post a picture later.


    So now you chain should be sitting about 5mm from the tyre and running
    true ( Pic 5 & 7 ). I gleamed much of this information from www.supermotojunkie.com
    an excellent site for motards. The information came from many posts and
    also my input.

    Use this technique at your own risk! Only posted for track bikes.
    Attached Thumbnails Attached Thumbnails ChainOffset1.JPG   ChainOffset2.jpg   ChainOffset3.jpg   ChainOffset4.jpg   ChainOffset5.JPG   ChainOffset6.JPG   ChainOffset7.jpg   ChainOffset8.jpg  

    Apexmoto Inc - Dyno tuning, engine/chassis/suspension upgrades, repairs, shaken, tires & changing with balancing, graphics printing, stickers, media blasting, painting & powder coating.

  2. #2
    Join Date
    Nov 2008
    Location
    Vaginia Beach, VA
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    3,632

    Default

    Hmmm track bikes only huh???

    I see this happening to the 250 soon so I can get that 150mm rear...

    PS Did you offset the spokes at all like I suggested the other night??? Just wondering how that worked out for you???

    Phil
    Quote Originally Posted by Loco
    If you find a message from myself offensive, inappropriate or disruptive, please ignore it. If you don't know how to ignore a posting, complain to me and I will demonstrate.

  3. #3

    Default

    No I did not offset the spokes. I could, and shift the wheel off center, but there is no
    need with the above mods. Now I have about 5mm clearance on both sides. If I offset

    via the spokes I would have little room on the non chain side. Thanks for the input
    though.


    A side point, apparently some of the hub makers ( Talon and one other ) offer a
    version for the CRF with the sprocket mounts thicker than normal, so the sprocket
    sits closer to the swing arm to give more chain clearance, similar to my mod.

    Track only? For summer at least. I can put it back to off-road mode in about 2hrs.
    Nothing I have done is irreversible. As mentioned I want to do quite a few track
    days this year, and with that, some touring and camping with my family, the year
    will be pretty full.

    Apexmoto Inc - Dyno tuning, engine/chassis/suspension upgrades, repairs, shaken, tires & changing with balancing, graphics printing, stickers, media blasting, painting & powder coating.

  4. #4

    Default

    Don't know how or where but this washer ( inside the main sprocket bolt disappeared ) causing the sprocket to come off. Fortunately that was before entering
    the track..............


    Apexmoto Inc - Dyno tuning, engine/chassis/suspension upgrades, repairs, shaken, tires & changing with balancing, graphics printing, stickers, media blasting, painting & powder coating.

  5. #5

    Default

    A bit more detail on the mod to the chain guard. Basically the inside
    part of the chain guard has to be cut off. Also unbolt the chain guard and
    then the remaining support is flush with the swingarm. When the wheel is
    installed, reinstall the bolt in lower part of the chain guard.

    SD

    asked

    the
    Summing up, I can unbolt the chain guard when removing the wheel. And
    reinstall after reinstalling the wheel. Not so difficult.
    Apexmoto Inc - Dyno tuning, engine/chassis/suspension upgrades, repairs, shaken, tires & changing with balancing, graphics printing, stickers, media blasting, painting & powder coating.

  6. #6
    Join Date
    May 2004
    Location
    Clayton, California, USA
    Posts
    2,344

    Default

    Cool thanks for the photos! Tweaking these bikes to overcome hurdles is half the fun, lol.

  7. #7
    Join Date
    May 2004
    Location
    Clayton, California, USA
    Posts
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    Default

    Thanks again Jav, I'm getting there.

    I will need a shorter chain, the stock sprocket is a 48 but I have a 44 on the Excel supermoto wheel and the chain has way too much slack even with the adjusters all the way out. Plus I will need to trim the plastic protectors over the fork lowers, the guard is so wide that it rubs the front tire.

    It sure is fun to hang your bike from the garage rafters.
    Attached Thumbnails Attached Thumbnails crf-wheels.jpg  

  8. #8

    Default

    Ah yes, I did have to trim the front fork plastics. But was easy. Used a hot knife and
    then filed the plastic to make it look smooth.
    Apexmoto Inc - Dyno tuning, engine/chassis/suspension upgrades, repairs, shaken, tires & changing with balancing, graphics printing, stickers, media blasting, painting & powder coating.

  9. #9
    Join Date
    Oct 2007
    Location
    Hachioji
    Posts
    2,093

    Default

    Many thanks Jav for posting this. Made my mods so much easier.

    However, thinking about when I go to sell the bike, I was debating what would be easiest/cheapest to bring it back to 100% stock?

    I decided I could cut off the inner part of the lower chain guide bracket and then I would be able to space it out ~2mm. Even aftermarket lower chain guides can be had for almost next to nothing, and I felt if I screw this up, it would be easier to try it again than having to fix the swingarm.







    So far so good. Looking forward to trying it at speed!

    Dana
    A man will marry a woman hoping she never changes but a woman will marry a man hoping he will change. Author Unknown

    2010 Yamaha WR250X
    2008 CBR1000RR Race Bike (For Sale)
    2004 Multistrada 1000DS (For Sale)

  10. #10

    Default

    Looks very neat Dana and way too clean.......................

    Good job.
    Apexmoto Inc - Dyno tuning, engine/chassis/suspension upgrades, repairs, shaken, tires & changing with balancing, graphics printing, stickers, media blasting, painting & powder coating.

  11. #11
    Join Date
    Oct 2007
    Location
    Hachioji
    Posts
    2,093

    Default

    I should add that it's a pain to get the rear wheel on with the rear brake caliper assembly and not trimming the chain guide bracket (that extends from the swingarm). Phil suggested I sit indian style with my legs crossed under the rear wheel and manuever it that way after I've dropped in the wheel from the top.

    In order NOT to scratch the heck up out of my rim, I layered some tape on the edges of the lower chain guide arm that sticks down from the swingarm, allowing me a little more agility to move it side to side and back and forth.

    Considering I don't plan on taking the rear wheel off that often, I thought I could live with fighting it every now and then.

    Dana
    A man will marry a woman hoping she never changes but a woman will marry a man hoping he will change. Author Unknown

    2010 Yamaha WR250X
    2008 CBR1000RR Race Bike (For Sale)
    2004 Multistrada 1000DS (For Sale)

  12. #12
    Join Date
    Nov 2008
    Location
    Vaginia Beach, VA
    Posts
    3,632

    Default

    Call a Wambulance for Dana he is drowning in his own tears!

    Quit being a baby and cut the swinger! Hahahha
    Quote Originally Posted by Loco
    If you find a message from myself offensive, inappropriate or disruptive, please ignore it. If you don't know how to ignore a posting, complain to me and I will demonstrate.

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