2003 Dyna Low Rider 70t rear pulley to 65t rear pulley

Discussion in 'Harley Davidson Extreme Modification' started by DIEHARD, Feb 27, 2018.

  1. DIEHARD

    DIEHARD Member

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    Hello: Looking to change out my 70 tooth rear pulley to a 65 tooth rear pulley for more top end and less rpm around 60 to 70 mph I heard its been done on some models but not sure if it can be done on mine. My belt is 1-1/8" it has 133 teeth My front has 32 t and my stock rear pulley is 70t. I would like to know if I go to a 65t 1-1/8" rear pulley and use everything else stock will my 133t belt be to long and run out of adjustment .I can get the 65t rear pulley in chrome for 129.00 and have access to a lathe to machine spacer if needed , what I do not want to do is have to replace the belt as this cost as much as the rear pulley and all the labor removing the primary cover , primary chain clutch etc. Has anybody done this on a 2003 low rider.
     
  2. joel

    joel Senior Member

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    I don't know the correct answer but I would think that the diameter of the replacement pulley would be smaller, and you may run out of adjustment.
    Can the pulley supplier be able to answer and maybe supply the properly matched belt?
     
  3. DIEHARD

    DIEHARD Member

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    Thanks Joel yes the rear pulley would be 5 (links) smaller from 70t to 65t and again I want to stay away from changing out my stock belt because of the cost of the belt and all the labor in changing it out. I read about this some where just was not sure if it included my year and model but it lowered rpm at top end like you installed a 6th gear for a very small cost. Years ago approx. 45yrs I replaced a rear sprocket on a YDS250 a Yamaha 250 to a smaller sprocket to try to keep up with my friends Honda Scramblers top end speed. I was hoping someone has done this on my year and model.
     
  4. Jeff Klarich

    Jeff Klarich Experienced Member Contributor

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    Some time back I recall this topic and I believe the guy with the answers would be dolt.
    Hopeful he'll jump in or you can send him a PM.
     
  5. dolt

    dolt Senior Member

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    Just so the OP knows where he is headed with this modification. 25T engine/36T clutch, 32T tranny, 70T rear gives you a 3.15 top gear ratio. Changing to 65T gives you a 2.925 top end ratio which the OP will also feel in the lower gears. A 200rpm drop at +/-70mph would not be worth sacrificing the loss of torque in the lower gears for me but the OP may be OK with it; definitely cheaper than a six speed.:rolleyes:

    70T rear = 69mph @ 3000 rpm
    65T rear = 72mph @ 3000 rpm

    5 fewer teeth @ 14mm per tooth is 70mm, split on the top and bottom run is 35mm, in practice a bit less because of the bend around the pulley. So, if the OP has 35mm (1.375") of adjustment left with the stock belt and pulley to move the wheel back; the stock belt can be used but I am betting there isn't 35mm of adjustment left and new rear belt with fewer teeth will be required.

    The OP could achieve the same results with a 34T trans pulley and 70T rear pulley and retain the OEM belt; adjustment might be tight but many have done it. 2T front = 5T rear.

    Always wise to post up an idea before pulling the trigger; many ways to skin the cat.;)

    EDIT:
    PN 40017-94 = 130T belt
    PN 40012-90 = 128T belt
    PNs may be obsolete, not sure.
     
  6. Jeff Klarich

    Jeff Klarich Experienced Member Contributor

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    Thanks for jumping in Don, I knew I didn't have Alzheimer's.:eek:
     
    Last edited: Feb 28, 2018
  7. tourbox

    tourbox Senior Member Contributor

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    Dolt would be correct on this. Years ago I put a 65T rear on my '96 FLHTCU. Belt ended up way to long. No adjustment left. It also had the 32T & 70T pulleys. I left it stock.
    tourbox
     
  8. DIEHARD

    DIEHARD Member

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    Thanks to everyone with such a quick response , here is what I thinking now. (1st) I need to verify my speedometer with my stock front and rear pulley on. (2nd) Looking at my swingarm slot it seems to me that I can slot this back to allow the axle to slide back more and cut same amount from the rear wheel adjustment block ends and bolting to ensure there is correct adjustment and tension on belt with out the adjustment blocks , bolting or axle bottoming out. These blocks are the key as the fit in the rear opening kind of snug and for the most part keep the axle centered in the rear fork arm. I just bought a set 2 hrs. ago for 11.95 plus 4.00 shipping on e-bay. Looking at your figures that I would be lowering engine 200 rpms overall in each gear and only 3 miles an hour difference on top end does not make me happy, ( are you sure of these numbers) but its a starting place. I will give this a try unless everyone hammers me enough to change my mind also sooner or latter the primary cover is coming off along with the primary chain and clutch assembly , this would be a good time to replace the 32t front pulley and install the 34t front pulley if I fill the need to lower the rpms more. That would be a 34t front and 65t rear with a stock 133 1-1/8" drive belt this should re-center my rear pulley and I could reinstall my original adjustment blocks. I would verify speedometer after pulley change as this effects its readings. Would the 34t + 65T combo be geared low.
     
  9. Jeff Klarich

    Jeff Klarich Experienced Member Contributor

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    There was a thread a while back and the OP was trying to accomplish the same thing you are asking about.
    The general consensus was why go through the time and money to only drop 200 RPM'S.
    Not really worth the effort. JMHO.
     
  10. dolt

    dolt Senior Member

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    Diehard is one of those that learns the hard way.o_O

    Yes, I am sure of those numbers and if you are happy with a 200rpm drop and the 3mph difference on the top end, replace the 34T trans pulley, keep the OEM belt and call it good; cheaper, safer and a lot less headache but IMHO, still not worth the time and effort. Save about $500 and buy an Ultima six speed trannny and swap them out.

    The 34/65 combination is a waste of time. 2.753 final drive, 400rpm drop or running about 10mph faster at 3000 as compared to the 32/70 combination means the bike would be in constant lug mode, about 2600rpms running about 70mph (I consider anything less than 2500rpms lugging). The bike would be total dog and the motor would not be "happy".

    These vtwins were intended to spin, so let'em spin.;)
     
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