Aprilia RS660 Tech Discussion

The rotor button trick came straight from Robem. Stock rotors on stock wheels and dymags. No problems.

 

Both of my bikes are Robem builds and one was raced by them- so I'm surprised that they didn't bend the rotor buttons to begin with. I looked at the spacer issue, the Dymags only use a spacer on one side, and they're captive. It would be impossible to assemble it with the spacers in backwards.

I was wondering if some people left the pinch bolt loose and just wired the axle or something crazy.

The funny thing is when the bike is hot, it rolls very freely. It's only when cold on the stand that the wheel only spins half a turn. Which makes sense because when you're riding, the rotor is keeping the pads at bay.

One bike has some kind of Vesrah pad Robem uses and the other is SBS Dual Sinter- I'm getting rid of both because I like a pad that lets me squeeze the lever harder. I've never cleaned the rotors or anything, so that's a possibility- but the fact that it's happening on both bikes is what leads me to believe it's not that.

I should point out that this only happens when braking HARD from top speed- end of the back straight at COTA and Daytona turn 1. If I apply even more pressure it reduces the vibration, so there's a small window where it's happening. The rotor buttons would make sense.

The second bike I got from them this weekend is a chassis they raced in 2023 with a dumbed down engine build for me. I was amazed at how much better it handles than mine- they measure out exactly the same. But that's another story.

 

2nd bike?

 

The second bike I got from them this weekend is a chassis they raced in 2023 with a dumbed down engine build for me.[/QUOTE]

What do you mean dumbed down engine? I thought that was a Superbike engine.

 

It is a superbike. Rods, ported head, cams. I just meant it's not the full on build they use in MA- so it will last longer.
Last year I rode the R6 at probably 15 track days and races- and then when I got on the ape I was never comfortable- so alot of my work didn't translate into going fast when it counted. So this year I sold the R6 and I only have the 2 Aprilias now.

I was never comfortable on mine, for whatever reason I couldn't get the bike to do what I wanted and was not comfortable enough to start forcing it. Once I got on Rocco's old bike, I knew I was right all along and something is not right with my original bike.

 

I'd love to hear what felt different about them. Static measurements are one thing, but there could certainly be a difference in fork/shock setup or tuning, assembly etc.

Regarding the brakes, I've had this problem on bikes in the past with stock rotors. I've gotten brembo full foating buttons before and replaced all the stock ones and the problem has been eliminated with the additional freeplay of floating buttons. First check the obvious things like correct disc/wheel/fork position and assembly with the front axle.

 

When I got my bike it was delivered sprung .90 front and 150 rear. I couldn't get it to turn in and once I did make changes to get it to turn in, it won't finish the corner. We started going progressively heavier on the rear spring, (using some experieince with one other MA rider who is my size) but that took several rounds as getting big springs is not easy for the bitubo (You have to order in advance from the motherland.) Part of the problem is I didn't ride the bike much or at all between MA rounds, so when I got to the track there was no setup time. Or I would ride it a few sessions at Homestead and it would do ok, but when we got to someplace more flowing I would struggle. I tried alot of different spring combinations, and we have AIM suspension data, but that is new to us and using it to set up the bike can be a learning curve compared to the old school methods.

The best the bike has ever been was at COTA and I was down to .85 on the front and 170 in the rear with more ride height in the rear than basically anoyone uses. I'm 200lb and running a 1.0 in my R6 so .85 was never comfortable for me- no braking stability and the damping (clickers) had to be almost closed (or in the case of the shock completely closed) to make it work. But the data showed the bike was finally in the geometry range it needed to be, so we went with it, and it was pretty good.

Then the Rocco bike gets delivered to Daytona with .90 front and 150 rear and I'm like "this is never going to work" but I just rode it and.....it was really good. The rear is a little soft, I can feel it squatting a bit on exit, but it holds the line, and turns great, and feels better on the brakes. It also feels much more balanced when I bounce on it in the pits. I was immediately 2 sec faster and that's riding them back to back during the Team Challenge. I did 10 laps on the rocco bike and I got back on mine and felt like I was going over the bars just leaving pit lane. So we took out some ride height and preload but then it went back to not finishing. It also has the feeling that is hard to describe, but it doesn't want to turn in and when you put more force into it, you start getting the tuck under / spring back feeling, and that to me means there's too much spring in the rear and the rear is pushing the front.

So the next thing to try is the suspension valving. It is surprising that it could be that sensitive to valving, but there's no linkage so the shock movement is critical for chassis geometry.

We have weighed them, measured them, checked the triple clamp inserts, the swingarm pivots, measured the bar and seat heights, checked triple clamp torques, and anything else I could think of. I know I am always on here talking setup, but once I get comfortable I barely turn a clicker for entire seasons. Just got to get a baseline!

 

Interesting. Was your original bike a new build or used donor bike? I’ll be curious to see what you find with it. Has the geometry been measured other than what we did at NJ ?

 

I shit you not, there is/was a Ducati Tech bulletin with very very similar complaints.
The remedy was spray WD40 on each button and whack them with a dead blow small sized.
Clean wheel after.

Problem solved. Apparently brake dust can get in there and build up.

 

Well I did bend up all the little button tabs, and cleaned the rotors with scotchbrite and brake cleaner. Hopefully that solves the problem.

And I only stabbed myself with the screwdriver once. Not a bad day in the garage.

 

This kind of thing fascinates me. I am very interested in learning what you find.

 

My guess is it's the valving in the shock. The Bitubo has high and low speed compression and the bike started acting way better when we threw a Hail Mary and closed the high and low speed clickers completely. My thought is that it's getting more support in the rear this way. I think the Rocco bike is better because the shock has been revalved. Matt has told me that he sometimes uses thicker viscosity oil in the shocks as well. We have less damping in the rear on my bike, and thus we've been trying to compensate by adding more rear spring and ride height, and softer in the front. So the balance of the bike is off.

When I got the Rocco bike, the high speed comp was almost completely closed and the low speed comp was wide open. So it's probably got a compression stack that offers more support.

Also, you have to be careful mimicking the kid's setups too much. The put a lot more force into the bike, especially with trail braking, and they are significantly smaller so what works for them may or may not work for me.

It's ironic because when I rode the bike in Italy I basically did nothing- I was comfortable right away and I just pushed. I think we added a few mm of rear preload halfway though the weekend and that was it.

I feel the same way about the Rocco chassis right now- nothing holding me back but me. The other bike is a different story. We'll soon find out, we have lots of track days coming up while the rest of the world is snowed in.

 

Well, good news, we got a sponsor to step up and we have just ordered 2 new Aprilia Engines, and JM frames. I am still trying to sort out what I need to make this a reality and the electronics are going to be the hardest part I believe.

OBV in Dirt Track, we dont need or want ABS/plus all the others BS for street use. I am still waiting on final rules regarding TC and wheel speed.

Im wondering, since we are running 19 inche wheels, can I just custom mount the rings and use them or is it like a DUcati where it throws everything crazy if you even use a different size tire?

Basically I need the thing to run, make power, and not have 42 lights on the dash. Actually, on that note, do I HAVE to run a dash? I know a majority of guys are thinking WTF, but there are NO Aprilias in AFT so we will be the test mules.

 

Would you have to stick with the OEM harness and ecu? I'd think for your use it might be far easier to go with a motec or other standalone and have the freedom of adjustment.

No, the bike doesn't run without the dash. I'd probably hide it in the frame or somewhere its not going to get hurt though as they're not cheap to replace or easy to find in a pinch.

 

yea I’m thinking the stock harness will be a bitch to cut up, so prob best to go complete standalone. I have a email to AIM. The appear to offer a nice harness setup.

im hoping to not have to use a dash of if I go standalone or at least a basic smaller unit. Won’t be a lot of storage on this thing.

I have a lot of fab work ahead but really excited

 

Keep us posted when you have time. Sounds like a fun project

 

Will prob do a build thread on them. Pretty exciting times with some really cool plans for 2025. Will update when engines arrive!