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Aprilia RS660 Tech Discussion

Discussion in 'Tech' started by Monsterdood, May 2, 2022.

  1. Busdriver02

    Busdriver02 Well-Known Member

    Interesting. I just tried to measure the Woodcraft clamp on mine (best I can while actually on the bike) and 8-ish is about correct. Clamp thickness, and general imprecision of my hand measuring not withstanding anyways.

    Interesting note: I have the Ohlins rear shock. It's range of length adjustment is 303.5-309.5. With 308 being stock (I think) and 309 being the Ohlins recommended length in their little starting setup pamphlet. Since Ohlins did the development on the Trofeo bike, it makes me wonder if their thought process was the tires will only get larger in diameter from the stock street tire, 180/60, 190/60..

    Good catch. I just looked at the spec sheets for each, the listed unmounted diameter for the front tire is 4mm larger in diameter for the Dunlop, so it would be 2mm closer to the rad. If you're picking nits to only just brush it, I would think that plays a part.
     
    Monsterdood likes this.
  2. cu260r6

    cu260r6 Well-Known Member

    I'm having a similar problem to a massive degree. How did you get the bike to turn tighter on the gas? I have .85 fork springs and a 120N rear and am going to try a 130N to hopefully solve the problem. My shock is still at the stock 308mm with the front raised 10mm to prevent the tire from hitting the radiator. I've raised the swingarm mount, reduced shock rebound, increased shock preload, increased shock compression and still haven't found a cure.
     
    Maxtrap likes this.
  3. Monsterdood

    Monsterdood Well-Known Member

    My guess would be you need to add a few more mm to the rear shock and maybe go a little stiffer on the rear spring to give you more support in the rear and through the corner and on corner exit. If you don’t have enough swing arm angle (shock too short), you might not get enough anti-squat on corner exit thereby squatting the rear and making it run wide. Low speed compression in the rear would help too if you have a shock with low speed adjustment.

    I am going to try the front end 2mm lower to try and get a little better finish to the corners but I’ll watch the front tire rub closely just in case. I’m also running .95’s in the fork and that might be holding the front end up a little higher too, but I really like the front end feel so don’t want to mess with it too much. It’s not bad, but I want to try a little sharper turning feel.

    Also note, I have 1 race weekend on the bike and am no suspension expert. I think I get the basic gist of this stuff, but am not an expert suspension guy.
     
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  4. Busdriver02

    Busdriver02 Well-Known Member

    120 seems extremely light no matter what you weigh. I think the stock spring is something like a 128.
    For reference the Ohlins shock comes with a 160 as the "standard"
     
  5. Monsterdood

    Monsterdood Well-Known Member

    That’s a really good point. I’m on a 150 rear spring (Ktech comes with 140 stock) and even me moving up to a 160 might help my turning a bit. I’ll try lowering the front end a smidge first but may want a 160 spring to try sometime too.

    I know some guys were running 190 rear springs and really liked it. But geometry and preload and all have to match that stiffer spring for you to get the right anti-squat and swingarm angle for good traction.
     
  6. cu260r6

    cu260r6 Well-Known Member

    What do you weigh on a 150? I'm 170lbs and am considering a 130 or 140.
     
  7. Busdriver02

    Busdriver02 Well-Known Member

    I weigh 165, and I'm running a 160.
     
    Monsterdood likes this.
  8. Monsterdood

    Monsterdood Well-Known Member

    I’m 185 and on a 150 spring, hmmmm maybe if I lose 10lb, the bike will finish corners better… and accelerate faster
     
  9. Busdriver02

    Busdriver02 Well-Known Member

    Considering I just got my racing license, and you can apparently make a MA grid, I wouldn't be surprised if you need a 170 on some tracks.

    On that: If my posts read like I actually know what I'm talking about, sorry. Engineering major in college, so the nerdy stuff interests me.
     
  10. swetngblts

    swetngblts Well-Known Member

    We had my forks (.95 ktech) flush with Robem triples. My last race wekend on the Aprilia we bumped up the penske shock (800#) to 310mm from 308. Bike setup was real good. Went the fastest i ever had and consistantly. 310 just felt a touch too high to me. Dropped it back down to 308 and did a laguna trackday. I personally think 308-309 is the target. This aprilia is the best race bike i ever raced. I never had any issues with turning this bike. Zoran dialed in the suspension on point, like he always has.
     
    Monsterdood likes this.
  11. Monsterdood

    Monsterdood Well-Known Member

    So the Robem triples have a 5mm drop and you lengthened the forks too if I recall correctly. We should probably just reference the fully extended length from the axle to the bottom of the triple since that is the real geometry starting point.

    I need to confirm if my Ktech cartridges are also lengthened. Looking at the fork slider, it would appear I am not using the last 20mm of travel. I don’t have a travel indicator on them (yet). But that might mean they are longer too.

    With forks 2mm above Spider clamp, I’m at 483mm from lower triple to axle (pulling down on wheel to get that last 8mm of travel). I raced at VIR with that at 485mm (forks flush).
     
  12. swetngblts

    swetngblts Well-Known Member

    We started at 465. Added 10mm and dropped a couple more mm to make top of forks fully flush with triple. So right around 478-480.
     
  13. Monsterdood

    Monsterdood Well-Known Member

    Thanks! So I was an extra 5-8mm in fork length which would be why it felt a little more sluggish. The first time I rode it, the length was closer to 477 and it was super responsive so I lengthened them and added a little preload. Maybe a bit too far but I agree the bike handles great.
     
  14. TWF2

    TWF2 2 heads are better than 1

    18mm is bottom out.
     
    Monsterdood likes this.
  15. Monsterdood

    Monsterdood Well-Known Member

    Why don’t you stop by the pits at Laguna and tell me what I need to do . Other than opening the throttle that is….
     
  16. TWF2

    TWF2 2 heads are better than 1

    Just look around for one of those kids and let them ride bike. It will not matter what spring is on or at what length. :D
     
  17. Monsterdood

    Monsterdood Well-Known Member

    Kids are dumb. It would be better for you to ride it!
     
  18. Gino230

    Gino230 Well-Known Member

    @Monsterdood Do you run the TC during races? The bikes we ran in Italy had it set on 2, EBC 2. But the dash looks different from ones I've seen here- I'm wondering if they have the same ECU.

    Also, Chandler's crash- he lost the rear. I was thinking TC might have helped save that. He had it off, he says it turns off intermittently. What has your experience been?
     
  19. Monsterdood

    Monsterdood Well-Known Member

    Funny you ask. I have been running with TC at 1 and I have felt it come on a few times here or there and it was very smooth and unobtrusive. I ran it at VIR and Laguna and then in race 1 at Pitt, it flashed a red fault and I lost power on the front straight for maybe 1/2 - 1 second and Alex passed me. It cut out one more time that lap and then no more after that. If it cut out again, I was going to pit, but it was fine the rest of the lap so I stayed out.

    Bobby at HSBK said I just need to run with TC off but then it rained and I figure it would be a little extra insurance. I turned TC to 2 during wet warmup and did not feel it come on at all. I ran TC1 in race 2 and also did not feel it come on at all (which I assume means I need to open the throttle even earlier). But it also did not fault or cutout during the race. Im running the Race ECU customized to HSBK spec whatever that means. It seems like there are different flavors of Race ECUs but I’m not sure what the differences are.
     
  20. Gino230

    Gino230 Well-Known Member

    Interesting.

    The bikes in Italy, we had a couple of those faults, but they did not affect performance. It was loss of some kind of sensor, wheel speed or lean angle or something. The red error message flashes to let you know you don't have TC. But like I said, no effect on performance.

    I don't think it's really necessary on these bikes, but I was thinking it might save a crash like Chandler's- Looked like he lost the rear at max lean angle getting on the gas.
     

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