Lightweight Flywheel

Discussion in 'TR650' started by SixDaze, Jul 31, 2014.

  1. SixDaze Husqvarna

    Location:
    Michigan
    Husqvarna Motorcycle:
    TR650
    I just got done installing my latest mod to my TR. I bought an extra flywheel from eBay and put it on a diet. The stock unit is around 7.3 pounds and I managed to get about 1.7 pounds off of it. Here are the pics. I'll post more details if people are interested.

    HuskyFlywheel 011.JPG HuskyFlywheel 012.JPG
    HuskyFlywheel 014.JPG
  2. V8Astro Husqvarna
    AA Class

    Location:
    Central US / Missouri
    Husqvarna Motorcycle:
    2014 Strada / 2008 SMR510
    Other Motorcycles:
    Suzuki GS500, Yamaha TR125L
    How did it respond? I would think that with the tall gearing and the light flywheel it would make it more difficult to get going from a stop.
  3. SixDaze Husqvarna

    Location:
    Michigan
    Husqvarna Motorcycle:
    TR650
    So I have about 75miles on the bike with the new flywheel. I can't say that there is a downside yet, but it is early. The bike starts fine, pulls away from a light just fine, and it wants to rev a bit faster due to the loss of inertia. So far so good. Now that I have done it, I can see that there is more to be had here. I pulled 1.7lbs out of the assembly, but I can probably get that down even more if I wanted. The next step would be much more involved, so I'm not sure I'm doing it yet.

    But for those of you considering this mod, it isn't as spooky as you might think. Getting the bike apart is dead easy if you have the flywheel puller tool. The lathe work is $50-60 bucks if you have to purchase that service, and the re-assembly is 30min tops. I did this before on my Ducati and it was VERY responsive to the change. The Husky change wasn't as dramatic, but well worth the time.

    Feels like a fat kit that just took his asthma medicine.....
  4. mag00 Husqvarna
    Pro Class

    Location:
    Tucson
    Husqvarna Motorcycle:
    Terra, Strada
    Other Motorcycles:
    XR250 R1100RS CH50
    How is the balance now?
  5. SixDaze Husqvarna

    Location:
    Michigan
    Husqvarna Motorcycle:
    TR650
    No change at all. The balance is managed on the magnet, not on the flywheel. Reducing the diameter of the flywheel has no effect on balance here, provided it is done on a lathe. The drill holes for balance were not modified. Engine is as smooth as it was before.
  6. V8Astro Husqvarna
    AA Class

    Location:
    Central US / Missouri
    Husqvarna Motorcycle:
    2014 Strada / 2008 SMR510
    Other Motorcycles:
    Suzuki GS500, Yamaha TR125L
    Very nice. Cool mod!
  7. Thumpa Husqvarna
    AA Class

    Location:
    san francisco bay area, california usa
    Husqvarna Motorcycle:
    TR 650 Terra
    Other Motorcycles:
    CCM Dakar, G650X
    SixDaze, nice job! Couple of questions. Did you do the lathe work yourself? Second question, does this mean the original flywheel is for sale?
  8. Greg Jetnikoff Husqvarna
    AA Class

    Location:
    Bundaberg Australia
    Husqvarna Motorcycle:
    TR650 Strada
    Other Motorcycles:
    BMW F80R
    If I was racing it this would be a must do, but not convinced it is all that useful for road riding. If you do lots of twisties then yeah. Really only helps accelleration of the motor under free running ( ie when blipping the throttle) which helps gear changes but a big single like this has huge punch anyway. Not a silly mod but would need to ride it to be convinced it was worth it. The extra rotating mass also helps with avoiding wheel hop on change down but the Husky uses BMW's ecu/throttle trick to smooth that anyway so not an issue here anyway. I assume the Ducati had a slipper clutch otherwise flywheel reduction could be a receipe for throwing the bike down the road on an overshift down ( was PART of the MotoGp Ducati's problem for a few years, insufficient flywheel weight).
    Let us know if it really improves things in the twisties and I might do the same.
  9. Greg Jetnikoff Husqvarna
    AA Class

    Location:
    Bundaberg Australia
    Husqvarna Motorcycle:
    TR650 Strada
    Other Motorcycles:
    BMW F80R
    Actually I just thought of something else. The reduction in flywheel rotating mass MAY help with the turn in ( gyro effect) because it is a fair bit if reduction. Now I really am keen to see if it helped. A lighter 17" front wheel would help more though.